fix: harden openai-compatible provider responses

tests/test_provider_tools.py

@@ -1,7 +1,10 @@
 from types import SimpleNamespace
 
+import pytest
+
 from llm.core.types import LLMInput, Message, Role, ToolDefinition
 from llm.providers.claude import ClaudeProvider
+from llm.providers.constants import EMPTY_FILTERED_RESPONSE_ERROR
 from llm.providers.openai import OpenAIProvider
 
 
@@ -14,21 +17,20 @@ def _tool() -> ToolDefinition:
 
 
 class _OpenAICompletions:
-    def __init__(self) -> None:
+    def __init__(self, response: SimpleNamespace | None = None) -> None:
         self.params = None
+        self.response = response
 
     def create(self, **params):
         self.params = params
-        return SimpleNamespace(
-            choices=[SimpleNamespace(message=SimpleNamespace(content="ok", tool_calls=None), finish_reason="stop")],
-            model=params["model"],
-            usage=SimpleNamespace(prompt_tokens=1, completion_tokens=1, total_tokens=2),
-        )
+        if self.response:
+            return self.response
+        return _openai_response(model=params["model"])
 
 
 class _OpenAIClient:
-    def __init__(self) -> None:
-        self.completions = _OpenAICompletions()
+    def __init__(self, response: SimpleNamespace | None = None) -> None:
+        self.completions = _OpenAICompletions(response=response)
         self.chat = SimpleNamespace(completions=self.completions)
 
 
@@ -52,6 +54,16 @@ class _AnthropicClient:
         self.api_key = "test"
 
 
+def _openai_response(**overrides) -> SimpleNamespace:
+    defaults = {
+        "choices": [SimpleNamespace(message=SimpleNamespace(content="ok", tool_calls=None), finish_reason="stop")],
+        "model": "gpt-4o-mini",
+        "usage": SimpleNamespace(prompt_tokens=1, completion_tokens=1, total_tokens=2),
+    }
+    defaults.update(overrides)
+    return SimpleNamespace(**defaults)
+
+
 def test_openai_provider_serializes_tools_for_chat_completions():
     provider = OpenAIProvider(api_key="test")
     client = _OpenAIClient()
@@ -72,6 +84,36 @@ def test_openai_provider_serializes_tools_for_chat_completions():
     ]
 
 
+def test_openai_provider_can_be_constructed_without_credentials(monkeypatch):
+    monkeypatch.delenv("OPENAI_API_KEY", raising=False)
+
+    provider = OpenAIProvider()
+
+    assert provider.validate_config() is False
+
+
+def test_openai_provider_rejects_empty_or_filtered_responses():
+    provider = OpenAIProvider(api_key="test")
+
+    for response in [
+        _openai_response(choices=[]),
+        _openai_response(choices=[SimpleNamespace(message=None, finish_reason="content_filter")]),
+    ]:
+        provider.client = _OpenAIClient(response=response)
+        with pytest.raises(ValueError, match=EMPTY_FILTERED_RESPONSE_ERROR):
+            provider.generate(LLMInput(messages=[Message(role=Role.USER, content="hi")]))
+
+
+def test_openai_provider_allows_missing_usage():
+    provider = OpenAIProvider(api_key="test")
+    provider.client = _OpenAIClient(response=_openai_response(usage=None))
+
+    output = provider.generate(LLMInput(messages=[Message(role=Role.USER, content="hi")]))
+
+    assert output.content == "ok"
+    assert output.usage is None
+
+
 def test_claude_provider_serializes_tools_for_messages_api():
     provider = ClaudeProvider(api_key="test")
     client = _AnthropicClient()