1 files changed, 61 insertions, 9 deletions
diff --git a/tools/tox_pip.py b/tools/tox_pip.py
index 06655fe4..9fe4f905 100644
--- a/tools/tox_pip.py
+++ b/tools/tox_pip.py
@@ -1,6 +1,7 @@
 import os
 import subprocess
 import sys
+import re
 
 
 def remove_setuptools():
@@ -14,17 +15,68 @@ def remove_setuptools():
     subprocess.check_call(cmd, cwd='.tox')
 
 
-def pip(args):
-    # Honor requires-python when installing test suite dependencies
-    if any('-r' in arg for arg in args):
-        os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = '0'
+def bootstrap():
+    print("Running bootstrap")
+    cmd = [sys.executable, '-m', 'bootstrap']
+    subprocess.check_call(cmd)
 
-    # When installing '.', remove setuptools
-    '.' in args and remove_setuptools()
 
-    cmd = [sys.executable, '-m', 'pip'] + args
-    subprocess.check_call(cmd)
+def is_install_self(args):
+    """
+    Do the args represent an install of .?
+    """
+    def strip_extras(arg):
+        match = re.match(r'(.*)?\[.*\]$', arg)
+        return match.group(1) if match else arg
+
+    return (
+        'install' in args
+        and any(
+            arg in ['.', os.getcwd()]
+            for arg in map(strip_extras, args)
+        )
+    )
+
+
+def pip(*args):
+    cmd = [sys.executable, '-m', 'pip'] + list(args)
+    return subprocess.check_call(cmd)
+
+
+def test_dependencies():
+    from ConfigParser import ConfigParser
+
+    def clean(dep):
+        spec, _, _ = dep.partition('#')
+        return spec.strip()
+
+    parser = ConfigParser()
+    parser.read('setup.cfg')
+    raw = parser.get('options.extras_require', 'tests').split('\n')
+    return filter(None, map(clean, raw))
+
+
+def disable_python_requires():
+    """
+    On Python 2, install the dependencies that are selective
+    on Python version while honoring REQUIRES_PYTHON, then
+    disable REQUIRES_PYTHON so that pip can install this
+    checkout of setuptools.
+    """
+    pip('install', *test_dependencies())
+    os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = 'true'
+
+
+def run(args):
+    os.environ['PIP_USE_PEP517'] = 'true'
+
+    if is_install_self(args):
+        remove_setuptools()
+        bootstrap()
+        sys.version_info > (3,) or disable_python_requires()
+
+    pip(*args)
 
 
 if __name__ == '__main__':
-    pip(sys.argv[1:])
+    run(sys.argv[1:])