Merge branch 'master' into feature/distribution-options-hooks

53 files changed, 1242 insertions, 1353 deletions

diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index d6768cb8..40db5b03 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 41.4.0
+current_version = 41.6.0
 commit = True
 tag = True
 
diff --git a/.travis.yml b/.travis.yml
index 8b7cece8..7088d166 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,8 +16,9 @@ jobs:
   - python: 3.5
   - &default_py
     python: 3.6
+  - python: 3.7
   - &latest_py3
-    python: 3.7
+    python: 3.8
   - <<: *latest_py3
     env: LANG=C
   - python: 3.8-dev
diff --git a/CHANGES.rst b/CHANGES.rst
index ecde25a5..ba7b4647 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,29 @@
+v41.6.0
+-------
+
+* #479: Replace usage of deprecated ``imp`` module with local re-implementation in ``setuptools._imp``.
+
+
+v41.5.1
+-------
+
+* #1891: Fix code for detecting Visual Studio's version on Windows under Python 2.
+
+
+v41.5.0
+-------
+
+* #1811: Improve Visual C++ 14.X support, mainly for Visual Studio 2017 and 2019.
+* #1814: Fix ``pkg_resources.Requirement`` hash/equality implementation: take PEP 508 direct URL into account.
+* #1824: Fix tests when running under ``python3.10``.
+* #1878: Formally deprecated the ``test`` command, with the recommendation that users migrate to ``tox``.
+* #1860: Update documentation to mention the egg format is not supported by pip and dependency links support was dropped starting with pip 19.0.
+* #1862: Drop ez_setup documentation: deprecated for some time (last updated in 2016), and still relying on easy_install (deprecated too).
+* #1868: Drop most documentation references to (deprecated) EasyInstall.
+* #1884: Added a trove classifier to document support for Python 3.8.
+* #1886: Added Python 3.8 release to the Travis test matrix.
+
+
 v41.4.0
 -------
 
diff --git a/changelog.d/1861.change.rst b/changelog.d/1861.change.rst
new file mode 100644
index 00000000..5a4e0a56
--- /dev/null
+++ b/changelog.d/1861.change.rst
@@ -0,0 +1 @@
+Fix empty namespace package installation from wheel.
diff --git a/changelog.d/1898.breaking.rst b/changelog.d/1898.breaking.rst
new file mode 100644
index 00000000..844a8a42
--- /dev/null
+++ b/changelog.d/1898.breaking.rst
@@ -0,0 +1 @@
+Removed the "upload" and "register" commands in favor of `twine <https://pypi.org/p/twine>`_.
diff --git a/conftest.py b/conftest.py
index 0d7b274c..1746bfb5 100644
--- a/conftest.py
+++ b/conftest.py
@@ -19,6 +19,7 @@ collect_ignore = [
 
 if sys.version_info < (3,):
     collect_ignore.append('setuptools/lib2to3_ex.py')
+    collect_ignore.append('setuptools/_imp.py')
 
 
 if sys.version_info < (3, 6):
diff --git a/docs/development.txt b/docs/development.txt
index 455f038a..28e653fe 100644
--- a/docs/development.txt
+++ b/docs/development.txt
@@ -7,7 +7,7 @@ Authority (PyPA) and led by Jason R. Coombs.
 
 This document describes the process by which Setuptools is developed.
 This document assumes the reader has some passing familiarity with
-*using* setuptools, the ``pkg_resources`` module, and EasyInstall.  It
+*using* setuptools, the ``pkg_resources`` module, and pip.  It
 does not attempt to explain basic concepts like inter-project
 dependencies, nor does it contain detailed lexical syntax for most
 file formats.  Neither does it explain concepts like "namespace
diff --git a/docs/easy_install.txt b/docs/easy_install.txt
index aa11f890..544b9efd 100644
--- a/docs/easy_install.txt
+++ b/docs/easy_install.txt
@@ -317,8 +317,8 @@ Note that instead of changing your ``PATH`` to include the Python scripts
 directory, you can also retarget the installation location for scripts so they
 go on a directory that's already on the ``PATH``.  For more information see
 `Command-Line Options`_ and `Configuration Files`_.  During installation,
-pass command line options (such as ``--script-dir``) to
-``ez_setup.py`` to control where ``easy_install.exe`` will be installed.
+pass command line options (such as ``--script-dir``) to control where
+scripts will be installed.
 
 
 Windows Executable Launcher
diff --git a/docs/ez_setup.txt b/docs/ez_setup.txt
deleted file mode 100644
index 0126fee3..00000000
--- a/docs/ez_setup.txt
+++ /dev/null
@@ -1,195 +0,0 @@
-:orphan:
-
-``ez_setup`` distribution guide 
-===============================
-
-Using ``setuptools``...  Without bundling it!
----------------------------------------------
-
-.. warning:: **ez_setup** is deprecated in favor of PIP with **PEP-518** support.
-
-.. _ez_setup.py: https://bootstrap.pypa.io/ez_setup.py
-
-.. _EasyInstall Installation Instructions: easy_install.html
-
-.. _Custom Installation Locations: easy_install.html
-
-Your users might not have ``setuptools`` installed on their machines, or even
-if they do, it might not be the right version.  Fixing this is easy; just
-download `ez_setup.py`_, and put it in the same directory as your ``setup.py``
-script.  (Be sure to add it to your revision control system, too.)  Then add
-these two lines to the very top of your setup script, before the script imports
-anything from setuptools:
-
-.. code-block:: python
-
-    import ez_setup
-    ez_setup.use_setuptools()
-
-That's it.  The ``ez_setup`` module will automatically download a matching
-version of ``setuptools`` from PyPI, if it isn't present on the target system.
-Whenever you install an updated version of setuptools, you should also update
-your projects' ``ez_setup.py`` files, so that a matching version gets installed
-on the target machine(s).
-
-(By the way, if you need to distribute a specific version of ``setuptools``,
-you can specify the exact version and base download URL as parameters to the
-``use_setuptools()`` function.  See the function's docstring for details.)
-
-
-What Your Users Should Know
----------------------------
-
-In general, a setuptools-based project looks just like any distutils-based
-project -- as long as your users have an internet connection and are installing
-to ``site-packages``, that is.  But for some users, these conditions don't
-apply, and they may become frustrated if this is their first encounter with
-a setuptools-based project.  To keep these users happy, you should review the
-following topics in your project's installation instructions, if they are
-relevant to your project and your target audience isn't already familiar with
-setuptools and ``easy_install``.
-
-Network Access
-    If your project is using ``ez_setup``, you should inform users of the
-    need to either have network access, or to preinstall the correct version of
-    setuptools using the `EasyInstall installation instructions`_.  Those
-    instructions also have tips for dealing with firewalls as well as how to
-    manually download and install setuptools.
-
-Custom Installation Locations
-    You should inform your users that if they are installing your project to
-    somewhere other than the main ``site-packages`` directory, they should
-    first install setuptools using the instructions for `Custom Installation
-    Locations`_, before installing your project.
-
-Your Project's Dependencies
-    If your project depends on other projects that may need to be downloaded
-    from PyPI or elsewhere, you should list them in your installation
-    instructions, or tell users how to find out what they are.  While most
-    users will not need this information, any users who don't have unrestricted
-    internet access may have to find, download, and install the other projects
-    manually.  (Note, however, that they must still install those projects
-    using ``easy_install``, or your project will not know they are installed,
-    and your setup script will try to download them again.)
-
-    If you want to be especially friendly to users with limited network access,
-    you may wish to build eggs for your project and its dependencies, making
-    them all available for download from your site, or at least create a page
-    with links to all of the needed eggs.  In this way, users with limited
-    network access can manually download all the eggs to a single directory,
-    then use the ``-f`` option of ``easy_install`` to specify the directory
-    to find eggs in.  Users who have full network access can just use ``-f``
-    with the URL of your download page, and ``easy_install`` will find all the
-    needed eggs using your links directly.  This is also useful when your
-    target audience isn't able to compile packages (e.g. most Windows users)
-    and your package or some of its dependencies include C code.
-
-Revision Control System Users and Co-Developers
-    Users and co-developers who are tracking your in-development code using
-    a revision control system should probably read this manual's sections
-    regarding such development.  Alternately, you may wish to create a
-    quick-reference guide containing the tips from this manual that apply to
-    your particular situation.  For example, if you recommend that people use
-    ``setup.py develop`` when tracking your in-development code, you should let
-    them know that this needs to be run after every update or commit.
-
-    Similarly, if you remove modules or data files from your project, you
-    should remind them to run ``setup.py clean --all`` and delete any obsolete
-    ``.pyc`` or ``.pyo``.  (This tip applies to the distutils in general, not
-    just setuptools, but not everybody knows about them; be kind to your users
-    by spelling out your project's best practices rather than leaving them
-    guessing.)
-
-Creating System Packages
-    Some users want to manage all Python packages using a single package
-    manager, and sometimes that package manager isn't ``easy_install``!
-    Setuptools currently supports ``bdist_rpm``, ``bdist_wininst``, and
-    ``bdist_dumb`` formats for system packaging.  If a user has a locally-
-    installed "bdist" packaging tool that internally uses the distutils
-    ``install`` command, it should be able to work with ``setuptools``.  Some
-    examples of "bdist" formats that this should work with include the
-    ``bdist_nsi`` and ``bdist_msi`` formats for Windows.
-
-    However, packaging tools that build binary distributions by running
-    ``setup.py install`` on the command line or as a subprocess will require
-    modification to work with setuptools.  They should use the
-    ``--single-version-externally-managed`` option to the ``install`` command,
-    combined with the standard ``--root`` or ``--record`` options.
-    See the `install command`_ documentation below for more details.  The
-    ``bdist_deb`` command is an example of a command that currently requires
-    this kind of patching to work with setuptools.
-
-    Please note that building system packages may require you to install
-    some system software, for example ``bdist_rpm`` requires the ``rpmbuild``
-    command to be installed.
-
-    If you or your users have a problem building a usable system package for
-    your project, please report the problem via the mailing list so that
-    either the "bdist" tool in question or setuptools can be modified to
-    resolve the issue.
-
-Your users might not have ``setuptools`` installed on their machines, or even
-if they do, it might not be the right version.  Fixing this is easy; just
-download `ez_setup.py`_, and put it in the same directory as your ``setup.py``
-script.  (Be sure to add it to your revision control system, too.)  Then add
-these two lines to the very top of your setup script, before the script imports
-anything from setuptools:
-
-.. code-block:: python
-
-    import ez_setup
-    ez_setup.use_setuptools()
-
-That's it.  The ``ez_setup`` module will automatically download a matching
-version of ``setuptools`` from PyPI, if it isn't present on the target system.
-Whenever you install an updated version of setuptools, you should also update
-your projects' ``ez_setup.py`` files, so that a matching version gets installed
-on the target machine(s).
-
-(By the way, if you need to distribute a specific version of ``setuptools``,
-you can specify the exact version and base download URL as parameters to the
-``use_setuptools()`` function.  See the function's docstring for details.)
-
-.. _install command:
-
-``install`` - Run ``easy_install`` or old-style installation
-============================================================
-
-The setuptools ``install`` command is basically a shortcut to run the
-``easy_install`` command on the current project.  However, for convenience
-in creating "system packages" of setuptools-based projects, you can also
-use this option:
-
-``--single-version-externally-managed``
-    This boolean option tells the ``install`` command to perform an "old style"
-    installation, with the addition of an ``.egg-info`` directory so that the
-    installed project will still have its metadata available and operate
-    normally.  If you use this option, you *must* also specify the ``--root``
-    or ``--record`` options (or both), because otherwise you will have no way
-    to identify and remove the installed files.
-
-This option is automatically in effect when ``install`` is invoked by another
-distutils command, so that commands like ``bdist_wininst`` and ``bdist_rpm``
-will create system packages of eggs.  It is also automatically in effect if
-you specify the ``--root`` option.
-
-
-``install_egg_info`` - Install an ``.egg-info`` directory in ``site-packages``
-==============================================================================
-
-Setuptools runs this command as part of ``install`` operations that use the
-``--single-version-externally-managed`` options.  You should not invoke it
-directly; it is documented here for completeness and so that distutils
-extensions such as system package builders can make use of it.  This command
-has only one option:
-
-``--install-dir=DIR, -d DIR``
-    The parent directory where the ``.egg-info`` directory will be placed.
-    Defaults to the same as the ``--install-dir`` option specified for the
-    ``install_lib`` command, which is usually the system ``site-packages``
-    directory.
-
-This command assumes that the ``egg_info`` command has been given valid options
-via the command line or ``setup.cfg``, as it will invoke the ``egg_info``
-command and use its options to locate the project's source ``.egg-info``
-directory.
diff --git a/docs/formats.txt b/docs/formats.txt
index a182eb99..6c0456de 100644
--- a/docs/formats.txt
+++ b/docs/formats.txt
@@ -299,11 +299,8 @@ specified by the ``setup_requires`` parameter to the Distribution.
 A list of dependency URLs, one per line, as specified using the
 ``dependency_links`` keyword to ``setup()``.  These may be direct
 download URLs, or the URLs of web pages containing direct download
-links, and will be used by EasyInstall to find dependencies, as though
-the user had manually provided them via the ``--find-links`` command
-line option.  Please see the setuptools manual and EasyInstall manual
-for more information on specifying this option, and for information on
-how EasyInstall processes ``--find-links`` URLs.
+links. Please see the setuptools manual for more information on
+specifying this option.
 
 
 ``depends.txt`` -- Obsolete, do not create!
diff --git a/docs/pkg_resources.txt b/docs/pkg_resources.txt
index 806f1b14..b887a923 100644
--- a/docs/pkg_resources.txt
+++ b/docs/pkg_resources.txt
@@ -245,8 +245,8 @@ abbreviation for ``pkg_resources.working_set.require()``:
     interactive interpreter hacking than for production use. If you're creating
     an actual library or application, it's strongly recommended that you create
     a "setup.py" script using ``setuptools``, and declare all your requirements
-    there.  That way, tools like EasyInstall can automatically detect what
-    requirements your package has, and deal with them accordingly.
+    there.  That way, tools like pip can automatically detect what requirements
+    your package has, and deal with them accordingly.
 
     Note that calling ``require('SomePackage')`` will not install
     ``SomePackage`` if it isn't already present.  If you need to do this, you
@@ -611,9 +611,9 @@ Requirements Parsing
     or activation of both Report-O-Rama and any libraries it needs in order to
     provide PDF support.  For example, you could use::
 
-        easy_install.py Report-O-Rama[PDF]
+        pip install Report-O-Rama[PDF]
 
-    To install the necessary packages using the EasyInstall program, or call
+    To install the necessary packages using pip, or call
     ``pkg_resources.require('Report-O-Rama[PDF]')`` to add the necessary
     distributions to sys.path at runtime.
 
@@ -1843,9 +1843,9 @@ History
      because it isn't necessarily a filesystem path (and hasn't been for some
      time now).  The ``location`` of ``Distribution`` objects in the filesystem
      should always be normalized using ``pkg_resources.normalize_path()``; all
-     of the setuptools and EasyInstall code that generates distributions from
-     the filesystem (including ``Distribution.from_filename()``) ensure this
-     invariant, but if you use a more generic API like ``Distribution()`` or
+     of the setuptools' code that generates distributions from the filesystem
+     (including ``Distribution.from_filename()``) ensure this invariant, but if
+     you use a more generic API like ``Distribution()`` or
      ``Distribution.from_location()`` you should take care that you don't
      create a distribution with an un-normalized filesystem path.
 
diff --git a/docs/setuptools.txt b/docs/setuptools.txt
index ccbf069b..bc653b4a 100644
--- a/docs/setuptools.txt
+++ b/docs/setuptools.txt
@@ -8,23 +8,10 @@ distribute Python packages, especially ones that have dependencies on other
 packages.
 
 Packages built and distributed using ``setuptools`` look to the user like
-ordinary Python packages based on the ``distutils``.  Your users don't need to
-install or even know about setuptools in order to use them, and you don't
-have to include the entire setuptools package in your distributions.  By
-including just a single `bootstrap module`_ (a 12K .py file), your package will
-automatically download and install ``setuptools`` if the user is building your
-package from source and doesn't have a suitable version already installed.
-
-.. _bootstrap module: https://bootstrap.pypa.io/ez_setup.py
+ordinary Python packages based on the ``distutils``.
 
 Feature Highlights:
 
-* Automatically find/download/install/upgrade dependencies at build time using
-  the `EasyInstall tool <easy_install.html>`_,
-  which supports downloading via HTTP, FTP, Subversion, and SourceForge, and
-  automatically scans web pages linked from PyPI to find download links.  (It's
-  the closest thing to CPAN currently available for Python.)
-
 * Create `Python Eggs <http://peak.telecommunity.com/DevCenter/PythonEggs>`_ -
   a single-file importable distribution format
 
@@ -62,8 +49,6 @@ Feature Highlights:
 
 .. contents:: **Table of Contents**
 
-.. _ez_setup.py: `bootstrap module`_
-
 
 -----------------
 Developer's Guide
@@ -73,10 +58,6 @@ Developer's Guide
 Installing ``setuptools``
 =========================
 
-.. _EasyInstall Installation Instructions: easy_install.html
-
-.. _Custom Installation Locations: easy_install.html
-
 .. _Installing Packages: https://packaging.python.org/tutorials/installing-packages/
 
 To install the latest version of setuptools, use::
@@ -160,7 +141,7 @@ Specifying Your Project's Version
 
 Setuptools can work well with most versioning schemes; there are, however, a
 few special things to watch out for, in order to ensure that setuptools and
-EasyInstall can always tell what version of your package is newer than another
+other tools can always tell what version of your package is newer than another
 version.  Knowing these things will also help you correctly specify what
 versions of other projects your project depends on.
 
@@ -301,11 +282,10 @@ unless you need the associated ``setuptools`` feature.
 ``setup_requires``
     A string or list of strings specifying what other distributions need to
     be present in order for the *setup script* to run.  ``setuptools`` will
-    attempt to obtain these (even going so far as to download them using
-    ``EasyInstall``) before processing the rest of the setup script or commands.
-    This argument is needed if you are using distutils extensions as part of
-    your build process; for example, extensions that process setup() arguments
-    and turn them into EGG-INFO metadata files.
+    attempt to obtain these before processing the rest of the setup script or
+    commands.  This argument is needed if you are using distutils extensions as
+    part of your build process; for example, extensions that process setup()
+    arguments and turn them into EGG-INFO metadata files.
 
     (Note: projects listed in ``setup_requires`` will NOT be automatically
     installed on the system where the setup script is being run.  They are
@@ -318,8 +298,7 @@ unless you need the associated ``setuptools`` feature.
     A list of strings naming URLs to be searched when satisfying dependencies.
     These links will be used if needed to install packages specified by
     ``setup_requires`` or ``tests_require``.  They will also be written into
-    the egg's metadata for use by tools like EasyInstall to use when installing
-    an ``.egg`` file.
+    the egg's metadata for use during install by tools that support them.
 
 ``namespace_packages``
     A list of strings naming the project's "namespace packages".  A namespace
@@ -346,17 +325,20 @@ unless you need the associated ``setuptools`` feature.
     specified test suite, e.g. via ``setup.py test``.  See the section on the
     `test`_ command below for more details.
 
+    New in 41.5.0: Deprecated the test command.
+
 ``tests_require``
     If your project's tests need one or more additional packages besides those
     needed to install it, you can use this option to specify them.  It should
     be a string or list of strings specifying what other distributions need to
     be present for the package's tests to run.  When you run the ``test``
-    command, ``setuptools`` will  attempt to obtain these (even going
-    so far as to download them using ``EasyInstall``).  Note that these
+    command, ``setuptools`` will  attempt to obtain these.  Note that these
     required projects will *not* be installed on the system where the tests
     are run, but only downloaded to the project's setup directory if they're
     not already installed locally.
 
+    New in 41.5.0: Deprecated the test command.
+
 .. _test_loader:
 
 ``test_loader``
@@ -380,6 +362,8 @@ unless you need the associated ``setuptools`` feature.
     as long as you use the ``tests_require`` option to ensure that the package
     containing the loader class is available when the ``test`` command is run.
 
+    New in 41.5.0: Deprecated the test command.
+
 ``eager_resources``
     A list of strings naming resources that should be extracted together, if
     any of them is needed, or if any C extensions included in the project are
@@ -552,11 +536,12 @@ script called ``baz``, you might do something like this::
     )
 
 When this project is installed on non-Windows platforms (using "setup.py
-install", "setup.py develop", or by using EasyInstall), a set of ``foo``,
-``bar``, and ``baz`` scripts will be installed that import ``main_func`` and
-``some_func`` from the specified modules.  The functions you specify are called
-with no arguments, and their return value is passed to ``sys.exit()``, so you
-can return an errorlevel or message to print to stderr.
+install", "setup.py develop", or with pip), a set of ``foo``, ``bar``,
+and ``baz`` scripts will be installed that import ``main_func`` and
+``some_func`` from the specified modules.  The functions you specify are
+called with no arguments, and their return value is passed to
+``sys.exit()``, so you can return an errorlevel or message to print to
+stderr.
 
 On Windows, a set of ``foo.exe``, ``bar.exe``, and ``baz.exe`` launchers are
 created, alongside a set of ``foo.py``, ``bar.py``, and ``baz.pyw`` files.  The
@@ -596,10 +581,6 @@ Python must be available via the ``PATH`` environment variable, under its
 "long" name.  That is, if the egg is built for Python 2.3, there must be a
 ``python2.3`` executable present in a directory on ``PATH``.
 
-This feature is primarily intended to support ez_setup the installation of
-setuptools itself on non-Windows platforms, but may also be useful for other
-projects as well.
-
 IMPORTANT NOTE: Eggs with an "eggsecutable" header cannot be renamed, or
 invoked via symlinks.  They *must* be invoked using their original filename, in
 order to ensure that, once running, ``pkg_resources`` will know what project
@@ -613,7 +594,7 @@ Declaring Dependencies
 
 ``setuptools`` supports automatically installing dependencies when a package is
 installed, and including information about dependencies in Python Eggs (so that
-package management tools like EasyInstall can use the information).
+package management tools like pip can use the information).
 
 ``setuptools`` and ``pkg_resources`` use a common syntax for specifying a
 project's required dependencies.  This syntax consists of a project's PyPI
@@ -652,10 +633,9 @@ requirement in a string, each requirement must begin on a new line.
 
 This has three effects:
 
-1. When your project is installed, either by using EasyInstall, ``setup.py
-   install``, or ``setup.py develop``, all of the dependencies not already
-   installed will be located (via PyPI), downloaded, built (if necessary),
-   and installed.
+1. When your project is installed, either by using pip, ``setup.py install``,
+   or ``setup.py develop``, all of the dependencies not already installed will
+   be located (via PyPI), downloaded, built (if necessary), and installed.
 
 2. Any scripts in your project will be installed with wrappers that verify
    the availability of the specified dependencies at runtime, and ensure that
@@ -675,6 +655,10 @@ using ``setup.py develop``.)
 Dependencies that aren't in PyPI
 --------------------------------
 
+.. warning::
+    Dependency links support has been dropped by pip starting with version
+    19.0 (released 2019-01-22).
+
 If your project depends on packages that don't exist on PyPI, you may still be
 able to depend on them, as long as they are available for download as:
 
@@ -725,9 +709,8 @@ This will do a checkout (or a clone, in Git and Mercurial parlance) to a
 temporary folder and run ``setup.py bdist_egg``.
 
 The ``dependency_links`` option takes the form of a list of URL strings.  For
-example, the below will cause EasyInstall to search the specified page for
-eggs or source distributions, if the package's dependencies aren't already
-installed::
+example, this will cause a search of the specified page for eggs or source
+distributions, if the package's dependencies aren't already installed::
 
     setup(
         ...
@@ -767,7 +750,7 @@ names of "extra" features, to strings or lists of strings describing those
 features' requirements.  These requirements will *not* be automatically
 installed unless another package depends on them (directly or indirectly) by
 including the desired "extras" in square brackets after the associated project
-name.  (Or if the extras were listed in a requirement spec on the EasyInstall
+name.  (Or if the extras were listed in a requirement spec on the "pip install"
 command line.)
 
 Extras can be used by a project's `entry points`_ to specify dynamic
@@ -1182,13 +1165,12 @@ preferred way of working (as opposed to using a common independent staging area
 or the site-packages directory).
 
 To do this, use the ``setup.py develop`` command.  It works very similarly to
-``setup.py install`` or the EasyInstall tool, except that it doesn't actually
-install anything.  Instead, it creates a special ``.egg-link`` file in the
-deployment directory, that links to your project's source code.  And, if your
-deployment directory is Python's ``site-packages`` directory, it will also
-update the ``easy-install.pth`` file to include your project's source code,
-thereby making it available on ``sys.path`` for all programs using that Python
-installation.
+``setup.py install``, except that it doesn't actually install anything.
+Instead, it creates a special ``.egg-link`` file in the deployment directory,
+that links to your project's source code.  And, if your deployment directory is
+Python's ``site-packages`` directory, it will also update the
+``easy-install.pth`` file to include your project's source code, thereby making
+it available on ``sys.path`` for all programs using that Python installation.
 
 If you have enabled the ``use_2to3`` flag, then of course the ``.egg-link``
 will not link directly to your source code when run under Python 3, since
@@ -1259,20 +1241,6 @@ To install your newly uploaded package ``example_pkg``,  you can use pip::
 If you have issues at any point, please refer to `Packaging project tutorials`_
 for clarification.
 
-Distributing legacy ``setuptools`` projects using ez_setup.py
--------------------------------------------------------------
-
-.. warning:: **ez_setup** is deprecated in favor of PIP with **PEP-518** support.
-
-Distributing packages using the legacy ``ez_setup.py`` and ``easy_install`` is
-deprecated in favor of PIP. Please consider migrating to using pip and twine based
-distribution.
-
-However, if you still have any ``ez_setup`` based packages, documentation for
-ez_setup based distributions can be found at `ez_setup distribution guide`_.
-
-.. _ez_setup distribution guide: ez_setup.html
-
 Setting the ``zip_safe`` flag
 -----------------------------
 
@@ -1308,20 +1276,14 @@ you've checked over all the warnings it issued, and you are either satisfied it
 doesn't work, you can always change it to ``False``, which will force
 ``setuptools`` to install your project as a directory rather than as a zipfile.
 
-Of course, the end-user can still override either decision, if they are using
-EasyInstall to install your package.  And, if you want to override for testing
-purposes, you can just run ``setup.py easy_install --zip-ok .`` or ``setup.py
-easy_install --always-unzip .`` in your project directory. to install the
-package as a zipfile or directory, respectively.
-
 In the future, as we gain more experience with different packages and become
 more satisfied with the robustness of the ``pkg_resources`` runtime, the
 "zip safety" analysis may become less conservative.  However, we strongly
 recommend that you determine for yourself whether your project functions
 correctly when installed as a zipfile, correct any problems if you can, and
 then make an explicit declaration of ``True`` or ``False`` for the ``zip_safe``
-flag, so that it will not be necessary for ``bdist_egg`` or ``EasyInstall`` to
-try to guess whether your project can work as a zipfile.
+flag, so that it will not be necessary for ``bdist_egg`` to try to guess
+whether your project can work as a zipfile.
 
 .. _Namespace Packages:
 
@@ -1435,9 +1397,9 @@ to generate a daily build or snapshot for.  See the section below on the
 
 (Also, before you release your project, be sure to see the section above on
 `Specifying Your Project's Version`_ for more information about how pre- and
-post-release tags affect how setuptools and EasyInstall interpret version
-numbers.  This is important in order to make sure that dependency processing
-tools will know which versions of your project are newer than others.)
+post-release tags affect how version numbers are interpreted.  This is
+important in order to make sure that dependency processing tools will know
+which versions of your project are newer than others.)
 
 Finally, if you are creating builds frequently, and either building them in a
 downloadable location or are copying them to a distribution server, you should
@@ -1493,58 +1455,6 @@ all practical purposes, you'll probably use only the ``--formats`` option, if
 you use any option at all.
 
 
-Making your package available for EasyInstall
----------------------------------------------
-
-There may be reasons why you don't want to upload distributions to
-PyPI, and just want your existing distributions (or perhaps a Subversion
-checkout) to be used instead.
-
-There are three ``setup()`` arguments that affect EasyInstall:
-
-``url`` and ``download_url``
-   These become links on your project's PyPI page.  EasyInstall will examine
-   them to see if they link to a package ("primary links"), or whether they are
-   HTML pages.  If they're HTML pages, EasyInstall scans all HREF's on the
-   page for primary links
-
-``long_description``
-   EasyInstall will check any URLs contained in this argument to see if they
-   are primary links.
-
-A URL is considered a "primary link" if it is a link to a .tar.gz, .tgz, .zip,
-.egg, .egg.zip, .tar.bz2, or .exe file, or if it has an ``#egg=project`` or
-``#egg=project-version`` fragment identifier attached to it.  EasyInstall
-attempts to determine a project name and optional version number from the text
-of a primary link *without* downloading it.  When it has found all the primary
-links, EasyInstall will select the best match based on requested version,
-platform compatibility, and other criteria.
-
-So, if your ``url`` or ``download_url`` point either directly to a downloadable
-source distribution, or to HTML page(s) that have direct links to such, then
-EasyInstall will be able to locate downloads automatically.  If you want to
-make Subversion checkouts available, then you should create links with either
-``#egg=project`` or ``#egg=project-version`` added to the URL.  You should
-replace ``project`` and ``version`` with the values they would have in an egg
-filename.  (Be sure to actually generate an egg and then use the initial part
-of the filename, rather than trying to guess what the escaped form of the
-project name and version number will be.)
-
-Note that Subversion checkout links are of lower precedence than other kinds
-of distributions, so EasyInstall will not select a Subversion checkout for
-downloading unless it has a version included in the ``#egg=`` suffix, and
-it's a higher version than EasyInstall has seen in any other links for your
-project.
-
-As a result, it's a common practice to use mark checkout URLs with a version of
-"dev" (i.e., ``#egg=projectname-dev``), so that users can do something like
-this::
-
-    easy_install --editable projectname==dev
-
-in order to check out the in-development version of ``projectname``.
-
-
 Making "Official" (Non-Snapshot) Releases
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -1689,6 +1599,9 @@ file locations.
 ``bdist_egg`` - Create a Python Egg for the project
 ===================================================
 
+.. warning::
+    **eggs** are deprecated in favor of wheels, and not supported by pip.
+
 This command generates a Python Egg (``.egg`` file) for the project.  Python
 Eggs are the preferred binary distribution format for EasyInstall, because they
 are cross-platform (for "pure" packages), directly importable, and contain
@@ -1796,9 +1709,9 @@ Here are some of the options that the ``develop`` command accepts.  Note that
 they affect the project's dependencies as well as the project itself, so if you
 have dependencies that need to be installed and you use ``--exclude-scripts``
 (for example), the dependencies' scripts will not be installed either!  For
-this reason, you may want to use EasyInstall to install the project's
-dependencies before using the ``develop`` command, if you need finer control
-over the installation options for dependencies.
+this reason, you may want to use pip to install the project's dependencies
+before using the ``develop`` command, if you need finer control over the
+installation options for dependencies.
 
 ``--uninstall, -u``
     Un-deploy the current project.  You may use the ``--install-dir`` or ``-d``
@@ -1808,10 +1721,10 @@ over the installation options for dependencies.
     staging area is Python's ``site-packages`` directory.
 
     Note that this option currently does *not* uninstall script wrappers!  You
-    must uninstall them yourself, or overwrite them by using EasyInstall to
-    activate a different version of the package.  You can also avoid installing
-    script wrappers in the first place, if you use the ``--exclude-scripts``
-    (aka ``-x``) option when you run ``develop`` to deploy the project.
+    must uninstall them yourself, or overwrite them by using pip to install a
+    different version of the package.  You can also avoid installing script
+    wrappers in the first place, if you use the ``--exclude-scripts`` (aka
+    ``-x``) option when you run ``develop`` to deploy the project.
 
 ``--multi-version, -m``
     "Multi-version" mode. Specifying this option prevents ``develop`` from
@@ -1820,8 +1733,8 @@ over the installation options for dependencies.
     removed upon successful deployment.  In multi-version mode, no specific
     version of the package is available for importing, unless you use
     ``pkg_resources.require()`` to put it on ``sys.path``, or you are running
-    a wrapper script generated by ``setuptools`` or EasyInstall.  (In which
-    case the wrapper script calls ``require()`` for you.)
+    a wrapper script generated by ``setuptools``.  (In which case the wrapper
+    script calls ``require()`` for you.)
 
     Note that if you install to a directory other than ``site-packages``,
     this option is automatically in effect, because ``.pth`` files can only be
@@ -1874,25 +1787,6 @@ files), the ``develop`` command will use them as defaults, unless you override
 them in a ``[develop]`` section or on the command line.
 
 
-``easy_install`` - Find and install packages
-============================================
-
-This command runs the `EasyInstall tool
-<easy_install.html>`_ for you.  It is exactly
-equivalent to running the ``easy_install`` command.  All command line arguments
-following this command are consumed and not processed further by the distutils,
-so this must be the last command listed on the command line.  Please see
-the EasyInstall documentation for the options reference and usage examples.
-Normally, there is no reason to use this command via the command line, as you
-can just use ``easy_install`` directly.  It's only listed here so that you know
-it's a distutils command, which means that you can:
-
-* create command aliases that use it,
-* create distutils extensions that invoke it as a subcommand, and
-* configure options for it in your ``setup.cfg`` or other distutils config
-  files.
-
-
 .. _egg_info:
 
 ``egg_info`` - Create egg metadata and set build tags
@@ -1951,9 +1845,9 @@ added in the following order:
 (Note: Because these options modify the version number used for source and
 binary distributions of your project, you should first make sure that you know
 how the resulting version numbers will be interpreted by automated tools
-like EasyInstall.  See the section above on `Specifying Your Project's
-Version`_ for an explanation of pre- and post-release tags, as well as tips on
-how to choose and verify a versioning scheme for your your project.)
+like pip.  See the section above on `Specifying Your Project's Version`_ for an
+explanation of pre- and post-release tags, as well as tips on how to choose and
+verify a versioning scheme for your your project.)
 
 For advanced uses, there is one other option that can be set, to change the
 location of the project's ``.egg-info`` directory.  Commands that need to find
@@ -2135,6 +2029,11 @@ distutils configuration file the option will be added to (or removed from).
 ``test`` - Build package and run a unittest suite
 =================================================
 
+.. warning::
+    ``test`` is deprecated and will be removed in a future version. Users
+    looking for a generic test entry point independent of test runner are
+    encouraged to use `tox <https://tox.readthedocs.io>`_.
+
 When doing test-driven development, or running automated builds that need
 testing before they are deployed for downloading or use, it's often useful
 to be able to run a project's unit tests without actually deploying the project
@@ -2180,22 +2079,21 @@ available:
     If you did not set a ``test_suite`` in your ``setup()`` call, and do not
     provide a ``--test-suite`` option, an error will occur.
 
+New in 41.5.0: Deprecated the test command.
+
 
 .. _upload:
 
 ``upload`` - Upload source and/or egg distributions to PyPI
 ===========================================================
 
-.. warning::
-    **upload** is deprecated in favor of using `twine
-    <https://pypi.org/p/twine>`_
-
-The ``upload`` command is implemented and `documented
-<https://docs.python.org/3.1/distutils/uploading.html>`_
-in distutils.
+The ``upload`` command was deprecated in version 40.0 and removed in version
+42.0. Use `twine <https://pypi.org/p/twine>`_ instead.
 
-New in 20.1: Added keyring support.
-New in 40.0: Deprecated the upload command.
+For  more information on the current best practices in uploading your packages
+to PyPI, see the Python Packaging User Guide's "Packaging Python Projects"
+tutorial specifically the section on `uploading the distribution archives
+<https://packaging.python.org/tutorials/packaging-projects/#uploading-the-distribution-archives>`_.
 
 
 -----------------------------------------
@@ -2416,7 +2314,7 @@ tests_require            list-semi
 include_package_data     bool
 packages                 find:, find_namespace:, list-comma
 package_dir              dict
-package_data             section
+package_data             section                                              (1)
 exclude_package_data     section
 namespace_packages       list-comma
 py_modules               list-comma
@@ -2433,6 +2331,10 @@ data_files               dict                                 40.6.0
 
     **find_namespace directive** - The ``find_namespace:`` directive is supported since Python >=3.3.
 
+Notes:
+1. In the `package_data` section, a key named with a single asterisk (`*`)
+refers to all packages, in lieu of the empty string used in `setup.py`.
+
 
 Configuration API
 =================
diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py
index 1f170cfd..51fb1192 100644
--- a/pkg_resources/__init__.py
+++ b/pkg_resources/__init__.py
@@ -333,7 +333,7 @@ class UnknownExtra(ResolutionError):
 
 _provider_factories = {}
 
-PY_MAJOR = sys.version[:3]
+PY_MAJOR = '{}.{}'.format(*sys.version_info)
 EGG_DIST = 3
 BINARY_DIST = 2
 SOURCE_DIST = 1
@@ -3109,6 +3109,7 @@ class Requirement(packaging.requirements.Requirement):
         self.extras = tuple(map(safe_extra, self.extras))
         self.hashCmp = (
             self.key,
+            self.url,
             self.specifier,
             frozenset(self.extras),
             str(self.marker) if self.marker else None,
diff --git a/pkg_resources/api_tests.txt b/pkg_resources/api_tests.txt
index 0a75170e..7ae5a038 100644
--- a/pkg_resources/api_tests.txt
+++ b/pkg_resources/api_tests.txt
@@ -36,7 +36,7 @@ Distributions have various introspectable attributes::
     >>> dist.version
     '0.9'
 
-    >>> dist.py_version == sys.version[:3]
+    >>> dist.py_version == '{}.{}'.format(*sys.version_info)
     True
 
     >>> print(dist.platform)
diff --git a/pkg_resources/tests/data/my-test-package-source/setup.cfg b/pkg_resources/tests/data/my-test-package-source/setup.cfg
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package-source/setup.cfg
diff --git a/pkg_resources/tests/data/my-test-package-source/setup.py b/pkg_resources/tests/data/my-test-package-source/setup.py
new file mode 100644
index 00000000..fe80d28f
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package-source/setup.py
@@ -0,0 +1,6 @@
+import setuptools
+setuptools.setup(
+    name="my-test-package",
+    version="1.0",
+    zip_safe=True,
+)
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO
new file mode 100644
index 00000000..7328e3f7
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO
@@ -0,0 +1,10 @@
+Metadata-Version: 1.0
+Name: my-test-package
+Version: 1.0
+Summary: UNKNOWN
+Home-page: UNKNOWN
+Author: UNKNOWN
+Author-email: UNKNOWN
+License: UNKNOWN
+Description: UNKNOWN
+Platform: UNKNOWN
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt
new file mode 100644
index 00000000..3c4ee167
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt
@@ -0,0 +1,7 @@
+setup.cfg
+setup.py
+my_test_package.egg-info/PKG-INFO
+my_test_package.egg-info/SOURCES.txt
+my_test_package.egg-info/dependency_links.txt
+my_test_package.egg-info/top_level.txt
+my_test_package.egg-info/zip-safe
\ No newline at end of file
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg b/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg
new file mode 100644
index 00000000..5115b895
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg
diff --git a/pkg_resources/tests/test_find_distributions.py b/pkg_resources/tests/test_find_distributions.py
index d735c590..f9594422 100644
--- a/pkg_resources/tests/test_find_distributions.py
+++ b/pkg_resources/tests/test_find_distributions.py
@@ -1,17 +1,9 @@
-import subprocess
-import sys
-
+import py
 import pytest
 import pkg_resources
 
-SETUP_TEMPLATE = """
-import setuptools
-setuptools.setup(
-    name="my-test-package",
-    version="1.0",
-    zip_safe=True,
-)
-""".lstrip()
+
+TESTS_DATA_DIR = py.path.local(__file__).dirpath('data')
 
 
 class TestFindDistributions:
@@ -21,46 +13,22 @@ class TestFindDistributions:
         target_dir = tmpdir.mkdir('target')
         # place a .egg named directory in the target that is not an egg:
         target_dir.mkdir('not.an.egg')
-        return str(target_dir)
-
-    @pytest.fixture
-    def project_dir(self, tmpdir):
-        project_dir = tmpdir.mkdir('my-test-package')
-        (project_dir / "setup.py").write(SETUP_TEMPLATE)
-        return str(project_dir)
+        return target_dir
 
     def test_non_egg_dir_named_egg(self, target_dir):
-        dists = pkg_resources.find_distributions(target_dir)
+        dists = pkg_resources.find_distributions(str(target_dir))
         assert not list(dists)
 
-    def test_standalone_egg_directory(self, project_dir, target_dir):
-        # install this distro as an unpacked egg:
-        args = [
-            sys.executable,
-            '-c', 'from setuptools.command.easy_install import main; main()',
-            '-mNx',
-            '-d', target_dir,
-            '--always-unzip',
-            project_dir,
-        ]
-        subprocess.check_call(args)
-        dists = pkg_resources.find_distributions(target_dir)
+    def test_standalone_egg_directory(self, target_dir):
+        (TESTS_DATA_DIR / 'my-test-package_unpacked-egg').copy(target_dir)
+        dists = pkg_resources.find_distributions(str(target_dir))
         assert [dist.project_name for dist in dists] == ['my-test-package']
-        dists = pkg_resources.find_distributions(target_dir, only=True)
+        dists = pkg_resources.find_distributions(str(target_dir), only=True)
         assert not list(dists)
 
-    def test_zipped_egg(self, project_dir, target_dir):
-        # install this distro as an unpacked egg:
-        args = [
-            sys.executable,
-            '-c', 'from setuptools.command.easy_install import main; main()',
-            '-mNx',
-            '-d', target_dir,
-            '--zip-ok',
-            project_dir,
-        ]
-        subprocess.check_call(args)
-        dists = pkg_resources.find_distributions(target_dir)
+    def test_zipped_egg(self, target_dir):
+        (TESTS_DATA_DIR / 'my-test-package_zipped-egg').copy(target_dir)
+        dists = pkg_resources.find_distributions(str(target_dir))
         assert [dist.project_name for dist in dists] == ['my-test-package']
-        dists = pkg_resources.find_distributions(target_dir, only=True)
+        dists = pkg_resources.find_distributions(str(target_dir), only=True)
         assert not list(dists)
diff --git a/pkg_resources/tests/test_resources.py b/pkg_resources/tests/test_resources.py
index 86afcf74..93fa7114 100644
--- a/pkg_resources/tests/test_resources.py
+++ b/pkg_resources/tests/test_resources.py
@@ -116,7 +116,7 @@ class TestDistro:
         self.checkFooPkg(d)
 
         d = Distribution("/some/path")
-        assert d.py_version == sys.version[:3]
+        assert d.py_version == '{}.{}'.format(*sys.version_info)
         assert d.platform is None
 
     def testDistroParse(self):
@@ -520,6 +520,11 @@ class TestRequirements:
         assert r1 == r2
         assert str(r1) == str(r2)
         assert str(r2) == "Twisted==1.2c1,>=1.2"
+        assert (
+            Requirement("Twisted")
+            !=
+            Requirement("Twisted @ https://localhost/twisted.zip")
+        )
 
     def testBasicContains(self):
         r = Requirement("Twisted>=1.2")
@@ -546,11 +551,23 @@ class TestRequirements:
             ==
             hash((
                 "twisted",
+                None,
                 packaging.specifiers.SpecifierSet(">=1.2"),
                 frozenset(["foo", "bar"]),
                 None
             ))
         )
+        assert (
+            hash(Requirement.parse("Twisted @ https://localhost/twisted.zip"))
+            ==
+            hash((
+                "twisted",
+                "https://localhost/twisted.zip",
+                packaging.specifiers.SpecifierSet(),
+                frozenset(),
+                None
+            ))
+        )
 
     def testVersionEquality(self):
         r1 = Requirement.parse("foo==0.3a2")
diff --git a/pytest.ini b/pytest.ini
index 612fb91f..0bc1ec01 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,7 +1,10 @@
 [pytest]
 addopts=--doctest-modules --doctest-glob=pkg_resources/api_tests.txt -r sxX
-norecursedirs=dist build *.egg setuptools/extern pkg_resources/extern .*
+norecursedirs=dist build *.egg setuptools/extern pkg_resources/extern pkg_resources/tests/data tools .*
 flake8-ignore =
     setuptools/site-patch.py F821
     setuptools/py*compat.py F811
 doctest_optionflags=ELLIPSIS ALLOW_UNICODE
+filterwarnings =
+	# https://github.com/pypa/setuptools/issues/1823
+	ignore:bdist_wininst command is deprecated
diff --git a/setup.cfg b/setup.cfg
index a55106a5..42a3d86c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -19,7 +19,7 @@ universal = 1
 
 [metadata]
 name = setuptools
-version = 41.4.0
+version = 41.6.0
 description = Easily download, build, install, upgrade, and uninstall Python packages
 author = Python Packaging Authority
 author_email = distutils-sig@python.org
@@ -42,6 +42,7 @@ classifiers =
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
     Topic :: Software Development :: Libraries :: Python Modules
     Topic :: System :: Archiving :: Packaging
     Topic :: System :: Systems Administration
diff --git a/setup.py b/setup.py
index ac56a1b0..277b6640 100755
--- a/setup.py
+++ b/setup.py
@@ -44,7 +44,7 @@ def _gen_console_scripts():
     if any(os.environ.get(var) not in (None, "", "0") for var in var_names):
         return
     tmpl = "easy_install-{shortver} = setuptools.command.easy_install:main"
-    yield tmpl.format(shortver=sys.version[:3])
+    yield tmpl.format(shortver='{}.{}'.format(*sys.version_info))
 
 
 package_data = dict(
diff --git a/setuptools/_imp.py b/setuptools/_imp.py
new file mode 100644
index 00000000..a3cce9b2
--- /dev/null
+++ b/setuptools/_imp.py
@@ -0,0 +1,73 @@
+"""
+Re-implementation of find_module and get_frozen_object
+from the deprecated imp module.
+"""
+
+import os
+import importlib.util
+import importlib.machinery
+
+from .py34compat import module_from_spec
+
+
+PY_SOURCE = 1
+PY_COMPILED = 2
+C_EXTENSION = 3
+C_BUILTIN = 6
+PY_FROZEN = 7
+
+
+def find_module(module, paths=None):
+    """Just like 'imp.find_module()', but with package support"""
+    spec = importlib.util.find_spec(module, paths)
+    if spec is None:
+        raise ImportError("Can't find %s" % module)
+    if not spec.has_location and hasattr(spec, 'submodule_search_locations'):
+        spec = importlib.util.spec_from_loader('__init__.py', spec.loader)
+
+    kind = -1
+    file = None
+    static = isinstance(spec.loader, type)
+    if spec.origin == 'frozen' or static and issubclass(
+            spec.loader, importlib.machinery.FrozenImporter):
+        kind = PY_FROZEN
+        path = None  # imp compabilty
+        suffix = mode = ''  # imp compability
+    elif spec.origin == 'built-in' or static and issubclass(
+            spec.loader, importlib.machinery.BuiltinImporter):
+        kind = C_BUILTIN
+        path = None  # imp compabilty
+        suffix = mode = ''  # imp compability
+    elif spec.has_location:
+        path = spec.origin
+        suffix = os.path.splitext(path)[1]
+        mode = 'r' if suffix in importlib.machinery.SOURCE_SUFFIXES else 'rb'
+
+        if suffix in importlib.machinery.SOURCE_SUFFIXES:
+            kind = PY_SOURCE
+        elif suffix in importlib.machinery.BYTECODE_SUFFIXES:
+            kind = PY_COMPILED
+        elif suffix in importlib.machinery.EXTENSION_SUFFIXES:
+            kind = C_EXTENSION
+
+        if kind in {PY_SOURCE, PY_COMPILED}:
+            file = open(path, mode)
+    else:
+        path = None
+        suffix = mode = ''
+
+    return file, path, (suffix, mode, kind)
+
+
+def get_frozen_object(module, paths=None):
+    spec = importlib.util.find_spec(module, paths)
+    if not spec:
+        raise ImportError("Can't find %s" % module)
+    return spec.loader.get_code(module)
+
+
+def get_module(module, paths, info):
+    spec = importlib.util.find_spec(module, paths)
+    if not spec:
+        raise ImportError("Can't find %s" % module)
+    return module_from_spec(spec)
diff --git a/setuptools/_vendor/vendored.txt b/setuptools/_vendor/vendored.txt
index 379aae56..5731b424 100644
--- a/setuptools/_vendor/vendored.txt
+++ b/setuptools/_vendor/vendored.txt
@@ -1,4 +1,4 @@
 packaging==16.8
 pyparsing==2.2.1
 six==1.10.0
-ordered-set
+ordered-set==3.1.1
diff --git a/setuptools/command/__init__.py b/setuptools/command/__init__.py
index fe619e2e..743f5588 100644
--- a/setuptools/command/__init__.py
+++ b/setuptools/command/__init__.py
@@ -2,8 +2,7 @@ __all__ = [
     'alias', 'bdist_egg', 'bdist_rpm', 'build_ext', 'build_py', 'develop',
     'easy_install', 'egg_info', 'install', 'install_lib', 'rotate', 'saveopts',
     'sdist', 'setopt', 'test', 'install_egg_info', 'install_scripts',
-    'register', 'bdist_wininst', 'upload_docs', 'upload', 'build_clib',
-    'dist_info',
+    'bdist_wininst', 'upload_docs', 'build_clib', 'dist_info',
 ]
 
 from distutils.command.bdist import bdist
diff --git a/setuptools/command/bdist_egg.py b/setuptools/command/bdist_egg.py
index 9f8df917..98470f17 100644
--- a/setuptools/command/bdist_egg.py
+++ b/setuptools/command/bdist_egg.py
@@ -284,7 +284,7 @@ class bdist_egg(Command):
                 "or refer to a module" % (ep,)
             )
 
-        pyver = sys.version[:3]
+        pyver = '{}.{}'.format(*sys.version_info)
         pkg = ep.module_name
         full = '.'.join(ep.attrs)
         base = ep.attrs[0]
diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
index 06c98271..545c3c44 100644
--- a/setuptools/command/easy_install.py
+++ b/setuptools/command/easy_install.py
@@ -241,7 +241,7 @@ class easy_install(Command):
         """
         Render the Setuptools version and installation details, then exit.
         """
-        ver = sys.version[:3]
+        ver = '{}.{}'.format(*sys.version_info)
         dist = get_distribution('setuptools')
         tmpl = 'setuptools {dist.version} from {dist.location} (Python {ver})'
         print(tmpl.format(**locals()))
@@ -1180,8 +1180,7 @@ class easy_install(Command):
         # to the setup.cfg file.
         ei_opts = self.distribution.get_option_dict('easy_install').copy()
         fetch_directives = (
-            'find_links', 'site_dirs', 'index_url', 'optimize',
-            'site_dirs', 'allow_hosts',
+            'find_links', 'site_dirs', 'index_url', 'optimize', 'allow_hosts',
         )
         fetch_options = {}
         for key, val in ei_opts.items():
@@ -1412,7 +1411,7 @@ def get_site_dirs():
                     os.path.join(
                         prefix,
                         "lib",
-                        "python" + sys.version[:3],
+                        "python{}.{}".format(*sys.version_info),
                         "site-packages",
                     ),
                     os.path.join(prefix, "lib", "site-python"),
@@ -1433,7 +1432,7 @@ def get_site_dirs():
                             home,
                             'Library',
                             'Python',
-                            sys.version[:3],
+                            '{}.{}'.format(*sys.version_info),
                             'site-packages',
                         )
                         sitedirs.append(home_sp)
diff --git a/setuptools/command/register.py b/setuptools/command/register.py
index 98bc0156..b8266b9a 100644
--- a/setuptools/command/register.py
+++ b/setuptools/command/register.py
@@ -1,18 +1,18 @@
 from distutils import log
 import distutils.command.register as orig
 
+from setuptools.errors import RemovedCommandError
+
 
 class register(orig.register):
-    __doc__ = orig.register.__doc__
+    """Formerly used to register packages on PyPI."""
 
     def run(self):
-        try:
-            # Make sure that we are using valid current name/version info
-            self.run_command('egg_info')
-            orig.register.run(self)
-        finally:
-            self.announce(
-                "WARNING: Registering is deprecated, use twine to "
-                "upload instead (https://pypi.org/p/twine/)",
-                log.WARN
-            )
+        msg = (
+            "The register command has been removed, use twine to upload "
+            + "instead (https://pypi.org/p/twine)"
+        )
+
+        self.announce("ERROR: " + msg, log.ERROR)
+
+        raise RemovedCommandError(msg)
diff --git a/setuptools/command/test.py b/setuptools/command/test.py
index 973e4eb2..c148b38d 100644
--- a/setuptools/command/test.py
+++ b/setuptools/command/test.py
@@ -74,7 +74,7 @@ class NonDataProperty:
 class test(Command):
     """Command to run unit tests after in-place build"""
 
-    description = "run unit tests after in-place build"
+    description = "run unit tests after in-place build (deprecated)"
 
     user_options = [
         ('test-module=', 'm', "Run 'test_suite' in specified module"),
@@ -214,6 +214,14 @@ class test(Command):
         return itertools.chain(ir_d, tr_d, er_d)
 
     def run(self):
+        self.announce(
+            "WARNING: Testing via this command is deprecated and will be "
+            "removed in a future version. Users looking for a generic test "
+            "entry point independent of test runner are encouraged to use "
+            "tox.",
+            log.WARN,
+        )
+
         installed_dists = self.install_dists(self.distribution)
 
         cmd = ' '.join(self._argv)
diff --git a/setuptools/command/upload.py b/setuptools/command/upload.py
index 6db8888b..ec7f81e2 100644
--- a/setuptools/command/upload.py
+++ b/setuptools/command/upload.py
@@ -1,196 +1,17 @@
-import io
-import os
-import hashlib
-import getpass
-
-from base64 import standard_b64encode
-
 from distutils import log
 from distutils.command import upload as orig
-from distutils.spawn import spawn
-
-from distutils.errors import DistutilsError
 
-from setuptools.extern.six.moves.urllib.request import urlopen, Request
-from setuptools.extern.six.moves.urllib.error import HTTPError
-from setuptools.extern.six.moves.urllib.parse import urlparse
+from setuptools.errors import RemovedCommandError
 
 
 class upload(orig.upload):
-    """
-    Override default upload behavior to obtain password
-    in a variety of different ways.
-    """
-    def run(self):
-        try:
-            orig.upload.run(self)
-        finally:
-            self.announce(
-                "WARNING: Uploading via this command is deprecated, use twine "
-                "to upload instead (https://pypi.org/p/twine/)",
-                log.WARN
-            )
+    """Formerly used to upload packages to PyPI."""
 
-    def finalize_options(self):
-        orig.upload.finalize_options(self)
-        self.username = (
-            self.username or
-            getpass.getuser()
-        )
-        # Attempt to obtain password. Short circuit evaluation at the first
-        # sign of success.
-        self.password = (
-            self.password or
-            self._load_password_from_keyring() or
-            self._prompt_for_password()
+    def run(self):
+        msg = (
+            "The upload command has been removed, use twine to upload "
+            + "instead (https://pypi.org/p/twine)"
         )
 
-    def upload_file(self, command, pyversion, filename):
-        # Makes sure the repository URL is compliant
-        schema, netloc, url, params, query, fragments = \
-            urlparse(self.repository)
-        if params or query or fragments:
-            raise AssertionError("Incompatible url %s" % self.repository)
-
-        if schema not in ('http', 'https'):
-            raise AssertionError("unsupported schema " + schema)
-
-        # Sign if requested
-        if self.sign:
-            gpg_args = ["gpg", "--detach-sign", "-a", filename]
-            if self.identity:
-                gpg_args[2:2] = ["--local-user", self.identity]
-            spawn(gpg_args,
-                  dry_run=self.dry_run)
-
-        # Fill in the data - send all the meta-data in case we need to
-        # register a new release
-        with open(filename, 'rb') as f:
-            content = f.read()
-
-        meta = self.distribution.metadata
-
-        data = {
-            # action
-            ':action': 'file_upload',
-            'protocol_version': '1',
-
-            # identify release
-            'name': meta.get_name(),
-            'version': meta.get_version(),
-
-            # file content
-            'content': (os.path.basename(filename), content),
-            'filetype': command,
-            'pyversion': pyversion,
-            'md5_digest': hashlib.md5(content).hexdigest(),
-
-            # additional meta-data
-            'metadata_version': str(meta.get_metadata_version()),
-            'summary': meta.get_description(),
-            'home_page': meta.get_url(),
-            'author': meta.get_contact(),
-            'author_email': meta.get_contact_email(),
-            'license': meta.get_licence(),
-            'description': meta.get_long_description(),
-            'keywords': meta.get_keywords(),
-            'platform': meta.get_platforms(),
-            'classifiers': meta.get_classifiers(),
-            'download_url': meta.get_download_url(),
-            # PEP 314
-            'provides': meta.get_provides(),
-            'requires': meta.get_requires(),
-            'obsoletes': meta.get_obsoletes(),
-            }
-
-        data['comment'] = ''
-
-        if self.sign:
-            data['gpg_signature'] = (os.path.basename(filename) + ".asc",
-                                     open(filename+".asc", "rb").read())
-
-        # set up the authentication
-        user_pass = (self.username + ":" + self.password).encode('ascii')
-        # The exact encoding of the authentication string is debated.
-        # Anyway PyPI only accepts ascii for both username or password.
-        auth = "Basic " + standard_b64encode(user_pass).decode('ascii')
-
-        # Build up the MIME payload for the POST data
-        boundary = '--------------GHSKFJDLGDS7543FJKLFHRE75642756743254'
-        sep_boundary = b'\r\n--' + boundary.encode('ascii')
-        end_boundary = sep_boundary + b'--\r\n'
-        body = io.BytesIO()
-        for key, value in data.items():
-            title = '\r\nContent-Disposition: form-data; name="%s"' % key
-            # handle multiple entries for the same name
-            if not isinstance(value, list):
-                value = [value]
-            for value in value:
-                if type(value) is tuple:
-                    title += '; filename="%s"' % value[0]
-                    value = value[1]
-                else:
-                    value = str(value).encode('utf-8')
-                body.write(sep_boundary)
-                body.write(title.encode('utf-8'))
-                body.write(b"\r\n\r\n")
-                body.write(value)
-        body.write(end_boundary)
-        body = body.getvalue()
-
-        msg = "Submitting %s to %s" % (filename, self.repository)
-        self.announce(msg, log.INFO)
-
-        # build the Request
-        headers = {
-            'Content-type': 'multipart/form-data; boundary=%s' % boundary,
-            'Content-length': str(len(body)),
-            'Authorization': auth,
-        }
-
-        request = Request(self.repository, data=body,
-                          headers=headers)
-        # send the data
-        try:
-            result = urlopen(request)
-            status = result.getcode()
-            reason = result.msg
-        except HTTPError as e:
-            status = e.code
-            reason = e.msg
-        except OSError as e:
-            self.announce(str(e), log.ERROR)
-            raise
-
-        if status == 200:
-            self.announce('Server response (%s): %s' % (status, reason),
-                          log.INFO)
-            if self.show_response:
-                text = getattr(self, '_read_pypi_response',
-                               lambda x: None)(result)
-                if text is not None:
-                    msg = '\n'.join(('-' * 75, text, '-' * 75))
-                    self.announce(msg, log.INFO)
-        else:
-            msg = 'Upload failed (%s): %s' % (status, reason)
-            self.announce(msg, log.ERROR)
-            raise DistutilsError(msg)
-
-    def _load_password_from_keyring(self):
-        """
-        Attempt to load password from keyring. Suppress Exceptions.
-        """
-        try:
-            keyring = __import__('keyring')
-            return keyring.get_password(self.repository, self.username)
-        except Exception:
-            pass
-
-    def _prompt_for_password(self):
-        """
-        Prompt for a password on the tty. Suppress Exceptions.
-        """
-        try:
-            return getpass.getpass()
-        except (Exception, KeyboardInterrupt):
-            pass
+        self.announce("ERROR: " + msg, log.ERROR)
+        raise RemovedCommandError(msg)
diff --git a/setuptools/depends.py b/setuptools/depends.py
index 45e7052d..a37675cb 100644
--- a/setuptools/depends.py
+++ b/setuptools/depends.py
@@ -1,11 +1,13 @@
 import sys
-import imp
 import marshal
+import contextlib
 from distutils.version import StrictVersion
-from imp import PKG_DIRECTORY, PY_COMPILED, PY_SOURCE, PY_FROZEN
 
 from .py33compat import Bytecode
 
+from .py27compat import find_module, PY_COMPILED, PY_FROZEN, PY_SOURCE
+from . import py27compat
+
 
 __all__ = [
     'Require', 'find_module', 'get_module_constant', 'extract_constant'
@@ -15,7 +17,8 @@ __all__ = [
 class Require:
     """A prerequisite to building or installing a distribution"""
 
-    def __init__(self, name, requested_version, module, homepage='',
+    def __init__(
+            self, name, requested_version, module, homepage='',
             attribute=None, format=None):
 
         if format is None and requested_version is not None:
@@ -79,23 +82,15 @@ class Require:
         return self.version_ok(version)
 
 
-def find_module(module, paths=None):
-    """Just like 'imp.find_module()', but with package support"""
-
-    parts = module.split('.')
-
-    while parts:
-        part = parts.pop(0)
-        f, path, (suffix, mode, kind) = info = imp.find_module(part, paths)
-
-        if kind == PKG_DIRECTORY:
-            parts = parts or ['__init__']
-            paths = [path]
-
-        elif parts:
-            raise ImportError("Can't find %r in %s" % (parts, module))
+def maybe_close(f):
+    @contextlib.contextmanager
+    def empty():
+        yield
+        return
+    if not f:
+        return empty()
 
-    return info
+    return contextlib.closing(f)
 
 
 def get_module_constant(module, symbol, default=-1, paths=None):
@@ -106,28 +101,23 @@ def get_module_constant(module, symbol, default=-1, paths=None):
     constant.  Otherwise, return 'default'."""
 
     try:
-        f, path, (suffix, mode, kind) = find_module(module, paths)
+        f, path, (suffix, mode, kind) = info = find_module(module, paths)
     except ImportError:
         # Module doesn't exist
         return None
 
-    try:
+    with maybe_close(f):
         if kind == PY_COMPILED:
             f.read(8)  # skip magic & date
             code = marshal.load(f)
         elif kind == PY_FROZEN:
-            code = imp.get_frozen_object(module)
+            code = py27compat.get_frozen_object(module, paths)
         elif kind == PY_SOURCE:
             code = compile(f.read(), path, 'exec')
         else:
             # Not something we can parse; we'll have to import it.  :(
-            if module not in sys.modules:
-                imp.load_module(module, f, path, (suffix, mode, kind))
-            return getattr(sys.modules[module], symbol, None)
-
-    finally:
-        if f:
-            f.close()
+            imported = py27compat.get_module(module, paths, info)
+            return getattr(imported, symbol, None)
 
     return extract_constant(code, symbol, default)
 
diff --git a/setuptools/errors.py b/setuptools/errors.py
new file mode 100644
index 00000000..2701747f
--- /dev/null
+++ b/setuptools/errors.py
@@ -0,0 +1,16 @@
+"""setuptools.errors
+
+Provides exceptions used by setuptools modules.
+"""
+
+from distutils.errors import DistutilsError
+
+
+class RemovedCommandError(DistutilsError, RuntimeError):
+    """Error used for commands that have been removed in setuptools.
+
+    Since ``setuptools`` is built on ``distutils``, simply removing a command
+    from ``setuptools`` will make the behavior fall back to ``distutils``; this
+    error is raised if a command exists in ``distutils`` but has been actively
+    removed in ``setuptools``.
+    """
diff --git a/setuptools/msvc.py b/setuptools/msvc.py
index b9c472f1..2ffe1c81 100644
--- a/setuptools/msvc.py
+++ b/setuptools/msvc.py
@@ -11,13 +11,18 @@ Microsoft Visual C++ 9.0:
 Microsoft Visual C++ 10.0:
     Microsoft Windows SDK 7.1 (x86, x64, ia64)
 
-Microsoft Visual C++ 14.0:
+Microsoft Visual C++ 14.X:
     Microsoft Visual C++ Build Tools 2015 (x86, x64, arm)
-    Microsoft Visual Studio 2017 (x86, x64, arm, arm64)
     Microsoft Visual Studio Build Tools 2017 (x86, x64, arm, arm64)
+    Microsoft Visual Studio Build Tools 2019 (x86, x64, arm, arm64)
+
+This may also support compilers shipped with compatible Visual Studio versions.
 """
 
-import os
+import json
+from io import open
+from os import listdir, pathsep
+from os.path import join, isfile, isdir, dirname
 import sys
 import platform
 import itertools
@@ -30,12 +35,9 @@ from .monkey import get_unpatched
 
 if platform.system() == 'Windows':
     from setuptools.extern.six.moves import winreg
-    safe_env = os.environ
+    from os import environ
 else:
-    """
-    Mock winreg and environ so the module can be imported
-    on this platform.
-    """
+    # Mock winreg and environ so the module can be imported on this platform.
 
     class winreg:
         HKEY_USERS = None
@@ -43,7 +45,7 @@ else:
         HKEY_LOCAL_MACHINE = None
         HKEY_CLASSES_ROOT = None
 
-    safe_env = dict()
+    environ = dict()
 
 _msvc9_suppress_errors = (
     # msvc9compiler isn't available on some platforms
@@ -63,15 +65,13 @@ except _msvc9_suppress_errors:
 def msvc9_find_vcvarsall(version):
     """
     Patched "distutils.msvc9compiler.find_vcvarsall" to use the standalone
-    compiler build for Python (VCForPython). Fall back to original behavior
-    when the standalone compiler is not available.
+    compiler build for Python
+    (VCForPython / Microsoft Visual C++ Compiler for Python 2.7).
 
-    Redirect the path of "vcvarsall.bat".
+    Fall back to original behavior when the standalone compiler is not
+    available.
 
-    Known supported compilers
-    -------------------------
-    Microsoft Visual C++ 9.0:
-        Microsoft Visual C++ Compiler for Python 2.7 (x86, amd64)
+    Redirect the path of "vcvarsall.bat".
 
     Parameters
     ----------
@@ -80,24 +80,25 @@ def msvc9_find_vcvarsall(version):
 
     Return
     ------
-    vcvarsall.bat path: str
+    str
+        vcvarsall.bat path
     """
-    VC_BASE = r'Software\%sMicrosoft\DevDiv\VCForPython\%0.1f'
-    key = VC_BASE % ('', version)
+    vc_base = r'Software\%sMicrosoft\DevDiv\VCForPython\%0.1f'
+    key = vc_base % ('', version)
     try:
         # Per-user installs register the compiler path here
         productdir = Reg.get_value(key, "installdir")
     except KeyError:
         try:
             # All-user installs on a 64-bit system register here
-            key = VC_BASE % ('Wow6432Node\\', version)
+            key = vc_base % ('Wow6432Node\\', version)
             productdir = Reg.get_value(key, "installdir")
         except KeyError:
             productdir = None
 
     if productdir:
-        vcvarsall = os.path.os.path.join(productdir, "vcvarsall.bat")
-        if os.path.isfile(vcvarsall):
+        vcvarsall = join(productdir, "vcvarsall.bat")
+        if isfile(vcvarsall):
             return vcvarsall
 
     return get_unpatched(msvc9_find_vcvarsall)(version)
@@ -106,20 +107,10 @@ def msvc9_find_vcvarsall(version):
 def msvc9_query_vcvarsall(ver, arch='x86', *args, **kwargs):
     """
     Patched "distutils.msvc9compiler.query_vcvarsall" for support extra
-    compilers.
+    Microsoft Visual C++ 9.0 and 10.0 compilers.
 
     Set environment without use of "vcvarsall.bat".
 
-    Known supported compilers
-    -------------------------
-    Microsoft Visual C++ 9.0:
-        Microsoft Visual C++ Compiler for Python 2.7 (x86, amd64)
-        Microsoft Windows SDK 6.1 (x86, x64, ia64)
-        Microsoft Windows SDK 7.0 (x86, x64, ia64)
-
-    Microsoft Visual C++ 10.0:
-        Microsoft Windows SDK 7.1 (x86, x64, ia64)
-
     Parameters
     ----------
     ver: float
@@ -129,9 +120,10 @@ def msvc9_query_vcvarsall(ver, arch='x86', *args, **kwargs):
 
     Return
     ------
-    environment: dict
+    dict
+        environment
     """
-    # Try to get environement from vcvarsall.bat (Classical way)
+    # Try to get environment from vcvarsall.bat (Classical way)
     try:
         orig = get_unpatched(msvc9_query_vcvarsall)
         return orig(ver, arch, *args, **kwargs)
@@ -153,17 +145,10 @@ def msvc9_query_vcvarsall(ver, arch='x86', *args, **kwargs):
 def msvc14_get_vc_env(plat_spec):
     """
     Patched "distutils._msvccompiler._get_vc_env" for support extra
-    compilers.
+    Microsoft Visual C++ 14.X compilers.
 
     Set environment without use of "vcvarsall.bat".
 
-    Known supported compilers
-    -------------------------
-    Microsoft Visual C++ 14.0:
-        Microsoft Visual C++ Build Tools 2015 (x86, x64, arm)
-        Microsoft Visual Studio 2017 (x86, x64, arm, arm64)
-        Microsoft Visual Studio Build Tools 2017 (x86, x64, arm, arm64)
-
     Parameters
     ----------
     plat_spec: str
@@ -171,7 +156,8 @@ def msvc14_get_vc_env(plat_spec):
 
     Return
     ------
-    environment: dict
+    dict
+        environment
     """
     # Try to get environment from vcvarsall.bat (Classical way)
     try:
@@ -217,9 +203,9 @@ def _augment_exception(exc, version, arch=''):
         if version == 9.0:
             if arch.lower().find('ia64') > -1:
                 # For VC++ 9.0, if IA64 support is needed, redirect user
-                # to Windows SDK 7.0
-                message += ' Get it with "Microsoft Windows SDK 7.0": '
-                message += msdownload % 3138
+                # to Windows SDK 7.0.
+                # Note: No download link available from Microsoft.
+                message += ' Get it with "Microsoft Windows SDK 7.0"'
             else:
                 # For VC++ 9.0 redirect user to Vc++ for Python 2.7 :
                 # This redirection link is maintained by Microsoft.
@@ -230,8 +216,8 @@ def _augment_exception(exc, version, arch=''):
             message += ' Get it with "Microsoft Windows SDK 7.1": '
             message += msdownload % 8279
         elif version >= 14.0:
-            # For VC++ 14.0 Redirect user to Visual C++ Build Tools
-            message += (' Get it with "Microsoft Visual C++ Build Tools": '
+            # For VC++ 14.X Redirect user to latest Visual C++ Build Tools
+            message += (' Get it with "Build Tools for Visual Studio": '
                         r'https://visualstudio.microsoft.com/downloads/')
 
     exc.args = (message, )
@@ -239,26 +225,50 @@ def _augment_exception(exc, version, arch=''):
 
 class PlatformInfo:
     """
-    Current and Target Architectures informations.
+    Current and Target Architectures information.
 
     Parameters
     ----------
     arch: str
         Target architecture.
     """
-    current_cpu = safe_env.get('processor_architecture', '').lower()
+    current_cpu = environ.get('processor_architecture', '').lower()
 
     def __init__(self, arch):
         self.arch = arch.lower().replace('x64', 'amd64')
 
     @property
     def target_cpu(self):
+        """
+        Return Target CPU architecture.
+
+        Return
+        ------
+        str
+            Target CPU
+        """
         return self.arch[self.arch.find('_') + 1:]
 
     def target_is_x86(self):
+        """
+        Return True if target CPU is x86 32 bits..
+
+        Return
+        ------
+        bool
+            CPU is x86 32 bits
+        """
         return self.target_cpu == 'x86'
 
     def current_is_x86(self):
+        """
+        Return True if current CPU is x86 32 bits..
+
+        Return
+        ------
+        bool
+            CPU is x86 32 bits
+        """
         return self.current_cpu == 'x86'
 
     def current_dir(self, hidex86=False, x64=False):
@@ -274,8 +284,8 @@ class PlatformInfo:
 
         Return
         ------
-        subfolder: str
-            '\target', or '' (see hidex86 parameter)
+        str
+            subfolder: '\target', or '' (see hidex86 parameter)
         """
         return (
             '' if (self.current_cpu == 'x86' and hidex86) else
@@ -296,8 +306,8 @@ class PlatformInfo:
 
         Return
         ------
-        subfolder: str
-            '\current', or '' (see hidex86 parameter)
+        str
+            subfolder: '\current', or '' (see hidex86 parameter)
         """
         return (
             '' if (self.target_cpu == 'x86' and hidex86) else
@@ -312,13 +322,13 @@ class PlatformInfo:
         Parameters
         ----------
         forcex86: bool
-            Use 'x86' as current architecture even if current acritecture is
+            Use 'x86' as current architecture even if current architecture is
             not x86.
 
         Return
         ------
-        subfolder: str
-            '' if target architecture is current architecture,
+        str
+            subfolder: '' if target architecture is current architecture,
             '\current_target' if not.
         """
         current = 'x86' if forcex86 else self.current_cpu
@@ -330,7 +340,7 @@ class PlatformInfo:
 
 class RegistryInfo:
     """
-    Microsoft Visual Studio related registry informations.
+    Microsoft Visual Studio related registry information.
 
     Parameters
     ----------
@@ -349,6 +359,11 @@ class RegistryInfo:
     def visualstudio(self):
         """
         Microsoft Visual Studio root registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
         return 'VisualStudio'
 
@@ -356,27 +371,47 @@ class RegistryInfo:
     def sxs(self):
         """
         Microsoft Visual Studio SxS registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
-        return os.path.join(self.visualstudio, 'SxS')
+        return join(self.visualstudio, 'SxS')
 
     @property
     def vc(self):
         """
         Microsoft Visual C++ VC7 registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
-        return os.path.join(self.sxs, 'VC7')
+        return join(self.sxs, 'VC7')
 
     @property
     def vs(self):
         """
         Microsoft Visual Studio VS7 registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
-        return os.path.join(self.sxs, 'VS7')
+        return join(self.sxs, 'VS7')
 
     @property
     def vc_for_python(self):
         """
         Microsoft Visual C++ for Python registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
         return r'DevDiv\VCForPython'
 
@@ -384,6 +419,11 @@ class RegistryInfo:
     def microsoft_sdk(self):
         """
         Microsoft SDK registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
         return 'Microsoft SDKs'
 
@@ -391,20 +431,35 @@ class RegistryInfo:
     def windows_sdk(self):
         """
         Microsoft Windows/Platform SDK registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
-        return os.path.join(self.microsoft_sdk, 'Windows')
+        return join(self.microsoft_sdk, 'Windows')
 
     @property
     def netfx_sdk(self):
         """
         Microsoft .NET Framework SDK registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
-        return os.path.join(self.microsoft_sdk, 'NETFXSDK')
+        return join(self.microsoft_sdk, 'NETFXSDK')
 
     @property
     def windows_kits_roots(self):
         """
         Microsoft Windows Kits Roots registry key.
+
+        Return
+        ------
+        str
+            Registry key
         """
         return r'Windows Kits\Installed Roots'
 
@@ -421,10 +476,11 @@ class RegistryInfo:
 
         Return
         ------
-        str: value
+        str
+            Registry key
         """
         node64 = '' if self.pi.current_is_x86() or x86 else 'Wow6432Node'
-        return os.path.join('Software', node64, 'Microsoft', key)
+        return join('Software', node64, 'Microsoft', key)
 
     def lookup(self, key, name):
         """
@@ -439,18 +495,19 @@ class RegistryInfo:
 
         Return
         ------
-        str: value
+        str
+            value
         """
-        KEY_READ = winreg.KEY_READ
+        key_read = winreg.KEY_READ
         openkey = winreg.OpenKey
         ms = self.microsoft
         for hkey in self.HKEYS:
             try:
-                bkey = openkey(hkey, ms(key), 0, KEY_READ)
+                bkey = openkey(hkey, ms(key), 0, key_read)
             except (OSError, IOError):
                 if not self.pi.current_is_x86():
                     try:
-                        bkey = openkey(hkey, ms(key, True), 0, KEY_READ)
+                        bkey = openkey(hkey, ms(key, True), 0, key_read)
                     except (OSError, IOError):
                         continue
                 else:
@@ -463,7 +520,7 @@ class RegistryInfo:
 
 class SystemInfo:
     """
-    Microsoft Windows and Visual Studio related system inormations.
+    Microsoft Windows and Visual Studio related system information.
 
     Parameters
     ----------
@@ -474,30 +531,52 @@ class SystemInfo:
     """
 
     # Variables and properties in this class use originals CamelCase variables
-    # names from Microsoft source files for more easy comparaison.
-    WinDir = safe_env.get('WinDir', '')
-    ProgramFiles = safe_env.get('ProgramFiles', '')
-    ProgramFilesx86 = safe_env.get('ProgramFiles(x86)', ProgramFiles)
+    # names from Microsoft source files for more easy comparison.
+    WinDir = environ.get('WinDir', '')
+    ProgramFiles = environ.get('ProgramFiles', '')
+    ProgramFilesx86 = environ.get('ProgramFiles(x86)', ProgramFiles)
 
     def __init__(self, registry_info, vc_ver=None):
         self.ri = registry_info
         self.pi = self.ri.pi
-        self.vc_ver = vc_ver or self._find_latest_available_vc_ver()
 
-    def _find_latest_available_vc_ver(self):
-        try:
-            return self.find_available_vc_vers()[-1]
-        except IndexError:
-            err = 'No Microsoft Visual C++ version found'
-            raise distutils.errors.DistutilsPlatformError(err)
+        self.known_vs_paths = self.find_programdata_vs_vers()
+
+        # Except for VS15+, VC version is aligned with VS version
+        self.vs_ver = self.vc_ver = (
+                vc_ver or self._find_latest_available_vs_ver())
+
+    def _find_latest_available_vs_ver(self):
+        """
+        Find the latest VC version
+
+        Return
+        ------
+        float
+            version
+        """
+        reg_vc_vers = self.find_reg_vs_vers()
+
+        if not (reg_vc_vers or self.known_vs_paths):
+            raise distutils.errors.DistutilsPlatformError(
+                'No Microsoft Visual C++ version found')
+
+        vc_vers = set(reg_vc_vers)
+        vc_vers.update(self.known_vs_paths)
+        return sorted(vc_vers)[-1]
 
-    def find_available_vc_vers(self):
+    def find_reg_vs_vers(self):
         """
-        Find all available Microsoft Visual C++ versions.
+        Find Microsoft Visual Studio versions available in registry.
+
+        Return
+        ------
+        list of float
+            Versions
         """
         ms = self.ri.microsoft
         vckeys = (self.ri.vc, self.ri.vc_for_python, self.ri.vs)
-        vc_vers = []
+        vs_vers = []
         for hkey in self.ri.HKEYS:
             for key in vckeys:
                 try:
@@ -508,49 +587,108 @@ class SystemInfo:
                 for i in range(values):
                     try:
                         ver = float(winreg.EnumValue(bkey, i)[0])
-                        if ver not in vc_vers:
-                            vc_vers.append(ver)
+                        if ver not in vs_vers:
+                            vs_vers.append(ver)
                     except ValueError:
                         pass
                 for i in range(subkeys):
                     try:
                         ver = float(winreg.EnumKey(bkey, i))
-                        if ver not in vc_vers:
-                            vc_vers.append(ver)
+                        if ver not in vs_vers:
+                            vs_vers.append(ver)
                     except ValueError:
                         pass
-        return sorted(vc_vers)
+        return sorted(vs_vers)
+
+    def find_programdata_vs_vers(self):
+        r"""
+        Find Visual studio 2017+ versions from information in
+        "C:\ProgramData\Microsoft\VisualStudio\Packages\_Instances".
+
+        Return
+        ------
+        dict
+            float version as key, path as value.
+        """
+        vs_versions = {}
+        instances_dir = \
+            r'C:\ProgramData\Microsoft\VisualStudio\Packages\_Instances'
+
+        try:
+            hashed_names = listdir(instances_dir)
+
+        except (OSError, IOError):
+            # Directory not exists with all Visual Studio versions
+            return vs_versions
+
+        for name in hashed_names:
+            try:
+                # Get VS installation path from "state.json" file
+                state_path = join(instances_dir, name, 'state.json')
+                with open(state_path, 'rt', encoding='utf-8') as state_file:
+                    state = json.load(state_file)
+                vs_path = state['installationPath']
+
+                # Raises OSError if this VS installation does not contain VC
+                listdir(join(vs_path, r'VC\Tools\MSVC'))
+
+                # Store version and path
+                vs_versions[self._as_float_version(
+                    state['installationVersion'])] = vs_path
+
+            except (OSError, IOError, KeyError):
+                # Skip if "state.json" file is missing or bad format
+                continue
+
+        return vs_versions
+
+    @staticmethod
+    def _as_float_version(version):
+        """
+        Return a string version as a simplified float version (major.minor)
+
+        Parameters
+        ----------
+        version: str
+            Version.
+
+        Return
+        ------
+        float
+            version
+        """
+        return float('.'.join(version.split('.')[:2]))
 
     @property
     def VSInstallDir(self):
         """
         Microsoft Visual Studio directory.
+
+        Return
+        ------
+        str
+            path
         """
         # Default path
-        name = 'Microsoft Visual Studio %0.1f' % self.vc_ver
-        default = os.path.join(self.ProgramFilesx86, name)
+        default = join(self.ProgramFilesx86,
+                       'Microsoft Visual Studio %0.1f' % self.vs_ver)
 
         # Try to get path from registry, if fail use default path
-        return self.ri.lookup(self.ri.vs, '%0.1f' % self.vc_ver) or default
+        return self.ri.lookup(self.ri.vs, '%0.1f' % self.vs_ver) or default
 
     @property
     def VCInstallDir(self):
         """
         Microsoft Visual C++ directory.
-        """
-        self.VSInstallDir
-
-        guess_vc = self._guess_vc() or self._guess_vc_legacy()
-
-        # Try to get "VC++ for Python" path from registry as default path
-        reg_path = os.path.join(self.ri.vc_for_python, '%0.1f' % self.vc_ver)
-        python_vc = self.ri.lookup(reg_path, 'installdir')
-        default_vc = os.path.join(python_vc, 'VC') if python_vc else guess_vc
 
-        # Try to get path from registry, if fail use default path
-        path = self.ri.lookup(self.ri.vc, '%0.1f' % self.vc_ver) or default_vc
+        Return
+        ------
+        str
+            path
+        """
+        path = self._guess_vc() or self._guess_vc_legacy()
 
-        if not os.path.isdir(path):
+        if not isdir(path):
             msg = 'Microsoft Visual C++ directory not found'
             raise distutils.errors.DistutilsPlatformError(msg)
 
@@ -558,186 +696,256 @@ class SystemInfo:
 
     def _guess_vc(self):
         """
-        Locate Visual C for 2017
+        Locate Visual C++ for VS2017+.
+
+        Return
+        ------
+        str
+            path
         """
-        if self.vc_ver <= 14.0:
-            return
+        if self.vs_ver <= 14.0:
+            return ''
+
+        try:
+            # First search in known VS paths
+            vs_dir = self.known_vs_paths[self.vs_ver]
+        except KeyError:
+            # Else, search with path from registry
+            vs_dir = self.VSInstallDir
+
+        guess_vc = join(vs_dir, r'VC\Tools\MSVC')
 
-        default = r'VC\Tools\MSVC'
-        guess_vc = os.path.join(self.VSInstallDir, default)
         # Subdir with VC exact version as name
         try:
-            vc_exact_ver = os.listdir(guess_vc)[-1]
-            return os.path.join(guess_vc, vc_exact_ver)
+            # Update the VC version with real one instead of VS version
+            vc_ver = listdir(guess_vc)[-1]
+            self.vc_ver = self._as_float_version(vc_ver)
+            return join(guess_vc, vc_ver)
         except (OSError, IOError, IndexError):
-            pass
+            return ''
 
     def _guess_vc_legacy(self):
         """
-        Locate Visual C for versions prior to 2017
+        Locate Visual C++ for versions prior to 2017.
+
+        Return
+        ------
+        str
+            path
         """
-        default = r'Microsoft Visual Studio %0.1f\VC' % self.vc_ver
-        return os.path.join(self.ProgramFilesx86, default)
+        default = join(self.ProgramFilesx86,
+                       r'Microsoft Visual Studio %0.1f\VC' % self.vs_ver)
+
+        # Try to get "VC++ for Python" path from registry as default path
+        reg_path = join(self.ri.vc_for_python, '%0.1f' % self.vs_ver)
+        python_vc = self.ri.lookup(reg_path, 'installdir')
+        default_vc = join(python_vc, 'VC') if python_vc else default
+
+        # Try to get path from registry, if fail use default path
+        return self.ri.lookup(self.ri.vc, '%0.1f' % self.vs_ver) or default_vc
 
     @property
     def WindowsSdkVersion(self):
         """
         Microsoft Windows SDK versions for specified MSVC++ version.
-        """
-        if self.vc_ver <= 9.0:
-            return ('7.0', '6.1', '6.0a')
-        elif self.vc_ver == 10.0:
-            return ('7.1', '7.0a')
-        elif self.vc_ver == 11.0:
-            return ('8.0', '8.0a')
-        elif self.vc_ver == 12.0:
-            return ('8.1', '8.1a')
-        elif self.vc_ver >= 14.0:
-            return ('10.0', '8.1')
+
+        Return
+        ------
+        tuple of str
+            versions
+        """
+        if self.vs_ver <= 9.0:
+            return '7.0', '6.1', '6.0a'
+        elif self.vs_ver == 10.0:
+            return '7.1', '7.0a'
+        elif self.vs_ver == 11.0:
+            return '8.0', '8.0a'
+        elif self.vs_ver == 12.0:
+            return '8.1', '8.1a'
+        elif self.vs_ver >= 14.0:
+            return '10.0', '8.1'
 
     @property
     def WindowsSdkLastVersion(self):
         """
-        Microsoft Windows SDK last version
+        Microsoft Windows SDK last version.
+
+        Return
+        ------
+        str
+            version
         """
-        return self._use_last_dir_name(os.path.join(
-            self.WindowsSdkDir, 'lib'))
+        return self._use_last_dir_name(join(self.WindowsSdkDir, 'lib'))
 
     @property
     def WindowsSdkDir(self):
         """
         Microsoft Windows SDK directory.
+
+        Return
+        ------
+        str
+            path
         """
         sdkdir = ''
         for ver in self.WindowsSdkVersion:
             # Try to get it from registry
-            loc = os.path.join(self.ri.windows_sdk, 'v%s' % ver)
+            loc = join(self.ri.windows_sdk, 'v%s' % ver)
             sdkdir = self.ri.lookup(loc, 'installationfolder')
             if sdkdir:
                 break
-        if not sdkdir or not os.path.isdir(sdkdir):
+        if not sdkdir or not isdir(sdkdir):
             # Try to get "VC++ for Python" version from registry
-            path = os.path.join(self.ri.vc_for_python, '%0.1f' % self.vc_ver)
+            path = join(self.ri.vc_for_python, '%0.1f' % self.vc_ver)
             install_base = self.ri.lookup(path, 'installdir')
             if install_base:
-                sdkdir = os.path.join(install_base, 'WinSDK')
-        if not sdkdir or not os.path.isdir(sdkdir):
+                sdkdir = join(install_base, 'WinSDK')
+        if not sdkdir or not isdir(sdkdir):
             # If fail, use default new path
             for ver in self.WindowsSdkVersion:
                 intver = ver[:ver.rfind('.')]
-                path = r'Microsoft SDKs\Windows Kits\%s' % (intver)
-                d = os.path.join(self.ProgramFiles, path)
-                if os.path.isdir(d):
+                path = r'Microsoft SDKs\Windows Kits\%s' % intver
+                d = join(self.ProgramFiles, path)
+                if isdir(d):
                     sdkdir = d
-        if not sdkdir or not os.path.isdir(sdkdir):
+        if not sdkdir or not isdir(sdkdir):
             # If fail, use default old path
             for ver in self.WindowsSdkVersion:
                 path = r'Microsoft SDKs\Windows\v%s' % ver
-                d = os.path.join(self.ProgramFiles, path)
-                if os.path.isdir(d):
+                d = join(self.ProgramFiles, path)
+                if isdir(d):
                     sdkdir = d
         if not sdkdir:
             # If fail, use Platform SDK
-            sdkdir = os.path.join(self.VCInstallDir, 'PlatformSDK')
+            sdkdir = join(self.VCInstallDir, 'PlatformSDK')
         return sdkdir
 
     @property
     def WindowsSDKExecutablePath(self):
         """
         Microsoft Windows SDK executable directory.
+
+        Return
+        ------
+        str
+            path
         """
         # Find WinSDK NetFx Tools registry dir name
-        if self.vc_ver <= 11.0:
+        if self.vs_ver <= 11.0:
             netfxver = 35
             arch = ''
         else:
             netfxver = 40
-            hidex86 = True if self.vc_ver <= 12.0 else False
+            hidex86 = True if self.vs_ver <= 12.0 else False
             arch = self.pi.current_dir(x64=True, hidex86=hidex86)
         fx = 'WinSDK-NetFx%dTools%s' % (netfxver, arch.replace('\\', '-'))
 
-        # liste all possibles registry paths
+        # list all possibles registry paths
         regpaths = []
-        if self.vc_ver >= 14.0:
+        if self.vs_ver >= 14.0:
             for ver in self.NetFxSdkVersion:
-                regpaths += [os.path.join(self.ri.netfx_sdk, ver, fx)]
+                regpaths += [join(self.ri.netfx_sdk, ver, fx)]
 
         for ver in self.WindowsSdkVersion:
-            regpaths += [os.path.join(self.ri.windows_sdk, 'v%sA' % ver, fx)]
+            regpaths += [join(self.ri.windows_sdk, 'v%sA' % ver, fx)]
 
         # Return installation folder from the more recent path
         for path in regpaths:
             execpath = self.ri.lookup(path, 'installationfolder')
             if execpath:
-                break
-        return execpath
+                return execpath
 
     @property
     def FSharpInstallDir(self):
         """
         Microsoft Visual F# directory.
+
+        Return
+        ------
+        str
+            path
         """
-        path = r'%0.1f\Setup\F#' % self.vc_ver
-        path = os.path.join(self.ri.visualstudio, path)
+        path = join(self.ri.visualstudio, r'%0.1f\Setup\F#' % self.vs_ver)
         return self.ri.lookup(path, 'productdir') or ''
 
     @property
     def UniversalCRTSdkDir(self):
         """
         Microsoft Universal CRT SDK directory.
+
+        Return
+        ------
+        str
+            path
         """
         # Set Kit Roots versions for specified MSVC++ version
-        if self.vc_ver >= 14.0:
-            vers = ('10', '81')
-        else:
-            vers = ()
+        vers = ('10', '81') if self.vs_ver >= 14.0 else ()
 
         # Find path of the more recent Kit
         for ver in vers:
             sdkdir = self.ri.lookup(self.ri.windows_kits_roots,
                                     'kitsroot%s' % ver)
             if sdkdir:
-                break
-        return sdkdir or ''
+                return sdkdir or ''
 
     @property
     def UniversalCRTSdkLastVersion(self):
         """
-        Microsoft Universal C Runtime SDK last version
+        Microsoft Universal C Runtime SDK last version.
+
+        Return
+        ------
+        str
+            version
         """
-        return self._use_last_dir_name(os.path.join(
-            self.UniversalCRTSdkDir, 'lib'))
+        return self._use_last_dir_name(join(self.UniversalCRTSdkDir, 'lib'))
 
     @property
     def NetFxSdkVersion(self):
         """
         Microsoft .NET Framework SDK versions.
+
+        Return
+        ------
+        tuple of str
+            versions
         """
-        # Set FxSdk versions for specified MSVC++ version
-        if self.vc_ver >= 14.0:
-            return ('4.6.1', '4.6')
-        else:
-            return ()
+        # Set FxSdk versions for specified VS version
+        return (('4.7.2', '4.7.1', '4.7',
+                 '4.6.2', '4.6.1', '4.6',
+                 '4.5.2', '4.5.1', '4.5')
+                if self.vs_ver >= 14.0 else ())
 
     @property
     def NetFxSdkDir(self):
         """
         Microsoft .NET Framework SDK directory.
+
+        Return
+        ------
+        str
+            path
         """
+        sdkdir = ''
         for ver in self.NetFxSdkVersion:
-            loc = os.path.join(self.ri.netfx_sdk, ver)
+            loc = join(self.ri.netfx_sdk, ver)
             sdkdir = self.ri.lookup(loc, 'kitsinstallationfolder')
             if sdkdir:
                 break
-        return sdkdir or ''
+        return sdkdir
 
     @property
     def FrameworkDir32(self):
         """
         Microsoft .NET Framework 32bit directory.
+
+        Return
+        ------
+        str
+            path
         """
         # Default path
-        guess_fw = os.path.join(self.WinDir, r'Microsoft.NET\Framework')
+        guess_fw = join(self.WinDir, r'Microsoft.NET\Framework')
 
         # Try to get path from registry, if fail use default path
         return self.ri.lookup(self.ri.vc, 'frameworkdir32') or guess_fw
@@ -746,9 +954,14 @@ class SystemInfo:
     def FrameworkDir64(self):
         """
         Microsoft .NET Framework 64bit directory.
+
+        Return
+        ------
+        str
+            path
         """
         # Default path
-        guess_fw = os.path.join(self.WinDir, r'Microsoft.NET\Framework64')
+        guess_fw = join(self.WinDir, r'Microsoft.NET\Framework64')
 
         # Try to get path from registry, if fail use default path
         return self.ri.lookup(self.ri.vc, 'frameworkdir64') or guess_fw
@@ -757,6 +970,11 @@ class SystemInfo:
     def FrameworkVersion32(self):
         """
         Microsoft .NET Framework 32bit versions.
+
+        Return
+        ------
+        tuple of str
+            versions
         """
         return self._find_dot_net_versions(32)
 
@@ -764,6 +982,11 @@ class SystemInfo:
     def FrameworkVersion64(self):
         """
         Microsoft .NET Framework 64bit versions.
+
+        Return
+        ------
+        tuple of str
+            versions
         """
         return self._find_dot_net_versions(64)
 
@@ -775,6 +998,11 @@ class SystemInfo:
         ----------
         bits: int
             Platform number of bits: 32 or 64.
+
+        Return
+        ------
+        tuple of str
+            versions
         """
         # Find actual .NET version in registry
         reg_ver = self.ri.lookup(self.ri.vc, 'frameworkver%d' % bits)
@@ -782,18 +1010,17 @@ class SystemInfo:
         ver = reg_ver or self._use_last_dir_name(dot_net_dir, 'v') or ''
 
         # Set .NET versions for specified MSVC++ version
-        if self.vc_ver >= 12.0:
-            frameworkver = (ver, 'v4.0')
-        elif self.vc_ver >= 10.0:
-            frameworkver = ('v4.0.30319' if ver.lower()[:2] != 'v4' else ver,
-                            'v3.5')
-        elif self.vc_ver == 9.0:
-            frameworkver = ('v3.5', 'v2.0.50727')
-        if self.vc_ver == 8.0:
-            frameworkver = ('v3.0', 'v2.0.50727')
-        return frameworkver
-
-    def _use_last_dir_name(self, path, prefix=''):
+        if self.vs_ver >= 12.0:
+            return ver, 'v4.0'
+        elif self.vs_ver >= 10.0:
+            return 'v4.0.30319' if ver.lower()[:2] != 'v4' else ver, 'v3.5'
+        elif self.vs_ver == 9.0:
+            return 'v3.5', 'v2.0.50727'
+        elif self.vs_ver == 8.0:
+            return 'v3.0', 'v2.0.50727'
+
+    @staticmethod
+    def _use_last_dir_name(path, prefix=''):
         """
         Return name of the last dir in path or '' if no dir found.
 
@@ -802,12 +1029,17 @@ class SystemInfo:
         path: str
             Use dirs in this path
         prefix: str
-            Use only dirs startings by this prefix
+            Use only dirs starting by this prefix
+
+        Return
+        ------
+        str
+            name
         """
         matching_dirs = (
             dir_name
-            for dir_name in reversed(os.listdir(path))
-            if os.path.isdir(os.path.join(path, dir_name)) and
+            for dir_name in reversed(listdir(path))
+            if isdir(join(path, dir_name)) and
             dir_name.startswith(prefix)
         )
         return next(matching_dirs, None) or ''
@@ -818,7 +1050,7 @@ class EnvironmentInfo:
     Return environment variables for specified Microsoft Visual C++ version
     and platform : Lib, Include, Path and libpath.
 
-    This function is compatible with Microsoft Visual C++ 9.0 to 14.0.
+    This function is compatible with Microsoft Visual C++ 9.0 to 14.X.
 
     Script created by analysing Microsoft environment configuration files like
     "vcvars[...].bat", "SetEnv.Cmd", "vcbuildtools.bat", ...
@@ -835,7 +1067,7 @@ class EnvironmentInfo:
     """
 
     # Variables and properties in this class use originals CamelCase variables
-    # names from Microsoft source files for more easy comparaison.
+    # names from Microsoft source files for more easy comparison.
 
     def __init__(self, arch, vc_ver=None, vc_min_ver=0):
         self.pi = PlatformInfo(arch)
@@ -847,204 +1079,254 @@ class EnvironmentInfo:
             raise distutils.errors.DistutilsPlatformError(err)
 
     @property
+    def vs_ver(self):
+        """
+        Microsoft Visual Studio.
+
+        Return
+        ------
+        float
+            version
+        """
+        return self.si.vs_ver
+
+    @property
     def vc_ver(self):
         """
         Microsoft Visual C++ version.
+
+        Return
+        ------
+        float
+            version
         """
         return self.si.vc_ver
 
     @property
     def VSTools(self):
         """
-        Microsoft Visual Studio Tools
+        Microsoft Visual Studio Tools.
+
+        Return
+        ------
+        list of str
+            paths
         """
         paths = [r'Common7\IDE', r'Common7\Tools']
 
-        if self.vc_ver >= 14.0:
+        if self.vs_ver >= 14.0:
             arch_subdir = self.pi.current_dir(hidex86=True, x64=True)
             paths += [r'Common7\IDE\CommonExtensions\Microsoft\TestWindow']
             paths += [r'Team Tools\Performance Tools']
             paths += [r'Team Tools\Performance Tools%s' % arch_subdir]
 
-        return [os.path.join(self.si.VSInstallDir, path) for path in paths]
+        return [join(self.si.VSInstallDir, path) for path in paths]
 
     @property
     def VCIncludes(self):
         """
-        Microsoft Visual C++ & Microsoft Foundation Class Includes
+        Microsoft Visual C++ & Microsoft Foundation Class Includes.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        return [os.path.join(self.si.VCInstallDir, 'Include'),
-                os.path.join(self.si.VCInstallDir, r'ATLMFC\Include')]
+        return [join(self.si.VCInstallDir, 'Include'),
+                join(self.si.VCInstallDir, r'ATLMFC\Include')]
 
     @property
     def VCLibraries(self):
         """
-        Microsoft Visual C++ & Microsoft Foundation Class Libraries
+        Microsoft Visual C++ & Microsoft Foundation Class Libraries.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver >= 15.0:
+        if self.vs_ver >= 15.0:
             arch_subdir = self.pi.target_dir(x64=True)
         else:
             arch_subdir = self.pi.target_dir(hidex86=True)
         paths = ['Lib%s' % arch_subdir, r'ATLMFC\Lib%s' % arch_subdir]
 
-        if self.vc_ver >= 14.0:
+        if self.vs_ver >= 14.0:
             paths += [r'Lib\store%s' % arch_subdir]
 
-        return [os.path.join(self.si.VCInstallDir, path) for path in paths]
+        return [join(self.si.VCInstallDir, path) for path in paths]
 
     @property
     def VCStoreRefs(self):
         """
-        Microsoft Visual C++ store references Libraries
+        Microsoft Visual C++ store references Libraries.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 14.0:
+        if self.vs_ver < 14.0:
             return []
-        return [os.path.join(self.si.VCInstallDir, r'Lib\store\references')]
+        return [join(self.si.VCInstallDir, r'Lib\store\references')]
 
     @property
     def VCTools(self):
         """
-        Microsoft Visual C++ Tools
+        Microsoft Visual C++ Tools.
+
+        Return
+        ------
+        list of str
+            paths
         """
         si = self.si
-        tools = [os.path.join(si.VCInstallDir, 'VCPackages')]
+        tools = [join(si.VCInstallDir, 'VCPackages')]
 
-        forcex86 = True if self.vc_ver <= 10.0 else False
+        forcex86 = True if self.vs_ver <= 10.0 else False
         arch_subdir = self.pi.cross_dir(forcex86)
         if arch_subdir:
-            tools += [os.path.join(si.VCInstallDir, 'Bin%s' % arch_subdir)]
+            tools += [join(si.VCInstallDir, 'Bin%s' % arch_subdir)]
 
-        if self.vc_ver == 14.0:
+        if self.vs_ver == 14.0:
             path = 'Bin%s' % self.pi.current_dir(hidex86=True)
-            tools += [os.path.join(si.VCInstallDir, path)]
+            tools += [join(si.VCInstallDir, path)]
 
-        elif self.vc_ver >= 15.0:
+        elif self.vs_ver >= 15.0:
             host_dir = (r'bin\HostX86%s' if self.pi.current_is_x86() else
                         r'bin\HostX64%s')
-            tools += [os.path.join(
+            tools += [join(
                 si.VCInstallDir, host_dir % self.pi.target_dir(x64=True))]
 
             if self.pi.current_cpu != self.pi.target_cpu:
-                tools += [os.path.join(
+                tools += [join(
                     si.VCInstallDir, host_dir % self.pi.current_dir(x64=True))]
 
         else:
-            tools += [os.path.join(si.VCInstallDir, 'Bin')]
+            tools += [join(si.VCInstallDir, 'Bin')]
 
         return tools
 
     @property
     def OSLibraries(self):
         """
-        Microsoft Windows SDK Libraries
+        Microsoft Windows SDK Libraries.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver <= 10.0:
+        if self.vs_ver <= 10.0:
             arch_subdir = self.pi.target_dir(hidex86=True, x64=True)
-            return [os.path.join(self.si.WindowsSdkDir, 'Lib%s' % arch_subdir)]
+            return [join(self.si.WindowsSdkDir, 'Lib%s' % arch_subdir)]
 
         else:
             arch_subdir = self.pi.target_dir(x64=True)
-            lib = os.path.join(self.si.WindowsSdkDir, 'lib')
+            lib = join(self.si.WindowsSdkDir, 'lib')
             libver = self._sdk_subdir
-            return [os.path.join(lib, '%sum%s' % (libver , arch_subdir))]
+            return [join(lib, '%sum%s' % (libver , arch_subdir))]
 
     @property
     def OSIncludes(self):
         """
-        Microsoft Windows SDK Include
+        Microsoft Windows SDK Include.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        include = os.path.join(self.si.WindowsSdkDir, 'include')
+        include = join(self.si.WindowsSdkDir, 'include')
 
-        if self.vc_ver <= 10.0:
-            return [include, os.path.join(include, 'gl')]
+        if self.vs_ver <= 10.0:
+            return [include, join(include, 'gl')]
 
         else:
-            if self.vc_ver >= 14.0:
+            if self.vs_ver >= 14.0:
                 sdkver = self._sdk_subdir
             else:
                 sdkver = ''
-            return [os.path.join(include, '%sshared' % sdkver),
-                    os.path.join(include, '%sum' % sdkver),
-                    os.path.join(include, '%swinrt' % sdkver)]
+            return [join(include, '%sshared' % sdkver),
+                    join(include, '%sum' % sdkver),
+                    join(include, '%swinrt' % sdkver)]
 
     @property
     def OSLibpath(self):
         """
-        Microsoft Windows SDK Libraries Paths
+        Microsoft Windows SDK Libraries Paths.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        ref = os.path.join(self.si.WindowsSdkDir, 'References')
+        ref = join(self.si.WindowsSdkDir, 'References')
         libpath = []
 
-        if self.vc_ver <= 9.0:
+        if self.vs_ver <= 9.0:
             libpath += self.OSLibraries
 
-        if self.vc_ver >= 11.0:
-            libpath += [os.path.join(ref, r'CommonConfiguration\Neutral')]
+        if self.vs_ver >= 11.0:
+            libpath += [join(ref, r'CommonConfiguration\Neutral')]
 
-        if self.vc_ver >= 14.0:
+        if self.vs_ver >= 14.0:
             libpath += [
                 ref,
-                os.path.join(self.si.WindowsSdkDir, 'UnionMetadata'),
-                os.path.join(
-                    ref,
-                    'Windows.Foundation.UniversalApiContract',
-                    '1.0.0.0',
-                ),
-                os.path.join(
-                    ref,
-                    'Windows.Foundation.FoundationContract',
-                    '1.0.0.0',
-                ),
-                os.path.join(
-                    ref,
-                    'Windows.Networking.Connectivity.WwanContract',
-                    '1.0.0.0',
-                ),
-                os.path.join(
-                    self.si.WindowsSdkDir,
-                    'ExtensionSDKs',
-                    'Microsoft.VCLibs',
-                    '%0.1f' % self.vc_ver,
-                    'References',
-                    'CommonConfiguration',
-                    'neutral',
-                ),
+                join(self.si.WindowsSdkDir, 'UnionMetadata'),
+                join(ref, 'Windows.Foundation.UniversalApiContract', '1.0.0.0'),
+                join(ref, 'Windows.Foundation.FoundationContract', '1.0.0.0'),
+                join(ref,'Windows.Networking.Connectivity.WwanContract',
+                     '1.0.0.0'),
+                join(self.si.WindowsSdkDir, 'ExtensionSDKs', 'Microsoft.VCLibs',
+                     '%0.1f' % self.vs_ver, 'References', 'CommonConfiguration',
+                     'neutral'),
             ]
         return libpath
 
     @property
     def SdkTools(self):
         """
-        Microsoft Windows SDK Tools
+        Microsoft Windows SDK Tools.
+
+        Return
+        ------
+        list of str
+            paths
         """
         return list(self._sdk_tools())
 
     def _sdk_tools(self):
         """
-        Microsoft Windows SDK Tools paths generator
+        Microsoft Windows SDK Tools paths generator.
+
+        Return
+        ------
+        generator of str
+            paths
         """
-        if self.vc_ver < 15.0:
-            bin_dir = 'Bin' if self.vc_ver <= 11.0 else r'Bin\x86'
-            yield os.path.join(self.si.WindowsSdkDir, bin_dir)
+        if self.vs_ver < 15.0:
+            bin_dir = 'Bin' if self.vs_ver <= 11.0 else r'Bin\x86'
+            yield join(self.si.WindowsSdkDir, bin_dir)
 
         if not self.pi.current_is_x86():
             arch_subdir = self.pi.current_dir(x64=True)
             path = 'Bin%s' % arch_subdir
-            yield os.path.join(self.si.WindowsSdkDir, path)
+            yield join(self.si.WindowsSdkDir, path)
 
-        if self.vc_ver == 10.0 or self.vc_ver == 11.0:
+        if self.vs_ver in (10.0, 11.0):
             if self.pi.target_is_x86():
                 arch_subdir = ''
             else:
                 arch_subdir = self.pi.current_dir(hidex86=True, x64=True)
             path = r'Bin\NETFX 4.0 Tools%s' % arch_subdir
-            yield os.path.join(self.si.WindowsSdkDir, path)
+            yield join(self.si.WindowsSdkDir, path)
 
-        elif self.vc_ver >= 15.0:
-            path = os.path.join(self.si.WindowsSdkDir, 'Bin')
+        elif self.vs_ver >= 15.0:
+            path = join(self.si.WindowsSdkDir, 'Bin')
             arch_subdir = self.pi.current_dir(x64=True)
             sdkver = self.si.WindowsSdkLastVersion
-            yield os.path.join(path, '%s%s' % (sdkver, arch_subdir))
+            yield join(path, '%s%s' % (sdkver, arch_subdir))
 
         if self.si.WindowsSDKExecutablePath:
             yield self.si.WindowsSDKExecutablePath
@@ -1052,7 +1334,12 @@ class EnvironmentInfo:
     @property
     def _sdk_subdir(self):
         """
-        Microsoft Windows SDK version subdir
+        Microsoft Windows SDK version subdir.
+
+        Return
+        ------
+        str
+            subdir
         """
         ucrtver = self.si.WindowsSdkLastVersion
         return ('%s\\' % ucrtver) if ucrtver else ''
@@ -1060,22 +1347,32 @@ class EnvironmentInfo:
     @property
     def SdkSetup(self):
         """
-        Microsoft Windows SDK Setup
+        Microsoft Windows SDK Setup.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver > 9.0:
+        if self.vs_ver > 9.0:
             return []
 
-        return [os.path.join(self.si.WindowsSdkDir, 'Setup')]
+        return [join(self.si.WindowsSdkDir, 'Setup')]
 
     @property
     def FxTools(self):
         """
-        Microsoft .NET Framework Tools
+        Microsoft .NET Framework Tools.
+
+        Return
+        ------
+        list of str
+            paths
         """
         pi = self.pi
         si = self.si
 
-        if self.vc_ver <= 10.0:
+        if self.vs_ver <= 10.0:
             include32 = True
             include64 = not pi.target_is_x86() and not pi.current_is_x86()
         else:
@@ -1084,102 +1381,142 @@ class EnvironmentInfo:
 
         tools = []
         if include32:
-            tools += [os.path.join(si.FrameworkDir32, ver)
+            tools += [join(si.FrameworkDir32, ver)
                       for ver in si.FrameworkVersion32]
         if include64:
-            tools += [os.path.join(si.FrameworkDir64, ver)
+            tools += [join(si.FrameworkDir64, ver)
                       for ver in si.FrameworkVersion64]
         return tools
 
     @property
     def NetFxSDKLibraries(self):
         """
-        Microsoft .Net Framework SDK Libraries
+        Microsoft .Net Framework SDK Libraries.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 14.0 or not self.si.NetFxSdkDir:
+        if self.vs_ver < 14.0 or not self.si.NetFxSdkDir:
             return []
 
         arch_subdir = self.pi.target_dir(x64=True)
-        return [os.path.join(self.si.NetFxSdkDir, r'lib\um%s' % arch_subdir)]
+        return [join(self.si.NetFxSdkDir, r'lib\um%s' % arch_subdir)]
 
     @property
     def NetFxSDKIncludes(self):
         """
-        Microsoft .Net Framework SDK Includes
+        Microsoft .Net Framework SDK Includes.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 14.0 or not self.si.NetFxSdkDir:
+        if self.vs_ver < 14.0 or not self.si.NetFxSdkDir:
             return []
 
-        return [os.path.join(self.si.NetFxSdkDir, r'include\um')]
+        return [join(self.si.NetFxSdkDir, r'include\um')]
 
     @property
     def VsTDb(self):
         """
-        Microsoft Visual Studio Team System Database
+        Microsoft Visual Studio Team System Database.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        return [os.path.join(self.si.VSInstallDir, r'VSTSDB\Deploy')]
+        return [join(self.si.VSInstallDir, r'VSTSDB\Deploy')]
 
     @property
     def MSBuild(self):
         """
-        Microsoft Build Engine
+        Microsoft Build Engine.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 12.0:
+        if self.vs_ver < 12.0:
             return []
-        elif self.vc_ver < 15.0:
+        elif self.vs_ver < 15.0:
             base_path = self.si.ProgramFilesx86
             arch_subdir = self.pi.current_dir(hidex86=True)
         else:
             base_path = self.si.VSInstallDir
             arch_subdir = ''
 
-        path = r'MSBuild\%0.1f\bin%s' % (self.vc_ver, arch_subdir)
-        build = [os.path.join(base_path, path)]
+        path = r'MSBuild\%0.1f\bin%s' % (self.vs_ver, arch_subdir)
+        build = [join(base_path, path)]
 
-        if self.vc_ver >= 15.0:
+        if self.vs_ver >= 15.0:
             # Add Roslyn C# & Visual Basic Compiler
-            build += [os.path.join(base_path, path, 'Roslyn')]
+            build += [join(base_path, path, 'Roslyn')]
 
         return build
 
     @property
     def HTMLHelpWorkshop(self):
         """
-        Microsoft HTML Help Workshop
+        Microsoft HTML Help Workshop.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 11.0:
+        if self.vs_ver < 11.0:
             return []
 
-        return [os.path.join(self.si.ProgramFilesx86, 'HTML Help Workshop')]
+        return [join(self.si.ProgramFilesx86, 'HTML Help Workshop')]
 
     @property
     def UCRTLibraries(self):
         """
-        Microsoft Universal C Runtime SDK Libraries
+        Microsoft Universal C Runtime SDK Libraries.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 14.0:
+        if self.vs_ver < 14.0:
             return []
 
         arch_subdir = self.pi.target_dir(x64=True)
-        lib = os.path.join(self.si.UniversalCRTSdkDir, 'lib')
+        lib = join(self.si.UniversalCRTSdkDir, 'lib')
         ucrtver = self._ucrt_subdir
-        return [os.path.join(lib, '%sucrt%s' % (ucrtver, arch_subdir))]
+        return [join(lib, '%sucrt%s' % (ucrtver, arch_subdir))]
 
     @property
     def UCRTIncludes(self):
         """
-        Microsoft Universal C Runtime SDK Include
+        Microsoft Universal C Runtime SDK Include.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 14.0:
+        if self.vs_ver < 14.0:
             return []
 
-        include = os.path.join(self.si.UniversalCRTSdkDir, 'include')
-        return [os.path.join(include, '%sucrt' % self._ucrt_subdir)]
+        include = join(self.si.UniversalCRTSdkDir, 'include')
+        return [join(include, '%sucrt' % self._ucrt_subdir)]
 
     @property
     def _ucrt_subdir(self):
         """
-        Microsoft Universal C Runtime SDK version subdir
+        Microsoft Universal C Runtime SDK version subdir.
+
+        Return
+        ------
+        str
+            subdir
         """
         ucrtver = self.si.UniversalCRTSdkLastVersion
         return ('%s\\' % ucrtver) if ucrtver else ''
@@ -1187,31 +1524,52 @@ class EnvironmentInfo:
     @property
     def FSharp(self):
         """
-        Microsoft Visual F#
+        Microsoft Visual F#.
+
+        Return
+        ------
+        list of str
+            paths
         """
-        if self.vc_ver < 11.0 and self.vc_ver > 12.0:
+        if 11.0 > self.vs_ver > 12.0:
             return []
 
-        return self.si.FSharpInstallDir
+        return [self.si.FSharpInstallDir]
 
     @property
     def VCRuntimeRedist(self):
         """
-        Microsoft Visual C++ runtime redistribuable dll
-        """
-        arch_subdir = self.pi.target_dir(x64=True)
-        if self.vc_ver < 15:
-            redist_path = self.si.VCInstallDir
-            vcruntime = 'redist%s\\Microsoft.VC%d0.CRT\\vcruntime%d0.dll'
-        else:
-            redist_path = self.si.VCInstallDir.replace('\\Tools', '\\Redist')
-            vcruntime = 'onecore%s\\Microsoft.VC%d0.CRT\\vcruntime%d0.dll'
-
-        # Visual Studio 2017  is still Visual C++ 14.0
-        dll_ver = 14.0 if self.vc_ver == 15 else self.vc_ver
+        Microsoft Visual C++ runtime redistributable dll.
 
-        vcruntime = vcruntime % (arch_subdir, self.vc_ver, dll_ver)
-        return os.path.join(redist_path, vcruntime)
+        Return
+        ------
+        str
+            path
+        """
+        vcruntime = 'vcruntime%d0.dll' % self.vc_ver
+        arch_subdir = self.pi.target_dir(x64=True).strip('\\')
+
+        # Installation prefixes candidates
+        prefixes = []
+        tools_path = self.si.VCInstallDir
+        redist_path = dirname(tools_path.replace(r'\Tools', r'\Redist'))
+        if isdir(redist_path):
+            # Redist version may not be exactly the same as tools
+            redist_path = join(redist_path, listdir(redist_path)[-1])
+            prefixes += [redist_path, join(redist_path, 'onecore')]
+
+        prefixes += [join(tools_path, 'redist')]  # VS14 legacy path
+
+        # CRT directory
+        crt_dirs = ('Microsoft.VC%d.CRT' % (self.vc_ver * 10),
+                    # Sometime store in directory with VS version instead of VC
+                    'Microsoft.VC%d.CRT' % (int(self.vs_ver) * 10))
+
+        # vcruntime path
+        for prefix, crt_dir in itertools.product(prefixes, crt_dirs):
+            path = join(prefix, arch_subdir, crt_dir, vcruntime)
+            if isfile(path):
+                return path
 
     def return_env(self, exists=True):
         """
@@ -1221,6 +1579,11 @@ class EnvironmentInfo:
         ----------
         exists: bool
             It True, only return existing paths.
+
+        Return
+        ------
+        dict
+            environment
         """
         env = dict(
             include=self._build_paths('include',
@@ -1254,7 +1617,7 @@ class EnvironmentInfo:
                                     self.FSharp],
                                    exists),
         )
-        if self.vc_ver >= 14 and os.path.isfile(self.VCRuntimeRedist):
+        if self.vs_ver >= 14 and isfile(self.VCRuntimeRedist):
             env['py_vcruntime_redist'] = self.VCRuntimeRedist
         return env
 
@@ -1265,20 +1628,35 @@ class EnvironmentInfo:
         unique, extant, directories from those paths and from
         the environment variable. Raise an error if no paths
         are resolved.
+
+        Parameters
+        ----------
+        name: str
+            Environment variable name
+        spec_path_lists: list of str
+            Paths
+        exists: bool
+            It True, only return existing paths.
+
+        Return
+        ------
+        str
+            Pathsep-separated paths
         """
         # flatten spec_path_lists
         spec_paths = itertools.chain.from_iterable(spec_path_lists)
-        env_paths = safe_env.get(name, '').split(os.pathsep)
+        env_paths = environ.get(name, '').split(pathsep)
         paths = itertools.chain(spec_paths, env_paths)
-        extant_paths = list(filter(os.path.isdir, paths)) if exists else paths
+        extant_paths = list(filter(isdir, paths)) if exists else paths
         if not extant_paths:
             msg = "%s environment variable is empty" % name.upper()
             raise distutils.errors.DistutilsPlatformError(msg)
         unique_paths = self._unique_everseen(extant_paths)
-        return os.pathsep.join(unique_paths)
+        return pathsep.join(unique_paths)
 
     # from Python docs
-    def _unique_everseen(self, iterable, key=None):
+    @staticmethod
+    def _unique_everseen(iterable, key=None):
         """
         List unique elements, preserving order.
         Remember all elements ever seen.
diff --git a/setuptools/package_index.py b/setuptools/package_index.py
index 6b06f2ca..f419d471 100644
--- a/setuptools/package_index.py
+++ b/setuptools/package_index.py
@@ -46,7 +46,7 @@ __all__ = [
 _SOCKET_TIMEOUT = 15
 
 _tmpl = "setuptools/{setuptools.__version__} Python-urllib/{py_major}"
-user_agent = _tmpl.format(py_major=sys.version[:3], setuptools=setuptools)
+user_agent = _tmpl.format(py_major='{}.{}'.format(*sys.version_info), setuptools=setuptools)
 
 
 def parse_requirement_arg(spec):
diff --git a/setuptools/py27compat.py b/setuptools/py27compat.py
index 2985011b..1d57360f 100644
--- a/setuptools/py27compat.py
+++ b/setuptools/py27compat.py
@@ -2,6 +2,7 @@
 Compatibility Support for Python 2.7 and earlier
 """
 
+import sys
 import platform
 
 from setuptools.extern import six
@@ -26,3 +27,34 @@ linux_py2_ascii = (
 
 rmtree_safe = str if linux_py2_ascii else lambda x: x
 """Workaround for http://bugs.python.org/issue24672"""
+
+
+try:
+    from ._imp import find_module, PY_COMPILED, PY_FROZEN, PY_SOURCE
+    from ._imp import get_frozen_object, get_module
+except ImportError:
+    import imp
+    from imp import PY_COMPILED, PY_FROZEN, PY_SOURCE  # noqa
+
+    def find_module(module, paths=None):
+        """Just like 'imp.find_module()', but with package support"""
+        parts = module.split('.')
+        while parts:
+            part = parts.pop(0)
+            f, path, (suffix, mode, kind) = info = imp.find_module(part, paths)
+
+            if kind == imp.PKG_DIRECTORY:
+                parts = parts or ['__init__']
+                paths = [path]
+
+            elif parts:
+                raise ImportError("Can't find %r in %s" % (parts, module))
+
+        return info
+
+    def get_frozen_object(module, paths):
+        return imp.get_frozen_object(module)
+
+    def get_module(module, paths, info):
+        imp.load_module(module, *info)
+        return sys.modules[module]
diff --git a/setuptools/py34compat.py b/setuptools/py34compat.py
new file mode 100644
index 00000000..3ad91722
--- /dev/null
+++ b/setuptools/py34compat.py
@@ -0,0 +1,13 @@
+import importlib
+
+try:
+    import importlib.util
+except ImportError:
+    pass
+
+
+try:
+    module_from_spec = importlib.util.module_from_spec
+except AttributeError:
+    def module_from_spec(spec):
+        return spec.loader.load_module(spec.name)
diff --git a/setuptools/tests/test_bdist_egg.py b/setuptools/tests/test_bdist_egg.py
index 54742aa6..fb5b90b1 100644
--- a/setuptools/tests/test_bdist_egg.py
+++ b/setuptools/tests/test_bdist_egg.py
@@ -42,7 +42,7 @@ class Test:
 
         # let's see if we got our egg link at the right place
         [content] = os.listdir('dist')
-        assert re.match(r'foo-0.0.0-py[23].\d.egg$', content)
+        assert re.match(r'foo-0.0.0-py[23].\d+.egg$', content)
 
     @pytest.mark.xfail(
         os.environ.get('PYTHONDONTWRITEBYTECODE'),
diff --git a/setuptools/tests/test_config.py b/setuptools/tests/test_config.py
index 1b94a586..69d8d00d 100644
--- a/setuptools/tests/test_config.py
+++ b/setuptools/tests/test_config.py
@@ -1,4 +1,4 @@
-# -*- coding: UTF-8 -*-
+# -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
 import contextlib
diff --git a/setuptools/tests/test_integration.py b/setuptools/tests/test_integration.py
index 1c0b2b18..f1a27f8b 100644
--- a/setuptools/tests/test_integration.py
+++ b/setuptools/tests/test_integration.py
@@ -64,7 +64,7 @@ def install_context(request, tmpdir, monkeypatch):
     monkeypatch.setattr('site.USER_BASE', user_base.strpath)
     monkeypatch.setattr('site.USER_SITE', user_site.strpath)
     monkeypatch.setattr('sys.path', sys.path + [install_dir.strpath])
-    monkeypatch.setenv('PYTHONPATH', os.path.pathsep.join(sys.path))
+    monkeypatch.setenv(str('PYTHONPATH'), str(os.path.pathsep.join(sys.path)))
 
     # Set up the command for performing the installation.
     dist = Distribution()
diff --git a/setuptools/tests/test_register.py b/setuptools/tests/test_register.py
index 96114595..98605806 100644
--- a/setuptools/tests/test_register.py
+++ b/setuptools/tests/test_register.py
@@ -1,43 +1,22 @@
-import mock
-from distutils import log
-
-import pytest
-
 from setuptools.command.register import register
 from setuptools.dist import Distribution
+from setuptools.errors import RemovedCommandError
 
+try:
+    from unittest import mock
+except ImportError:
+    import mock
 
-class TestRegisterTest:
-    def test_warns_deprecation(self):
-        dist = Distribution()
-
-        cmd = register(dist)
-        cmd.run_command = mock.Mock()
-        cmd.send_metadata = mock.Mock()
-        cmd.announce = mock.Mock()
-
-        cmd.run()
+import pytest
 
-        cmd.announce.assert_called_with(
-            "WARNING: Registering is deprecated, use twine to upload instead "
-            "(https://pypi.org/p/twine/)",
-            log.WARN
-        )
 
-    def test_warns_deprecation_when_raising(self):
+class TestRegister:
+    def test_register_exception(self):
+        """Ensure that the register command has been properly removed."""
         dist = Distribution()
+        dist.dist_files = [(mock.Mock(), mock.Mock(), mock.Mock())]
 
         cmd = register(dist)
-        cmd.run_command = mock.Mock()
-        cmd.send_metadata = mock.Mock()
-        cmd.send_metadata.side_effect = Exception
-        cmd.announce = mock.Mock()
 
-        with pytest.raises(Exception):
+        with pytest.raises(RemovedCommandError):
             cmd.run()
-
-        cmd.announce.assert_called_with(
-            "WARNING: Registering is deprecated, use twine to upload instead "
-            "(https://pypi.org/p/twine/)",
-            log.WARN
-        )
diff --git a/setuptools/tests/test_test.py b/setuptools/tests/test_test.py
index faaa6ba9..6242a018 100644
--- a/setuptools/tests/test_test.py
+++ b/setuptools/tests/test_test.py
@@ -1,7 +1,8 @@
-# -*- coding: UTF-8 -*-
+# -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
 
+import mock
 from distutils import log
 import os
 
@@ -85,9 +86,7 @@ def test_test(capfd):
     dist.script_name = 'setup.py'
     cmd = test(dist)
     cmd.ensure_finalized()
-    # The test runner calls sys.exit
-    with contexts.suppress_exceptions(SystemExit):
-        cmd.run()
+    cmd.run()
     out, err = capfd.readouterr()
     assert out == 'Foo\n'
 
@@ -119,8 +118,55 @@ def test_tests_are_run_once(capfd):
     dist.script_name = 'setup.py'
     cmd = test(dist)
     cmd.ensure_finalized()
-    # The test runner calls sys.exit
-    with contexts.suppress_exceptions(SystemExit):
-        cmd.run()
+    cmd.run()
     out, err = capfd.readouterr()
     assert out == 'Foo\n'
+
+
+@pytest.mark.usefixtures('sample_test')
+def test_warns_deprecation(capfd):
+    params = dict(
+        name='foo',
+        packages=['name', 'name.space', 'name.space.tests'],
+        namespace_packages=['name'],
+        test_suite='name.space.tests.test_suite',
+        use_2to3=True
+    )
+    dist = Distribution(params)
+    dist.script_name = 'setup.py'
+    cmd = test(dist)
+    cmd.ensure_finalized()
+    cmd.announce = mock.Mock()
+    cmd.run()
+    capfd.readouterr()
+    msg = (
+        "WARNING: Testing via this command is deprecated and will be "
+        "removed in a future version. Users looking for a generic test "
+        "entry point independent of test runner are encouraged to use "
+        "tox."
+    )
+    cmd.announce.assert_any_call(msg, log.WARN)
+
+
+@pytest.mark.usefixtures('sample_test')
+def test_deprecation_stderr(capfd):
+    params = dict(
+        name='foo',
+        packages=['name', 'name.space', 'name.space.tests'],
+        namespace_packages=['name'],
+        test_suite='name.space.tests.test_suite',
+        use_2to3=True
+    )
+    dist = Distribution(params)
+    dist.script_name = 'setup.py'
+    cmd = test(dist)
+    cmd.ensure_finalized()
+    cmd.run()
+    out, err = capfd.readouterr()
+    msg = (
+        "WARNING: Testing via this command is deprecated and will be "
+        "removed in a future version. Users looking for a generic test "
+        "entry point independent of test runner are encouraged to use "
+        "tox.\n"
+    )
+    assert msg in err
diff --git a/setuptools/tests/test_upload.py b/setuptools/tests/test_upload.py
index 320c6959..7586cb26 100644
--- a/setuptools/tests/test_upload.py
+++ b/setuptools/tests/test_upload.py
@@ -1,213 +1,22 @@
-import mock
-import os
-import re
-
-from distutils import log
-from distutils.errors import DistutilsError
-
-import pytest
-
 from setuptools.command.upload import upload
 from setuptools.dist import Distribution
-from setuptools.extern import six
-
-
-def _parse_upload_body(body):
-    boundary = u'\r\n----------------GHSKFJDLGDS7543FJKLFHRE75642756743254'
-    entries = []
-    name_re = re.compile(u'^Content-Disposition: form-data; name="([^\"]+)"')
-
-    for entry in body.split(boundary):
-        pair = entry.split(u'\r\n\r\n')
-        if not len(pair) == 2:
-            continue
-
-        key, value = map(six.text_type.strip, pair)
-        m = name_re.match(key)
-        if m is not None:
-            key = m.group(1)
-
-        entries.append((key, value))
-
-    return entries
-
-
-@pytest.fixture
-def patched_upload(tmpdir):
-    class Fix:
-        def __init__(self, cmd, urlopen):
-            self.cmd = cmd
-            self.urlopen = urlopen
-
-        def __iter__(self):
-            return iter((self.cmd, self.urlopen))
-
-        def get_uploaded_metadata(self):
-            request = self.urlopen.call_args_list[0][0][0]
-            body = request.data.decode('utf-8')
-            entries = dict(_parse_upload_body(body))
-
-            return entries
+from setuptools.errors import RemovedCommandError
 
-    class ResponseMock(mock.Mock):
-        def getheader(self, name, default=None):
-            """Mocked getheader method for response object"""
-            return {
-                'content-type': 'text/plain; charset=utf-8',
-            }.get(name.lower(), default)
+try:
+    from unittest import mock
+except ImportError:
+    import mock
 
-    with mock.patch('setuptools.command.upload.urlopen') as urlopen:
-        urlopen.return_value = ResponseMock()
-        urlopen.return_value.getcode.return_value = 200
-        urlopen.return_value.read.return_value = b''
-
-        content = os.path.join(str(tmpdir), "content_data")
-
-        with open(content, 'w') as f:
-            f.write("Some content")
-
-        dist = Distribution()
-        dist.dist_files = [('sdist', '3.7.0', content)]
-
-        cmd = upload(dist)
-        cmd.announce = mock.Mock()
-        cmd.username = 'user'
-        cmd.password = 'hunter2'
-
-        yield Fix(cmd, urlopen)
-
-
-class TestUploadTest:
-    def test_upload_metadata(self, patched_upload):
-        cmd, patch = patched_upload
-
-        # Set the metadata version to 2.1
-        cmd.distribution.metadata.metadata_version = '2.1'
-
-        # Run the command
-        cmd.ensure_finalized()
-        cmd.run()
-
-        # Make sure we did the upload
-        patch.assert_called_once()
-
-        # Make sure the metadata version is correct in the headers
-        entries = patched_upload.get_uploaded_metadata()
-        assert entries['metadata_version'] == '2.1'
-
-    def test_warns_deprecation(self):
-        dist = Distribution()
-        dist.dist_files = [(mock.Mock(), mock.Mock(), mock.Mock())]
-
-        cmd = upload(dist)
-        cmd.upload_file = mock.Mock()
-        cmd.announce = mock.Mock()
-
-        cmd.run()
+import pytest
 
-        cmd.announce.assert_called_once_with(
-            "WARNING: Uploading via this command is deprecated, use twine to "
-            "upload instead (https://pypi.org/p/twine/)",
-            log.WARN
-        )
 
-    def test_warns_deprecation_when_raising(self):
+class TestUpload:
+    def test_upload_exception(self):
+        """Ensure that the register command has been properly removed."""
         dist = Distribution()
         dist.dist_files = [(mock.Mock(), mock.Mock(), mock.Mock())]
 
         cmd = upload(dist)
-        cmd.upload_file = mock.Mock()
-        cmd.upload_file.side_effect = Exception
-        cmd.announce = mock.Mock()
-
-        with pytest.raises(Exception):
-            cmd.run()
-
-        cmd.announce.assert_called_once_with(
-            "WARNING: Uploading via this command is deprecated, use twine to "
-            "upload instead (https://pypi.org/p/twine/)",
-            log.WARN
-        )
-
-    @pytest.mark.parametrize('url', [
-        'https://example.com/a;parameter',    # Has parameters
-        'https://example.com/a?query',        # Has query
-        'https://example.com/a#fragment',     # Has fragment
-        'ftp://example.com',                  # Invalid scheme
-
-    ])
-    def test_upload_file_invalid_url(self, url, patched_upload):
-        patched_upload.urlopen.side_effect = Exception("Should not be reached")
-
-        cmd = patched_upload.cmd
-        cmd.repository = url
-
-        cmd.ensure_finalized()
-        with pytest.raises(AssertionError):
-            cmd.run()
-
-    def test_upload_file_http_error(self, patched_upload):
-        patched_upload.urlopen.side_effect = six.moves.urllib.error.HTTPError(
-            'https://example.com',
-            404,
-            'File not found',
-            None,
-            None
-        )
-
-        cmd = patched_upload.cmd
-        cmd.ensure_finalized()
 
-        with pytest.raises(DistutilsError):
+        with pytest.raises(RemovedCommandError):
             cmd.run()
-
-        cmd.announce.assert_any_call(
-            'Upload failed (404): File not found',
-            log.ERROR)
-
-    def test_upload_file_os_error(self, patched_upload):
-        patched_upload.urlopen.side_effect = OSError("Invalid")
-
-        cmd = patched_upload.cmd
-        cmd.ensure_finalized()
-
-        with pytest.raises(OSError):
-            cmd.run()
-
-        cmd.announce.assert_any_call('Invalid', log.ERROR)
-
-    @mock.patch('setuptools.command.upload.spawn')
-    def test_upload_file_gpg(self, spawn, patched_upload):
-        cmd, urlopen = patched_upload
-
-        cmd.sign = True
-        cmd.identity = "Alice"
-        cmd.dry_run = True
-        content_fname = cmd.distribution.dist_files[0][2]
-        signed_file = content_fname + '.asc'
-
-        with open(signed_file, 'wb') as f:
-            f.write("signed-data".encode('utf-8'))
-
-        cmd.ensure_finalized()
-        cmd.run()
-
-        # Make sure that GPG was called
-        spawn.assert_called_once_with([
-            "gpg", "--detach-sign", "--local-user", "Alice", "-a",
-            content_fname
-        ], dry_run=True)
-
-        # Read the 'signed' data that was transmitted
-        entries = patched_upload.get_uploaded_metadata()
-        assert entries['gpg_signature'] == 'signed-data'
-
-    def test_show_response_no_error(self, patched_upload):
-        # This test is just that show_response doesn't throw an error
-        # It is not really important what the printed response looks like
-        # in a deprecated command, but we don't want to introduce new
-        # errors when importing this function from distutils
-
-        patched_upload.cmd.show_response = True
-        patched_upload.cmd.ensure_finalized()
-        patched_upload.cmd.run()
diff --git a/setuptools/tests/test_wheel.py b/setuptools/tests/test_wheel.py
index e85a4a7e..d50816c2 100644
--- a/setuptools/tests/test_wheel.py
+++ b/setuptools/tests/test_wheel.py
@@ -451,6 +451,34 @@ WHEEL_INSTALL_TESTS = (
     ),
 
     dict(
+        id='empty_namespace_package',
+        file_defs={
+            'foobar': {
+                '__init__.py': "__import__('pkg_resources').declare_namespace(__name__)",
+            },
+        },
+        setup_kwargs=dict(
+            namespace_packages=['foobar'],
+            packages=['foobar'],
+        ),
+        install_tree=flatten_tree({
+            'foo-1.0-py{py_version}.egg': [
+                'foo-1.0-py{py_version}-nspkg.pth',
+                {'EGG-INFO': [
+                    'PKG-INFO',
+                    'RECORD',
+                    'WHEEL',
+                    'namespace_packages.txt',
+                    'top_level.txt',
+                ]},
+                {'foobar': [
+                    '__init__.py',
+                ]},
+            ]
+        }),
+    ),
+
+    dict(
         id='data_in_package',
         file_defs={
             'foo': {
diff --git a/setuptools/wheel.py b/setuptools/wheel.py
index e11f0a1d..22eec05e 100644
--- a/setuptools/wheel.py
+++ b/setuptools/wheel.py
@@ -1,6 +1,7 @@
 """Wheels support."""
 
 from distutils.util import get_platform
+from distutils import log
 import email
 import itertools
 import os
@@ -162,11 +163,17 @@ class Wheel:
                 extras_require=extras_require,
             ),
         )
-        write_requirements(
-            setup_dist.get_command_obj('egg_info'),
-            None,
-            os.path.join(egg_info, 'requires.txt'),
-        )
+        # Temporarily disable info traces.
+        log_threshold = log._global_log.threshold
+        log.set_threshold(log.WARN)
+        try:
+            write_requirements(
+                setup_dist.get_command_obj('egg_info'),
+                None,
+                os.path.join(egg_info, 'requires.txt'),
+            )
+        finally:
+            log.set_threshold(log_threshold)
 
     @staticmethod
     def _move_data_entries(destination_eggdir, dist_data):
@@ -206,6 +213,8 @@ class Wheel:
             for mod in namespace_packages:
                 mod_dir = os.path.join(destination_eggdir, *mod.split('.'))
                 mod_init = os.path.join(mod_dir, '__init__.py')
-                if os.path.exists(mod_dir) and not os.path.exists(mod_init):
+                if not os.path.exists(mod_dir):
+                    os.mkdir(mod_dir)
+                if not os.path.exists(mod_init):
                     with open(mod_init, 'w') as fp:
                         fp.write(NAMESPACE_PACKAGE_INIT)
diff --git a/tests/manual_test.py b/tests/manual_test.py
deleted file mode 100644
index 99db4b01..00000000
--- a/tests/manual_test.py
+++ /dev/null
@@ -1,100 +0,0 @@
-#!/usr/bin/env python
-
-import sys
-import os
-import shutil
-import tempfile
-import subprocess
-from distutils.command.install import INSTALL_SCHEMES
-from string import Template
-
-from setuptools.extern.six.moves import urllib
-
-
-def _system_call(*args):
-    assert subprocess.call(args) == 0
-
-
-def tempdir(func):
-    def _tempdir(*args, **kwargs):
-        test_dir = tempfile.mkdtemp()
-        old_dir = os.getcwd()
-        os.chdir(test_dir)
-        try:
-            return func(*args, **kwargs)
-        finally:
-            os.chdir(old_dir)
-            shutil.rmtree(test_dir)
-
-    return _tempdir
-
-
-SIMPLE_BUILDOUT = """\
-[buildout]
-
-parts = eggs
-
-[eggs]
-recipe = zc.recipe.egg
-
-eggs =
-    extensions
-"""
-
-BOOTSTRAP = 'http://downloads.buildout.org/1/bootstrap.py'
-PYVER = sys.version.split()[0][:3]
-
-_VARS = {'base': '.',
-         'py_version_short': PYVER}
-
-scheme = 'nt' if sys.platform == 'win32' else 'unix_prefix'
-PURELIB = INSTALL_SCHEMES[scheme]['purelib']
-
-
-@tempdir
-def test_virtualenv():
-    """virtualenv with setuptools"""
-    purelib = os.path.abspath(Template(PURELIB).substitute(**_VARS))
-    _system_call('virtualenv', '--no-site-packages', '.')
-    _system_call('bin/easy_install', 'setuptools==dev')
-    # linux specific
-    site_pkg = os.listdir(purelib)
-    site_pkg.sort()
-    assert 'setuptools' in site_pkg[0]
-    easy_install = os.path.join(purelib, 'easy-install.pth')
-    with open(easy_install) as f:
-        res = f.read()
-    assert 'setuptools' in res
-
-
-@tempdir
-def test_full():
-    """virtualenv + pip + buildout"""
-    _system_call('virtualenv', '--no-site-packages', '.')
-    _system_call('bin/easy_install', '-q', 'setuptools==dev')
-    _system_call('bin/easy_install', '-qU', 'setuptools==dev')
-    _system_call('bin/easy_install', '-q', 'pip')
-    _system_call('bin/pip', 'install', '-q', 'zc.buildout')
-
-    with open('buildout.cfg', 'w') as f:
-        f.write(SIMPLE_BUILDOUT)
-
-    with open('bootstrap.py', 'w') as f:
-        f.write(urllib.request.urlopen(BOOTSTRAP).read())
-
-    _system_call('bin/python', 'bootstrap.py')
-    _system_call('bin/buildout', '-q')
-    eggs = os.listdir('eggs')
-    eggs.sort()
-    assert len(eggs) == 3
-    assert eggs[1].startswith('setuptools')
-    del eggs[1]
-    assert eggs == [
-        'extensions-0.3-py2.6.egg',
-        'zc.recipe.egg-1.2.2-py2.6.egg',
-    ]
-
-
-if __name__ == '__main__':
-    test_virtualenv()
-    test_full()
diff --git a/tests/requirements.txt b/tests/requirements.txt
index cb3e6726..1f70adee 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -9,4 +9,3 @@ coverage>=4.5.1
 pytest-cov>=2.5.1
 paver; python_version>="3.6"
 futures; python_version=="2.7"
-pip==18.1  # Temporary workaround for #1644.
diff --git a/tools/tox_pip.py b/tools/tox_pip.py
new file mode 100644
index 00000000..5aeca805
--- /dev/null
+++ b/tools/tox_pip.py
@@ -0,0 +1,38 @@
+import os
+import shutil
+import subprocess
+import sys
+from glob import glob
+
+VIRTUAL_ENV = os.environ['VIRTUAL_ENV']
+TOX_PIP_DIR = os.path.join(VIRTUAL_ENV, 'pip')
+
+
+def pip(args):
+    # First things first, get a recent (stable) version of pip.
+    if not os.path.exists(TOX_PIP_DIR):
+        subprocess.check_call([sys.executable, '-m', 'pip',
+                               '--disable-pip-version-check',
+                               'install', '-t', TOX_PIP_DIR,
+                               'pip'])
+        shutil.rmtree(glob(os.path.join(TOX_PIP_DIR, 'pip-*.dist-info'))[0])
+    # And use that version.
+    pypath = os.environ.get('PYTHONPATH')
+    pypath = pypath.split(os.pathsep) if pypath is not None else []
+    pypath.insert(0, TOX_PIP_DIR)
+    os.environ['PYTHONPATH'] = os.pathsep.join(pypath)
+    # Disable PEP 517 support when using editable installs.
+    for n, a in enumerate(args):
+        if not a.startswith('-'):
+            if a in 'install' and '-e' in args[n:]:
+                args.insert(n + 1, '--no-use-pep517')
+            break
+    # Fix call for setuptools editable install.
+    for n, a in enumerate(args):
+        if a == '.':
+            args[n] = os.getcwd()
+    subprocess.check_call([sys.executable, '-m', 'pip'] + args, cwd=TOX_PIP_DIR)
+
+
+if __name__ == '__main__':
+    pip(sys.argv[1:])
diff --git a/tox.ini b/tox.ini
index e0eef95a..5d439cb3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,14 +7,16 @@
 [tox]
 envlist=python
 
+[helpers]
+# Wrapper for calls to pip that make sure the version being used is a
+# up-to-date, and to prevent the current working directory from being
+# added to `sys.path`.
+pip = python {toxinidir}/tools/tox_pip.py
+
 [testenv]
-deps=-rtests/requirements.txt
-# Changed from default (`python -m pip ...`)
-# to prevent the current working directory
-# from being added to `sys.path`.
-install_command=python -c 'import sys; sys.path.remove(""); from pkg_resources import load_entry_point; load_entry_point("pip", "console_scripts", "pip")()' install {opts} {packages}
-# Same as above.
-list_dependencies_command={envbindir}/pip freeze --all
+deps=-r{toxinidir}/tests/requirements.txt
+install_command = {[helpers]pip} install {opts} {packages}
+list_dependencies_command = {[helpers]pip} freeze --all
 setenv=COVERAGE_FILE={toxworkdir}/.coverage.{envname}
 # TODO: The passed environment variables came from copying other tox.ini files
 # These should probably be individually annotated to explain what needs them.