Add test for override plugins

test/test_plugins.py

@@ -43,6 +43,10 @@ class TestPlugins(unittest.TestCase):
         self.assertNotIn('IgnoreNotInAllPluginIE', plugins_ie.keys())
         self.assertIn('InAllPluginIE', plugins_ie.keys())
 
+        # Don't load override extractors into plugins_ie
+        self.assertNotIn('OverrideGenericIE', plugins_ie.keys())
+        self.assertNotIn('_UnderscoreOverrideGenericIE', plugins_ie.keys())
+
     def test_postprocessor_classes(self):
         plugins_pp = load_plugins(PluginType.POSTPROCESSORS)
         self.assertIn('NormalPluginPP', plugins_pp.keys())
@@ -108,6 +112,19 @@ class TestPlugins(unittest.TestCase):
             sys.path.append(str(TEST_DATA_DIR))
             importlib.invalidate_caches()
 
+    def test_extractor_override_plugin(self):
+        for module_name in tuple(sys.modules):
+            if module_name.startswith(f'{PACKAGE_NAME}.extractor'):
+                del sys.modules[module_name]
+        plugins_ie = load_plugins(PluginType.EXTRACTORS)
+
+        from yt_dlp.extractor.generic import GenericIE
+
+        self.assertEqual(GenericIE.TEST_FIELD, 'override')
+        self.assertEqual(GenericIE.SECONDARY_TEST_FIELD, 'underscore-override')
+
+        self.assertEqual(GenericIE.IE_NAME, 'generic+override+underscore-override')
+
 
 if __name__ == '__main__':
     unittest.main()

test/testdata/yt_dlp_plugins/extractor/override.py

@@ -0,0 +1,5 @@
+from yt_dlp.extractor.generic import GenericIE
+
+
+class OverrideGenericIE(GenericIE, plugin_name='override'):
+    TEST_FIELD = 'override'

test/testdata/yt_dlp_plugins/extractor/overridetwo.py

@@ -0,0 +1,5 @@
+from yt_dlp.extractor.generic import GenericIE
+
+
+class _UnderscoreOverrideGenericIE(GenericIE, plugin_name='underscore-override'):
+    SECONDARY_TEST_FIELD = 'underscore-override'