Disable assertion rewriting external modules

changelog/13403.bugfix.rst

@@ -0,0 +1 @@
+Disable assertion rewriting of external modules

src/_pytest/assertion/__init__.py

@@ -106,8 +106,14 @@ class AssertionState:
     def __init__(self, config: Config, mode) -> None:
         self.mode = mode
         self.trace = config.trace.root.get("assertion")
+        self.config = config
         self.hook: rewrite.AssertionRewritingHook | None = None
 
+    @property
+    def rootpath(self):
+        """Get current root path (current working dir)"""
+        return str(self.config.invocation_params.dir)
+
 
 def install_importhook(config: Config) -> rewrite.AssertionRewritingHook:
     """Try to install the rewrite hook, raise SystemError if it fails."""

src/_pytest/assertion/rewrite.py

@@ -239,7 +239,7 @@ def _should_rewrite(self, name: str, fn: str, state: AssertionState) -> bool:
         # rewritten if they match the naming convention for test files
         fn_path = PurePath(fn)
         for pat in self.fnpats:
-            if fnmatch_ex(pat, fn_path):
+            if fnmatch_ex(pat, fn_path) and fn_path.is_relative_to(state.rootpath):
                 state.trace(f"matched test file {fn!r}")
                 return True
 

src/_pytest/pytester.py

@@ -749,6 +749,15 @@ def chdir(self) -> None:
         This is done automatically upon instantiation.
         """
         self._monkeypatch.chdir(self.path)
+        self._monkeypatch.setattr(
+            self._request.config,
+            "invocation_params",
+            Config.InvocationParams(
+                args=self._request.config.invocation_params.args,
+                plugins=self._request.config.invocation_params.plugins,
+                dir=Path(self._path),
+            ),
+        )
 
     def _makefile(
         self,

testing/test_assertrewrite.py

@@ -12,6 +12,7 @@
 import inspect
 import marshal
 import os
+from os import mkdir
 from pathlib import Path
 import py_compile
 import re
@@ -35,6 +36,7 @@
 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
@@ -370,6 +372,7 @@ def test_rewrites_plugin_as_a_package(self, pytester: Pytester) -> None:
         pytester.makeconftest('pytest_plugins = ["plugin"]')
         pytester.makepyfile("def test(special_asserter): special_asserter(1, 2)\n")
         result = pytester.runpytest()
+
         result.stdout.fnmatch_lines(["*assert 1 == 2*"])
 
     def test_honors_pep_235(self, pytester: Pytester, monkeypatch) -> None:
@@ -1294,6 +1297,34 @@ 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()
+        state = AssertionState(config, "rewrite")
+        assert state.rootpath == str(config.invocation_params.dir)
+        new_rootpath = str(pytester.path / "test")
+        if not os.path.exists(new_rootpath):
+            os.mkdir(new_rootpath)
+        monkeypatch.setattr(
+            config,
+            "invocation_params",
+            Config.InvocationParams(
+                args=(),
+                plugins=(),
+                dir=Path(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_write_pyc(self, pytester: Pytester, tmp_path) -> None:
         from _pytest.assertion import AssertionState
         from _pytest.assertion.rewrite import _write_pyc
@@ -1971,6 +2002,95 @@ def test_simple_failure():
             assert hook.find_spec("file") is not None
             assert self.find_spec_calls == ["file"]
 
+    def test_assert_rewrites_only_rootpath(
+        self, pytester: Pytester, hook: AssertionRewritingHook, monkeypatch
+    ) -> None:
+        """Do not rewrite assertions in tests outside `AssertState.rootpath` (#13403)."""
+        pytester.makepyfile(
+            **{
+                "file.py": """\
+                    def test_simple_failure():
+                        assert 1 + 1 == 3
+                """
+            }
+        )
+        with mock.patch.object(hook, "fnpats", ["*.py"]):
+            assert hook.find_spec("file") is not None
+
+        rootpath = f"{os.getcwd()}/tests"
+        if not os.path.exists(rootpath):
+            mkdir(rootpath)
+        monkeypatch.setattr(
+            pytester._request.config,
+            "invocation_params",
+            Config.InvocationParams(
+                args=(),
+                plugins=(),
+                dir=Path(rootpath),
+            ),
+        )
+        with mock.patch.object(hook, "fnpats", ["*.py"]):
+            assert hook.find_spec("file") is None
+
+    def test_assert_rewrite_correct_for_conftfest(
+        self, pytester: Pytester, hook: AssertionRewritingHook, monkeypatch
+    ) -> None:
+        """Conftest is always rewritten regardless of the root dir"""
+        pytester.makeconftest(
+            """
+            import pytest
+            @pytest.fixture
+            def fix(): return 1
+        """
+        )
+
+        rootpath = f"{os.getcwd()}/tests"
+        if not os.path.exists(rootpath):
+            mkdir(rootpath)
+        monkeypatch.setattr(
+            pytester._request.config,
+            "invocation_params",
+            Config.InvocationParams(
+                args=(),
+                plugins=(),
+                dir=Path(rootpath),
+            ),
+        )
+        with mock.patch.object(hook, "fnpats", ["*.py"]):
+            assert hook.find_spec("conftest") is not None
+
+    def test_assert_rewrite_correct_for_plugins(
+        self, pytester: Pytester, hook: AssertionRewritingHook, monkeypatch
+    ) -> None:
+        """
+        Plugins has always been rewritten regardless of the root dir
+        """
+        pkgdir = pytester.mkpydir("plugin")
+        pkgdir.joinpath("__init__.py").write_text(
+            "import pytest\n"
+            "@pytest.fixture\n"
+            "def special_asserter():\n"
+            "    def special_assert(x, y):\n"
+            "        assert x == y\n"
+            "    return special_assert\n",
+            encoding="utf-8",
+        )
+        hook.mark_rewrite("plugin")
+        rootpath = f"{os.getcwd()}/tests"
+        if not os.path.exists(rootpath):
+            mkdir(rootpath)
+        monkeypatch.setattr(
+            pytester._request.config,
+            "invocation_params",
+            Config.InvocationParams(
+                args=(),
+                plugins=(),
+                dir=Path(rootpath),
+            ),
+        )
+        with mock.patch.object(hook, "fnpats", ["*.py"]):
+            assert hook.find_spec("plugin") is not None
+
     @pytest.mark.skipif(
         sys.platform.startswith("win32"), reason="cannot remove cwd on Windows"
     )