Add tests for legacy load by url and fix bugs (#19078)

tests/test_feature_extraction_common.py

@@ -182,6 +182,12 @@ class FeatureExtractorUtilTester(unittest.TestCase):
             # This check we did call the fake head request
             mock_head.assert_called()
 
+    def test_legacy_load_from_url(self):
+        # This test is for deprecated behavior and can be removed in v5
+        _ = Wav2Vec2FeatureExtractor.from_pretrained(
+            "https://huggingface.co/hf-internal-testing/tiny-random-wav2vec2/resolve/main/preprocessor_config.json"
+        )
+
 
 @is_staging_test
 class FeatureExtractorPushToHubTester(unittest.TestCase):