"python -m test --coverage" doesn't work on Windows because the tracer ignores the root directory of Python source code.

The code works on Linux because sys.base_prefix and sys.base_exec_prefix don't point to the Python source code, but to /usr/local.

I'm not sure why sys.base_prefix and sys.base_exec_prefix are ignored.

I added a new test for "-m test --coverage" in test_regrtest, but I skipped the test on Windows.

What version of coverage.py is this?

Changes on ignoredirs:

Changeset 294f8aeb4d4b: "Implemented PEP 405 (Python virtual environments)."

-        tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix, libpath],
-                             trace=0, count=1)
+        tracer = trace.Trace(ignoredirs=[sys.base_prefix, sys.base_exec_prefix,
+                             libpath], trace=0, count=1)


Changeset b43f14c103bb: "#5656: detect correct encoding of files when reporting coverage in trace.py, and ignore files in the temporary direct"

-        import trace
-        tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix],
+        import trace, tempfile
+        tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix,
+                                         tempfile.gettempdir()],

Changeset 308c193f51e3: "adds -T option for code coverage.  The implementation is a fairly simpleminded adaptation of Zope3's test.py -T flag."

+        tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix],
+                             trace=False, count=True)

Ooops, copy/paste failure. The right diff is:

Changeset 294f8aeb4d4b: "Implemented PEP 405 (Python virtual environments)."

-        tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix,
+        tracer = trace.Trace(ignoredirs=[sys.base_prefix, sys.base_exec_prefix,
                                          tempfile.gettempdir()],
                              trace=False, count=True)

Attached patch simply removes the list of ignored directories. It fixes test_regrtest.test_coverage() on Windows.

New changeset 0f10e0b3e76d by Victor Stinner in branch 'default':
Fix regrtest --coverage on Windows
https://hg.python.org/cpython/rev/0f10e0b3e76d

Ok, I fixed the issue by removing the list of ignored directories.

New changeset a5bb62436e25614276ac4b8e252a87f3fcc946cd by Victor Stinner in branch '2.7':
[2.7] bpo-30283: regrtest: backport test_slow_interrupted() and test_coverage() (#1541)
https://github.com/python/cpython/commit/a5bb62436e25614276ac4b8e252a87f3fcc946cd