Fix incorrect FileNotFoundError in load_nox_module (#571)

nox/tasks.py

@@ -50,18 +50,15 @@ def _load_and_exec_nox_module(global_config: Namespace) -> types.ModuleType:
     spec = importlib.util.spec_from_file_location(
         "user_nox_module", global_config.noxfile
     )
-    if not spec:
-        raise OSError(f"Could not get module spec from {global_config.noxfile}")
+    assert spec is not None  # If None, fatal importlib error, would crash anyway
 
     module = importlib.util.module_from_spec(spec)
-    if not module:
-        raise OSError(f"Noxfile {global_config.noxfile} is not a valid python module.")
+    assert module is not None  # If None, fatal importlib error, would crash anyway
 
     sys.modules["user_nox_module"] = module
 
     loader = spec.loader
-    if not loader:  # pragma: no cover
-        raise OSError(f"Could not get module loader for {global_config.noxfile}")
+    assert loader is not None  # If None, fatal importlib error, would crash anyway
     # See https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
     loader.exec_module(module)
     return module
@@ -101,8 +98,6 @@ def load_nox_module(global_config: Namespace) -> types.ModuleType | int:
         # invoked from) gets stored by the .invoke_from "option" in _options.
         os.chdir(noxfile_parent_dir)
 
-        return _load_and_exec_nox_module(global_config)
-
     except (VersionCheckFailed, InvalidVersionSpecifier) as error:
         logger.error(str(error))
         return 2
@@ -114,6 +109,8 @@ def load_nox_module(global_config: Namespace) -> types.ModuleType | int:
     except OSError:
         logger.exception(f"Failed to load Noxfile {global_config.noxfile}")
         return 2
+    else:
+        return _load_and_exec_nox_module(global_config)
 
 
 def merge_noxfile_options(

tests/test_tasks.py

@@ -20,7 +20,6 @@
 import json
 import os
 import platform
-from pathlib import Path
 from textwrap import dedent
 from unittest import mock
 
@@ -89,56 +88,13 @@ def test_load_nox_module_not_found(caplog, tmp_path):
     )
 
 
-def test_load_nox_module_IOError(caplog):
-
-    # Need to give it a noxfile that exists so load_nox_module can progress
-    # past FileNotFoundError
-    # use our own noxfile.py for this
-    our_noxfile = Path(__file__).parent.parent.joinpath("noxfile.py")
-    config = _options.options.namespace(noxfile=str(our_noxfile))
-
-    with mock.patch("nox.tasks.importlib.util.module_from_spec") as mock_load:
-        mock_load.side_effect = IOError
-
-        assert tasks.load_nox_module(config) == 2
-        assert "Failed to load Noxfile" in caplog.text
-
-
-def test_load_nox_module_OSError(caplog):
-
-    # Need to give it a noxfile that exists so load_nox_module can progress
-    # past FileNotFoundError
-    # use our own noxfile.py for this
-    our_noxfile = Path(__file__).parent.parent.joinpath("noxfile.py")
-    config = _options.options.namespace(noxfile=str(our_noxfile))
-
-    with mock.patch("nox.tasks.importlib.util.module_from_spec") as mock_load:
-        mock_load.side_effect = OSError
-
+def test_load_nox_module_os_error(caplog):
+    noxfile = os.path.join(RESOURCES, "noxfile.py")
+    config = _options.options.namespace(noxfile=noxfile)
+    with mock.patch("nox.tasks.check_nox_version", autospec=True) as version_checker:
+        version_checker.side_effect = OSError
         assert tasks.load_nox_module(config) == 2
-        assert "Failed to load Noxfile" in caplog.text
-
-
-def test_load_nox_module_invalid_spec():
-    our_noxfile = Path(__file__).parent.parent.joinpath("noxfile.py")
-    config = _options.options.namespace(noxfile=str(our_noxfile))
-
-    with mock.patch("nox.tasks.importlib.util.spec_from_file_location") as mock_spec:
-        mock_spec.return_value = None
-
-        with pytest.raises(IOError):
-            tasks._load_and_exec_nox_module(config)
-
-
-def test_load_nox_module_invalid_module():
-    our_noxfile = Path(__file__).parent.parent.joinpath("noxfile.py")
-    config = _options.options.namespace(noxfile=str(our_noxfile))
-
-    with mock.patch("nox.tasks.importlib.util.module_from_spec") as mock_spec:
-        mock_spec.return_value = None
-
-        with pytest.raises(IOError):
-            tasks._load_and_exec_nox_module(config)
+        assert f"Failed to load Noxfile {noxfile}" in caplog.text
 
 
 @pytest.fixture