Testing: Use config_dialog fixture in test_change_ui_theme_and_color_…

…scheme

This simplifies the test and also fixes an error when interacting with
other tests for Preferences.

spyder/plugins/appearance/tests/test_confpage.py

@@ -6,42 +6,45 @@
 # (see LICENSE.txt for details)
 # -----------------------------------------------------------------------------
 
+# Third-party imports
+import pytest
+
 # Local imports
 from spyder.api.plugins import Plugins
-from spyder.api.plugin_registration.registry import PLUGIN_REGISTRY
 from spyder.plugins.appearance.plugin import Appearance
 from spyder.plugins.preferences.api import SpyderConfigPage
-from spyder.plugins.preferences.tests.conftest import MainWindowMock
-from spyder.utils.stylesheet import APP_STYLESHEET
+from spyder.plugins.preferences.tests.conftest import (
+    config_dialog, MainWindowMock)
 
 
-def test_change_ui_theme_and_color_scheme(qtbot, mocker):
+@pytest.mark.parametrize(
+    'config_dialog',
+    [[MainWindowMock, [], [Appearance]]],
+    indirect=True)
+def test_change_ui_theme_and_color_scheme(config_dialog, mocker, qtbot):
     """Test that changing color scheme or UI theme works as expected."""
     # Patch methods whose calls we want to check
     mocker.patch.object(SpyderConfigPage, "prompt_restart_required")
 
-    # Create main window
-    main = MainWindowMock()
-    main.setStyleSheet(str(APP_STYLESHEET))
-
-    # Register Appearance
-    appearance = PLUGIN_REGISTRY.register_plugin(main, Appearance)
+    # Get reference to main window and appearance
+    main = config_dialog.parent()
+    appearance = main.get_plugin(Plugins.Appearance)
 
-    # Create preferences page
-    preferences = main.get_plugin(Plugins.Preferences)
-    preferences.open_dialog(None)
-
-    # Get widget page to interact with
-    container = preferences.get_container()
-    dlg = container.dialog
-    widget = dlg.get_page()
+    # Get reference to Preferences dialog and widget page to interact with
+    dlg = config_dialog
+    widget = config_dialog.get_page()
 
     # List of color schemes
     names = widget.get_option('names')
 
     # Assert no restarts have been requested so far.
     assert SpyderConfigPage.prompt_restart_required.call_count == 0
 
+    # Assert default UI theme is 'automatic' and interface is dark. The other
+    # tests below depend on this.
+    assert appearance.get_conf('ui_theme') == 'automatic'
+    assert appearance._is_dark_interface
+
     # Change to another dark color scheme
     widget.schemes_combobox.setCurrentIndex(names.index('monokai'))
     dlg.apply_btn.click()

spyder/plugins/preferences/tests/conftest.py

@@ -101,6 +101,7 @@ def get_plugin(self, plugin_name, error=False):
         setattr(self._main, 'set_prefs_size',
                 types.MethodType(set_prefs_size, self._main))
 
+        PLUGIN_REGISTRY.reset()
         PLUGIN_REGISTRY.sig_plugin_ready.connect(self._main.register_plugin)
         PLUGIN_REGISTRY.register_plugin(self._main, Preferences)