13403: Disable assertion rewriting for external modules - add test for plugins

Author: Tusenka

src/_pytest/assertion/__init__.py

@@ -120,7 +120,7 @@ def rootpath(self):
             # Fixes for py's trying to os.getcwd() on py34
             # when current working directory doesn't exist (previously triggered via xdist only).
             # Ref: https://github.com/pytest-dev/py/pull/207
-            return os.path.dirname(os.path.abspath(sys.argv[0]))
+            return os.path.abspath(os.sep)
 
 
 def install_importhook(config: Config) -> rewrite.AssertionRewritingHook:

testing/test_assertrewrite.py

@@ -22,6 +22,7 @@
 from typing import cast
 from unittest import mock
 import zipfile
+from mock.mock import Mock
 
 import _pytest._code
 from _pytest._io.saferepr import DEFAULT_REPR_MAX_SIZE
@@ -36,6 +37,7 @@
 from _pytest.assertion.rewrite import rewrite_asserts
 from _pytest.config import Config
 from _pytest.config import ExitCode
+from _pytest.monkeypatch import MonkeyPatch
 from _pytest.pathlib import make_numbered_dir
 from _pytest.pytester import Pytester
 import pytest
@@ -1280,6 +1282,41 @@ def test_meta_path():
         )
         assert pytester.runpytest().ret == 0
 
+
+    def test_rootpath_base(self, pytester: Pytester, monkeypatch: MonkeyPatch) -> None:
+        """
+        Base cases for get rootpath from AssertionState
+        """
+        from _pytest.assertion import AssertionState
+        config = pytester.parseconfig()
+        monkeypatch.chdir(pytester.path)
+        state = AssertionState(config, "rewrite")
+        assert state.rootpath == str(pytester.path)
+        new_rootpath = pytester.path + "/test"
+        if not os.path.exists(new_rootpath):
+            os.mkdir(new_rootpath)
+        monkeypatch.chdir(new_rootpath)
+        state = AssertionState(config, "rewrite")
+        assert state.rootpath == new_rootpath
+
+
+    @pytest.mark.skipif(
+        sys.platform.startswith("win32"), reason="cannot remove cwd on Windows"
+    )
+    @pytest.mark.skipif(
+        sys.platform.startswith("sunos5"), reason="cannot remove cwd on Solaris"
+    )
+    def test_rootpath_cwd_removed(self, pytester: Pytester, monkeypatch: MonkeyPatch) -> None:
+        # Setup conditions for py's trying to os.getcwd() on py34
+        # when current working directory doesn't exist (previously triggered via xdist only).
+        # Ref: https://github.com/pytest-dev/py/pull/207
+        from _pytest.assertion import AssertionState
+        config = pytester.parseconfig()
+        monkeypatch.setattr(target=os, name="getcwd", value=Mock(side_effect=FileNotFoundError))
+        state = AssertionState(config, "rewrite")
+        assert state.rootpath ==  os.path.abspath(os.sep)
+
+
     def test_write_pyc(self, pytester: Pytester, tmp_path) -> None:
         from _pytest.assertion import AssertionState
         from _pytest.assertion.rewrite import _write_pyc