Mock the settings rather than monkeypatching external modules

tests/gui/conftest.py

@@ -21,34 +21,25 @@ def get_qt_app() -> Application:
 
 def generate_isolated_updater(
     tmp_path: Path,
-    monkeypatch: MonkeyPatch,
-    app_mocker: Optional[MockerFixture] = None,
+    mocker: MockerFixture,
+    mock_app: bool = False,
 ) -> UpdaterThread:
     """Generate an Updater class with its own settings."""
-    if app_mocker:
-        app = app_mocker.MagicMock()
-    else:
-        app = get_qt_app()
+    app = mocker.MagicMock() if mock_app else get_qt_app()
 
     dummy = Dummy()
-    # XXX: We can monkey-patch global state without wrapping it in a context manager, or
-    # worrying that it will leak between tests, for two reasons:
-    #
-    # 1. Parallel tests in PyTest take place in different processes.
-    # 2. The monkeypatch fixture tears down the monkey-patch after each test ends.
-    monkeypatch.setattr(util, "get_config_dir", lambda: tmp_path)
+    mocker.patch("dangerzone.settings.get_config_dir", return_value=tmp_path)
+
     dangerzone = DangerzoneGui(app, isolation_provider=dummy)
     updater = UpdaterThread(dangerzone)
     return updater
 
 
 @pytest.fixture
-def updater(
-    tmp_path: Path, monkeypatch: MonkeyPatch, mocker: MockerFixture
-) -> UpdaterThread:
-    return generate_isolated_updater(tmp_path, monkeypatch, mocker)
+def updater(tmp_path: Path, mocker: MockerFixture) -> UpdaterThread:
+    return generate_isolated_updater(tmp_path, mocker, mock_app=True)
 
 
 @pytest.fixture
-def qt_updater(tmp_path: Path, monkeypatch: MonkeyPatch) -> UpdaterThread:
-    return generate_isolated_updater(tmp_path, monkeypatch)
+def qt_updater(tmp_path: Path, mocker: MockerFixture) -> UpdaterThread:
+    return generate_isolated_updater(tmp_path, mocker, mock_app=False)

tests/gui/test_updater.py

@@ -48,9 +48,7 @@ def test_default_updater_settings(updater: UpdaterThread) -> None:
     )
 
 
-def test_pre_0_4_2_settings(
-    tmp_path: Path, monkeypatch: MonkeyPatch, mocker: MockerFixture
-) -> None:
+def test_pre_0_4_2_settings(tmp_path: Path, mocker: MockerFixture) -> None:
     """Check settings of installations prior to 0.4.2.
 
     Check that installations that have been upgraded from a version < 0.4.2 to >= 0.4.2
@@ -58,7 +56,7 @@ def test_pre_0_4_2_settings(
     in their settings.json file.
     """
     save_settings(tmp_path, default_settings_0_4_1())
-    updater = generate_isolated_updater(tmp_path, monkeypatch, mocker)
+    updater = generate_isolated_updater(tmp_path, mocker, mock_app=True)
     assert (
         updater.dangerzone.settings.get_updater_settings() == default_updater_settings()
     )
@@ -83,12 +81,10 @@ def test_post_0_4_2_settings(
     # version is 0.4.3.
     expected_settings = default_updater_settings()
     expected_settings["updater_latest_version"] = "0.4.3"
-    monkeypatch.setattr(
-        settings, "get_version", lambda: expected_settings["updater_latest_version"]
-    )
+    monkeypatch.setattr(settings, "get_version", lambda: "0.4.3")
 
     # Ensure that the Settings class will correct the latest version field to 0.4.3.
-    updater = generate_isolated_updater(tmp_path, monkeypatch, mocker)
+    updater = generate_isolated_updater(tmp_path, mocker, mock_app=True)
     assert updater.dangerzone.settings.get_updater_settings() == expected_settings
 
     # Simulate an updater check that found a newer Dangerzone version (e.g., 0.4.4).
@@ -118,9 +114,7 @@ def test_linux_no_check(updater: UpdaterThread, monkeypatch: MonkeyPatch) -> Non
     assert updater.dangerzone.settings.get_updater_settings() == expected_settings
 
 
-def test_user_prompts(
-    updater: UpdaterThread, monkeypatch: MonkeyPatch, mocker: MockerFixture
-) -> None:
+def test_user_prompts(updater: UpdaterThread, mocker: MockerFixture) -> None:
     """Test prompting users to ask them if they want to enable update checks."""
     # First run
     #
@@ -370,8 +364,6 @@ def test_update_errors(
 def test_update_check_prompt(
     qtbot: QtBot,
     qt_updater: UpdaterThread,
-    monkeypatch: MonkeyPatch,
-    mocker: MockerFixture,
 ) -> None:
     """Test that the prompt to enable update checks works properly."""
     # Force Dangerzone to check immediately for updates

tests/test_settings.py

@@ -21,6 +21,13 @@ def default_settings_0_4_1() -> dict:
     }
 
 
+def save_settings(tmp_path: Path, settings: dict) -> None:
+    """Mimic the way Settings save a dictionary to a settings.json file."""
+    settings_filename = tmp_path / "settings.json"
+    with open(settings_filename, "w") as settings_file:
+        json.dump(settings, settings_file, indent=4)
+
+
 def test_no_settings_file_creates_new_one(
     tmp_path: Path,
     mocker: MockerFixture,