.pytest_cache is now automatically ignored by Git

changelog/3286.bugfix.rst

@@ -0,0 +1 @@
+``.pytest_cache`` directory is now automatically ignored by Git. Users who would like to contribute a solution for other SCMs please consult/comment on this issue.

src/_pytest/cacheprovider.py

@@ -115,15 +115,18 @@ class Cache(object):
         else:
             with f:
                 json.dump(value, f, indent=2, sort_keys=True)
-                self._ensure_readme()
+                self._ensure_supporting_files()
-
-    def _ensure_readme(self):
 
+    def _ensure_supporting_files(self):
+        """Create supporting files in the cache dir that are not really part of the cache."""
         if self._cachedir.is_dir():
             readme_path = self._cachedir / "README.md"
             if not readme_path.is_file():
                 readme_path.write_text(README_CONTENT)
 
+            msg = u"# created by pytest automatically, do not change\n*"
+            self._cachedir.joinpath(".gitignore").write_text(msg, encoding="UTF-8")
+
 
 class LFPlugin(object):
     """ Plugin which implements the --lf (run last-failing) option """

testing/test_cacheprovider.py

@@ -884,3 +884,14 @@ class TestReadme(object):
         )
         testdir.runpytest()
         assert self.check_readme(testdir) is True
+
+
+def test_gitignore(testdir):
+    """Ensure we automatically create .gitignore file in the pytest_cache directory (#3286)."""
+    from _pytest.cacheprovider import Cache
+
+    config = testdir.parseconfig()
+    cache = Cache.for_config(config)
+    cache.set("foo", "bar")
+    msg = "# created by pytest automatically, do not change\n*"
+    assert cache._cachedir.joinpath(".gitignore").read_text(encoding="UTF-8") == msg