WIP

src/_pytest/pathlib.py

@@ -522,32 +522,28 @@ def import_path(
         raise ImportError(path)
 
     if mode is ImportMode.importlib:
-        pkg_path = resolve_package_path(path)
-        if pkg_path is not None:
-            pkg_root = pkg_path.parent
-            names = list(path.with_suffix("").relative_to(pkg_root).parts)
-            if names[-1] == "__init__":
-                names.pop()
-            module_name = ".".join(names)
-        else:
-            pkg_root = path.parent
-            module_name = path.stem
-
-        print("IMPORTMODE")
-        print(f"  {path=}")
+        # Obtain the canonical name of this path if we can resolve it to a python package,
+        # and try to import it without changing sys.path.
+        # If it works, we import it and return the module.
+        _, module_name = resolve_pkg_root_and_module_name(path)
         try:
             importlib.import_module(module_name)
-        except (ImportError, ImportWarning) as e:
-            print(f"  FAILED: {e}")
+        except (ImportError, ImportWarning):
+            # Cannot be imported normally with the current sys.path, so fallback
+            # to the more complex import-path mechanism.
+            pass
         else:
-            print(f"  WORKED: {module_name}")
+            # Double check that the imported module is the one we
+            # were given, otherwise it is easy to import modules with common names like "test"
+            # from another location.
             mod = sys.modules[module_name]
             if mod.__file__ and Path(mod.__file__) == path:
                 return mod
 
+        # Could not import the module with the current sys.path, so we fall back
+        # to importing the file as a standalone module, not being a part of a package.
         module_name = module_name_from_path(path, root)
         with contextlib.suppress(KeyError):
-            print(f"  CACHED {module_name=}")
             return sys.modules[module_name]
 
         for meta_importer in sys.meta_path:
@@ -563,19 +559,9 @@ def import_path(
         sys.modules[module_name] = mod
         spec.loader.exec_module(mod)  # type: ignore[union-attr]
         insert_missing_modules(sys.modules, module_name)
-        print(f"  IMPORTED_AS {module_name=}")
         return mod
 
-    pkg_path = resolve_package_path(path)
-    if pkg_path is not None:
-        pkg_root = pkg_path.parent
-        names = list(path.with_suffix("").relative_to(pkg_root).parts)
-        if names[-1] == "__init__":
-            names.pop()
-        module_name = ".".join(names)
-    else:
-        pkg_root = path.parent
-        module_name = path.stem
+    pkg_root, module_name = resolve_pkg_root_and_module_name(path)
 
     # Change sys.path permanently: restoring it at the end of this function would cause surprising
     # problems because of delayed imports: for example, a conftest.py file imported by this function
@@ -717,6 +703,36 @@ def resolve_package_path(path: Path) -> Optional[Path]:
     return result
 
 
+def resolve_pkg_root_and_module_name(path: Path) -> Tuple[Path, str]:
+    """
+    Return the path to the directory of the root package that contains the
+    given Python file, and its module name:
+
+        src/
+            app/
+                __init__.py
+                core/
+                    __init__.py
+                    models.py
+
+    Passing the full path to `models.py` will yield Path("src") and "app.core.models".
+
+    If the given path does not belong to a package (missing __init__.py) files, returns
+    just the parent path and the name of the file as module name.
+    """
+    pkg_path = resolve_package_path(path)
+    if pkg_path is not None:
+        pkg_root = pkg_path.parent
+        names = list(path.with_suffix("").relative_to(pkg_root).parts)
+        if names[-1] == "__init__":
+            names.pop()
+        module_name = ".".join(names)
+    else:
+        pkg_root = path.parent
+        module_name = path.stem
+    return pkg_root, module_name
+
+
 def scandir(
     path: Union[str, "os.PathLike[str]"],
     sort_key: Callable[["os.DirEntry[str]"], object] = lambda entry: entry.name,

testing/test_pathlib.py

@@ -25,6 +25,7 @@
 from _pytest.pathlib import maybe_delete_a_numbered_dir
 from _pytest.pathlib import module_name_from_path
 from _pytest.pathlib import resolve_package_path
+from _pytest.pathlib import resolve_pkg_root_and_module_name
 from _pytest.pathlib import safe_exists
 from _pytest.pathlib import symlink_or_skip
 from _pytest.pathlib import visit
@@ -598,6 +599,29 @@ def test_module_name_from_path(self, tmp_path: Path) -> None:
         result = module_name_from_path(tmp_path / "__init__.py", tmp_path)
         assert result == "__init__"
 
+        # Modules which start with "." are considered relative and will not be imported
+        # unless part of a package, so we replace it with a "_" when generating the fake module name.
+        result = module_name_from_path(tmp_path / ".env/tests/test_foo.py", tmp_path)
+        assert result == "_env.tests.test_foo"
+
+    def test_resolve_pkg_root_and_module_name(self, tmp_path: Path) -> None:
+        # Create a directory structure first without __init__.py files.
+        (tmp_path / "src/app/core").mkdir(parents=True)
+        models_py = tmp_path / "src/app/core/models.py"
+        models_py.touch()
+        assert resolve_pkg_root_and_module_name(models_py) == (
+            models_py.parent,
+            "models",
+        )
+
+        # Create the __init__.py files, it should now resolve to a proper module name.
+        (tmp_path / "src/app/__init__.py").touch()
+        (tmp_path / "src/app/core/__init__.py").touch()
+        assert resolve_pkg_root_and_module_name(models_py) == (
+            tmp_path / "src",
+            "app.core.models",
+        )
+
     def test_insert_missing_modules(
         self, monkeypatch: MonkeyPatch, tmp_path: Path
     ) -> None:
@@ -734,14 +758,18 @@ def foo():
                     2
                     '''
                 """
-            )
+            ),
+            encoding="ascii",
         )
 
         monkeypatch.syspath_prepend(app.parent)
 
         test_path = path / ".tests/test_core.py"
         test_path.parent.mkdir(parents=True)
-        test_path.write_text("import app.core\n\ndef test(): pass")
+        test_path.write_text(
+            "import app.core\n\ndef test(): pass",
+            encoding="ascii",
+        )
 
     def test_import_using_normal_mechanism_first(
         self, monkeypatch: MonkeyPatch, pytester: Pytester