From 088d090ed3016aca68f3376736bf9f2b18d0fe7e Mon Sep 17 00:00:00 2001 From: Eliah Kagan Date: Thu, 12 Jun 2025 02:39:11 -0400 Subject: [PATCH] Run `cat_file.py` fixture without site customizations This fixes a new `TestGit::test_handle_process_output` test failure on Cygwin where a `CoverageWarning` was printed to stderr in the Python interpreter subprocess running the `cat_file.py` fixture. We usually run the test suite with `pytest-cov` enabled. This is configured in `pyproject.toml` to happen by default. `pytest-cov` uses the `coverage` module, but it adds some more functionality. This includes instrumenting subprocesses, which is achieved by installing its `pytest-cov.pth` file into `site-packages` to be run by all Python interpreter instances. This causes interpeters to check for environment variables such as `COV_CORE_SOURCE` and to conditionally initialize `pytest_cov`. For details, see: https://pytest-cov.readthedocs.io/en/latest/subprocess-support.html `coverage` 7.9.0 was recently released. One of the changes is to start issuing a warning if it can't import the C tracer core. See: https://github.com/nedbat/coveragepy/releases/tag/7.9.0 If this warning is issued in the `cat_file.py` subprocess used in `test_handle_process_output`, it causes the test to fail, because the subprocess writes two more lines to its standard error stream, which cause the line count to come out as two more than expected: /cygdrive/d/a/GitPython/GitPython/.venv/lib/python3.9/site-packages/coverage/core.py:96: CoverageWarning: Couldn't import C tracer: No module named 'coverage.tracer' (no-ctracer) warn(f"Couldn't import C tracer: {IMPORT_ERROR}", slug="no-ctracer", once=True) On most platforms, there is no failure, because the condition the warnings describe does not occur, so there are no warnings. But on Cygwin it does occur, resulting in a new test failure, showing > self.assertEqual(len(actual_lines[2]), expected_line_count, repr(actual_lines[2])) E AssertionError: 5004 != 5002 : ["/cygdrive/d/a/GitPython/GitPython/.venv/lib/python3.9/site-packages/coverage/core.py:96: CoverageWarning: Couldn't import C tracer: No module named 'coverage.tracer' (no-ctracer)\n", ' warn(f"Couldn\'t import C tracer: {IMPORT_ERROR}", slug="no-ctracer", once=True)\n', 'From github.com:jantman/gitpython_issue_301\n', ' = [up to date] master -> origin/master\n', ' = [up to date] testcommit1 -> origin/testcommit1\n', ' = [up to date] testcommit10 -> origin/testcommit10\n', ... where the first two elements of the list are from the lines of the warning message, and the others are as expected. (The above is a highly abridged extract, with the `...` at the end standing for many more list items obtained through the `cat_file.py` fixture.) This new failure is triggered specifically by the new `coverage` package version. It is not due to any recent changes in GitPython. It can be observed by rerunning CI checks that have previously passed, or in: https://github.com/EliahKagan/GitPython/actions/runs/15598239952/job/43940156308#step:14:355 There is more than one possible way to fix this, including fixing the underlying condition being warned about on Cygwin, or sanitizing environment variables for the subprocess. The approach taken here instead is based on the idea that the `cat_file.py` fixture is very simple, and that it is conceptually just a standalone Python script that doesn't do anything meant to depend on the current Python environment. Accordingly, this passes the `-S` option to the interpreter for the `cat_file.py` subprocess, so that interpreter refrains from loading the `site` module. This includes, among other simplifying effects, that the subprocess performs no `.pth` customizations. --- test/test_git.py | 1 + 1 file changed, 1 insertion(+) diff --git a/test/test_git.py b/test/test_git.py index 5bcf89bdd..4a54d0d9b 100644 --- a/test/test_git.py +++ b/test/test_git.py @@ -773,6 +773,7 @@ def stderr_handler(line): cmdline = [ sys.executable, + "-S", # Keep any `CoverageWarning` messages out of the subprocess stderr. fixture_path("cat_file.py"), str(fixture_path("issue-301_stderr")), ]