search plugin: do not crash on missing lang options, inform instead

mkdocs/contrib/search/__init__.py

@@ -13,20 +13,29 @@
 class LangOption(config_options.OptionallyRequired):
     """ Validate Language(s) provided in config are known languages. """
 
-    def lang_file_exists(self, lang):
-        path = os.path.join(base_path, 'lunr-language', f'lunr.{lang}.js')
-        return os.path.isfile(path)
+    def get_lunr_supported_lang(self, lang):
+        for lang_part in lang.split("_"):
+            lang_part = lang_part.lower()
+            if os.path.isfile(os.path.join(base_path, 'lunr-language', f'lunr.{lang_part}.js')):
+                return lang_part
 
     def run_validation(self, value):
         if isinstance(value, str):
             value = [value]
         elif not isinstance(value, (list, tuple)):
             raise config_options.ValidationError('Expected a list of language codes.')
-        for lang in value:
-            if lang != 'en' and not self.lang_file_exists(lang):
-                raise config_options.ValidationError(
-                    f'"{lang}" is not a supported language code.'
-                )
+        for lang in list(value):
+            if lang != 'en':
+                lang_detected = self.get_lunr_supported_lang(lang)
+                if not lang_detected:
+                    log.info(f"Option search.lang '{lang}' is not supported, falling back to 'en'")
+                    value.remove(lang)
+                    if 'en' not in value:
+                        value.append('en')
+                elif lang_detected != lang:
+                    value.remove(lang)
+                    value.append(lang_detected)
+                    log.info(f"Option search.lang '{lang}' switched to '{lang_detected}'")
         return value
 
 

mkdocs/tests/search_tests.py

@@ -60,11 +60,18 @@ def test_lang_bad_type(self):
 
     def test_lang_bad_code(self):
         option = search.LangOption()
-        self.assertRaises(ValidationError, option.validate, ['foo'])
+        value = option.validate(['foo'])
+        self.assertEqual(['en'], value)
 
     def test_lang_good_and_bad_code(self):
         option = search.LangOption()
-        self.assertRaises(ValidationError, option.validate, ['en', 'foo'])
+        value = option.validate(['en', 'foo'])
+        self.assertEqual(['en'], value)
+
+    def test_lang_good_and_bad_and_territory(self):
+        option = search.LangOption()
+        value = option.validate(['zh_CN', 'pt_BR', 'fr'])
+        self.assertEqual(['fr', 'en', 'pt'], value)
 
 
 class SearchPluginTests(unittest.TestCase):