test async methods signatures

tests/test_inference_async_client.py

@@ -22,10 +22,12 @@
 For completeness we also run a test on a simple task (`test_async_sentence_similarity`) and assume all other tasks
 work as well.
 """
+import inspect
+
 import pytest
 
 import huggingface_hub.inference._common
-from huggingface_hub import AsyncInferenceClient
+from huggingface_hub import AsyncInferenceClient, InferenceClient
 from huggingface_hub.inference._common import _is_tgi_server
 from huggingface_hub.inference._text_generation import FinishReason, InputToken
 from huggingface_hub.inference._text_generation import ValidationError as TextGenerationValidationError
@@ -150,3 +152,49 @@ async def test_async_sentence_similarity() -> None:
         ],
     )
     assert scores == [0.7785726189613342, 0.4587625563144684, 0.2906219959259033]
+
+
+def test_sync_vs_async_signatures() -> None:
+    client = InferenceClient()
+    async_client = AsyncInferenceClient()
+
+    # Some methods have to be tested separately.
+    special_methods = ["post", "text_generation"]
+
+    # Post: this is not automatically tested. No need to test its signature separately.
+
+    # Text-generation: return type changes from Iterable[...] to AsyncIterable[...] but input parameters are the same
+    sync_method = getattr(client, "text_generation")
+    assert not inspect.iscoroutinefunction(sync_method)
+    async_method = getattr(async_client, "text_generation")
+    assert inspect.iscoroutinefunction(async_method)
+
+    sync_sig = inspect.signature(sync_method)
+    async_sig = inspect.signature(async_method)
+    assert sync_sig.parameters == async_sig.parameters
+    assert sync_sig.return_annotation != async_sig.return_annotation
+
+    [name for name in dir(client) if (not name.startswith("_")) and inspect.ismethod(getattr(client, name))]
+
+    # Check that all methods are consistent between InferenceClient and AsyncInferenceClient
+    for name in dir(client):
+        if not inspect.ismethod(getattr(client, name)):  # not a method
+            continue
+        if name.startswith("_"):  # not public method
+            continue
+        if name in special_methods:  # tested separately
+            continue
+
+        # Check that the sync method is not async
+        sync_method = getattr(client, name)
+        assert not inspect.iscoroutinefunction(sync_method)
+
+        # Check that the async method is async
+        async_method = getattr(async_client, name)
+        assert inspect.iscoroutinefunction(async_method)
+
+        # Check that expected inputs and outputs are the same
+        sync_sig = inspect.signature(sync_method)
+        async_sig = inspect.signature(async_method)
+        assert sync_sig.parameters == async_sig.parameters
+        assert sync_sig.return_annotation == async_sig.return_annotation