allow passing of stop params into openai (#232)

langchain/llms/openai.py

@@ -82,7 +82,7 @@ class OpenAI(LLM, BaseModel):
         return values
 
     @property
-    def _default_params(self) -> Mapping[str, Any]:
+    def _default_params(self) -> Dict[str, Any]:
         """Get the default parameters for calling OpenAI API."""
         normal_params = {
             "temperature": self.temperature,
@@ -115,7 +115,10 @@ class OpenAI(LLM, BaseModel):
 
                 response = openai("Tell me a joke.")
         """
-        response = self.client.create(
-            model=self.model_name, prompt=prompt, stop=stop, **self._default_params
-        )
+        params = self._default_params
+        if stop is not None:
+            if "stop" in params:
+                raise ValueError("`stop` found in both the input and default params.")
+            params["stop"] = stop
+        response = self.client.create(model=self.model_name, prompt=prompt, **params)
         return response["choices"][0]["text"]

tests/integration_tests/llms/test_openai.py

@@ -26,3 +26,21 @@ def test_openai_extra_kwargs() -> None:
     # Test that if provided twice it errors
     with pytest.raises(ValueError):
         OpenAI(foo=3, model_kwargs={"foo": 2})
+
+
+def test_openai_stop_valid() -> None:
+    """Test openai stop logic on valid configuration."""
+    query = "write an ordered list of five items"
+    first_llm = OpenAI(stop="3", temperature=0)
+    first_output = first_llm(query)
+    second_llm = OpenAI(temperature=0)
+    second_output = second_llm(query, stop=["3"])
+    # Because it stops on new lines, shouldn't return anything
+    assert first_output == second_output
+
+
+def test_openai_stop_error() -> None:
+    """Test openai stop logic on bad configuration."""
+    llm = OpenAI(stop="3", temperature=0)
+    with pytest.raises(ValueError):
+        llm("write an ordered list of five items", stop=["\n"])