13403: Disable assertion rewriting for external modules

Author: Tusenka

src/_pytest/assertion/rewrite.py

@@ -216,7 +216,7 @@ def _early_rewrite_bailout(self, name: str, state: AssertionState) -> bool:
             if fnmatch_ex(pat, path):
                 return False
 
-        root_path=os.getcwd()
+        root_path = self._get_root_path()
         if not path.is_relative_to(root_path):
             return True
 
@@ -240,13 +240,25 @@ def _should_rewrite(self, name: str, fn: str, state: AssertionState) -> bool:
         # modules not passed explicitly on the command line are only
         # rewritten if they match the naming convention for test files
         fn_path = PurePath(fn)
+        root_path = self._get_root_path()
+        if not fn_path.is_relative_to(root_path):
+            return False
+
         for pat in self.fnpats:
             if fnmatch_ex(pat, fn_path):
                 state.trace(f"matched test file {fn!r}")
                 return True
 
         return self._is_marked_for_rewrite(name, state)
 
+    @staticmethod
+    def _get_root_path():
+        try:
+            root_path = os.getcwd()
+            return root_path
+        except FileNotFoundError:
+            return os.path.dirname(os.path.abspath(sys.argv[0]))
+
     def _is_marked_for_rewrite(self, name: str, state: AssertionState) -> bool:
         try:
             return self._marked_for_rewrite_cache[name]

testing/test_assertrewrite.py

@@ -22,6 +22,8 @@
 from unittest import mock
 import zipfile
 
+from _pytest.monkeypatch import MonkeyPatch
+
 import _pytest._code
 from _pytest._io.saferepr import DEFAULT_REPR_MAX_SIZE
 from _pytest.assertion import util
@@ -1942,6 +1944,27 @@ def test_simple_failure():
             assert hook.find_spec("file") is not None
             assert self.find_spec_calls == ["file"]
 
+
+    def test_assert_excluded_rootpath(
+        self, pytester: Pytester, hook: AssertionRewritingHook, monkeypatch
+    ) -> None:
+        """
+        If test files contained outside rootdir, then skip them
+        """
+        pytester.makepyfile(
+            **{
+                "file.py": """\
+                    def test_simple_failure():
+                        assert 1 + 1 == 3
+                """
+            }
+        )
+        root_path= "{0}/tests".format(os.getcwd())
+        monkeypatch.setattr("os.getcwd", lambda: root_path)
+        with mock.patch.object(hook, "fnpats", ["*.py"]):
+            assert hook.find_spec("file") is None
+
+
     @pytest.mark.skipif(
         sys.platform.startswith("win32"), reason="cannot remove cwd on Windows"
     )