fix record_trampoline_hit when tmpdir changed working directory

Author: Otto-AA

e2e_projects/my_lib/src/my_lib/__init__.py

@@ -234,3 +234,7 @@ def divide(a: int, b: int):
             ),
         )
         raise Exception(f'Cannot divide if {b=} cannot be 0!!!')
+
+def write_into_file(path: str):
+    with open(path, 'w') as file:
+        file.write("Hello")

e2e_projects/my_lib/tests/test_my_lib.py

@@ -172,3 +172,13 @@ def test_private_class_classmethod():
 def test_divide():
     with pytest.raises(Exception, match='.*cannot be 0!!!'):
         divide(1, 0)
+
+def test_tmp_dir_switch(tmpdir):
+    """Verify that mutmut works with the tmpdir fixture"""
+    # change to tmp directory
+    with tmpdir.as_cwd():
+        write_into_file("foo.txt")
+
+        with open("foo.txt", "r", encoding='utf-8') as file:
+            data = file.read()
+            assert "Hello" in data

src/mutmut/__main__.py

@@ -121,7 +121,7 @@
 def record_trampoline_hit(name: str, caller: str | None = None) -> None:
     assert not name.startswith("src."), "Failed trampoline hit. Module name starts with `src.`, which is invalid"
 
-    source_paths = [p.resolve(strict=True) for p in Config.get().source_paths]
+    mutated_source_paths = Config.get().resolved_mutated_source_paths
 
     if Config.get().max_stack_depth != -1:
         f = inspect.currentframe()
@@ -132,7 +132,7 @@ def record_trampoline_hit(name: str, caller: str | None = None) -> None:
             if "pytest" in filename or "hammett" in filename or "unittest" in filename:
                 break
             file_path = Path(filename).resolve(strict=True)
-            if any(path in file_path.parents for path in source_paths):
+            if any(path in file_path.parents for path in mutated_source_paths):
                 # only include stack frames of user-code; exclude mutmut and 3rd library stack frames
                 c -= 1
 

src/mutmut/configuration.py

@@ -103,6 +103,9 @@ def _load_config() -> Config:
     source_paths = [Path(path) for path in s("source_paths", [])]
     source_paths = source_paths or paths_to_mutate or [Path(path) for path in _guess_source_paths()]
 
+    # We resolve at startup, s.t. we are still in the current working directory (and no tests modified the directory)
+    resolved_mutated_source_paths = [Path.cwd().resolve(strict=True) / "mutants" / p for p in source_paths]
+
     tests_dir = s("tests_dir", [])
     if tests_dir:
         warnings.warn(
@@ -135,6 +138,7 @@ def _load_config() -> Config:
         debug=s("debug", False),
         mutate_only_covered_lines=s("mutate_only_covered_lines", False),
         source_paths=source_paths,
+        resolved_mutated_source_paths=resolved_mutated_source_paths,
         pytest_add_cli_args=s("pytest_add_cli_args", []),
         pytest_add_cli_args_test_selection=pytest_add_cli_args_test_selection,
         timeout_multiplier=s("timeout_multiplier", 15.0),
@@ -164,6 +168,7 @@ class Config:
     max_stack_depth: int
     debug: bool
     source_paths: list[Path]
+    resolved_mutated_source_paths: list[Path]
     pytest_add_cli_args: list[str]
     pytest_add_cli_args_test_selection: list[str]
     mutate_only_covered_lines: bool

tests/e2e/test_e2e_my_lib.py

@@ -109,6 +109,16 @@ def test_my_lib_result_snapshot():
                 "my_lib.xǁ_PrivateClassǁget_question__mutmut_3": 0,
                 "my_lib.xǁ_PrivateClassǁget_answer__mutmut_1": 0,
                 "my_lib.x_divide__mutmut_1": 1,
+                "my_lib.x_write_into_file__mutmut_1": 1,
+                "my_lib.x_write_into_file__mutmut_2": 1,
+                "my_lib.x_write_into_file__mutmut_3": 1,
+                "my_lib.x_write_into_file__mutmut_4": 1,
+                "my_lib.x_write_into_file__mutmut_5": 1,
+                "my_lib.x_write_into_file__mutmut_6": 1,
+                "my_lib.x_write_into_file__mutmut_7": 1,
+                "my_lib.x_write_into_file__mutmut_8": 0,
+                "my_lib.x_write_into_file__mutmut_9": 1,
+                "my_lib.x_write_into_file__mutmut_10": 1,
             }
         }
     )

tests/mutation/test_mutation.py

@@ -1226,6 +1226,7 @@ def test_record_trampoline_hit_records_caller(monkeypatch):
     cfg = Mock(spec=Config)
     cfg.max_stack_depth = -1
     cfg.source_paths = []
+    cfg.resolved_mutated_source_paths = []
     cfg.track_dependencies = True
     monkeypatch.setattr(Config, "get", lambda: cfg)
 
@@ -1244,6 +1245,7 @@ def test_record_trampoline_hit_skips_caller_when_disabled(monkeypatch):
     cfg = Mock(spec=Config)
     cfg.max_stack_depth = -1
     cfg.source_paths = []
+    cfg.resolved_mutated_source_paths = []
     cfg.track_dependencies = False
     monkeypatch.setattr(Config, "get", lambda: cfg)
 
@@ -1318,6 +1320,7 @@ def _config_for_invalidation(**overrides):
         max_stack_depth=-1,
         debug=False,
         source_paths=[pathlib.Path("src")],
+        resolved_mutated_source_paths=[(pathlib.Path("mutants") / "src").absolute()],
         pytest_add_cli_args=[],
         pytest_add_cli_args_test_selection=[],
         mutate_only_covered_lines=False,

tests/test_configuration.py

@@ -64,6 +64,7 @@ def _get_config(only_mutate: list[str], do_not_mutate: list[str]) -> Config:
             max_stack_depth=-1,
             debug=False,
             source_paths=[],
+            resolved_mutated_source_paths=[],
             pytest_add_cli_args=[],
             pytest_add_cli_args_test_selection=[],
             mutate_only_covered_lines=False,