Correctly track line numbers for multi-line code blocks

Improved the line-number tracking for source lines inside of Python  ``<%
... %>`` blocks, such that text- and HTML-formatted exception traces such
as that of  :func:`.html_error_template` now report the correct source line
inside the block, rather than the first line of the block itself.
Exceptions in ``<%! ... %>`` blocks which get raised while loading the
module are still not reported correctly, as these are handled before the
Mako code is generated.  Pull request courtesy Martin von Gagern.

Closes: #297
Pull-request: https://github.com/sqlalchemy/mako/pull/297
Pull-request-sha: 60ad749604f8de0a9b8133430995045a93d0939c

Change-Id: I2086e4370e8e2db7099de01743840286f0160efc

1 files changed, 48 insertions, 0 deletions

diff --git a/test/test_exceptions.py b/test/test_exceptions.py
index c904d65..46fbcdd 100644
--- a/test/test_exceptions.py
+++ b/test/test_exceptions.py
@@ -383,3 +383,51 @@ ${foobar}
             "local variable 'y' referenced before assignment"
             in html_error
         )
+
+    def test_code_block_line_number(self):
+        l = TemplateLookup()
+        l.put_string(
+            "foo.html",
+            """
+<%
+msg = "Something went wrong."
+raise RuntimeError(msg)  # This is the line.
+%>
+            """,
+        )
+        t = l.get_template("foo.html")
+        try:
+            t.render()
+            assert False
+        except:
+            text_error = exceptions.text_error_template().render_unicode()
+            assert 'File "foo_html", line 4, in render_body' in text_error
+            assert "raise RuntimeError(msg)  # This is the line." in text_error
+        else:
+            assert False
+
+    def test_module_block_line_number(self):
+        l = TemplateLookup()
+        l.put_string(
+            "foo.html",
+            """
+<%!
+def foo():
+    msg = "Something went wrong."
+    raise RuntimeError(msg)  # This is the line.
+%>
+${foo()}
+            """,
+        )
+        t = l.get_template("foo.html")
+        try:
+            t.render()
+            assert False
+        except:
+            text_error = exceptions.text_error_template().render_unicode()
+            sys.stderr.write(text_error)
+            assert 'File "foo_html", line 7, in render_body' in text_error
+            assert 'File "foo_html", line 5, in foo' in text_error
+            assert "raise RuntimeError(msg)  # This is the line." in text_error
+        else:
+            assert False