[HuggingFace Pipeline] add streaming support (#23852)

libs/partners/huggingface/tests/integration_tests/test_llms.py

@@ -0,0 +1,18 @@
+from typing import Generator
+
+from langchain_huggingface.llms import HuggingFacePipeline
+
+
+def test_huggingface_pipeline_streaming() -> None:
+    """Test streaming tokens from huggingface_pipeline."""
+    llm = HuggingFacePipeline.from_model_id(
+        model_id="gpt2", task="text-generation", pipeline_kwargs={"max_new_tokens": 10}
+    )
+    generator = llm.stream("Q: How do you say 'hello' in German? A:'", stop=["."])
+    stream_results_string = ""
+    assert isinstance(generator, Generator)
+
+    for chunk in generator:
+        assert isinstance(chunk, str)
+        stream_results_string = chunk
+    assert len(stream_results_string.strip()) > 1