Suggestions for better debugging (#765)

Please feel free to disregard any changes you disagree with

tests/unit_tests/agents/test_agent.py

@@ -19,8 +19,8 @@ class FakeListLLM(LLM, BaseModel):
     def _call(self, prompt: str, stop: Optional[List[str]] = None) -> str:
         """Increment counter, and then return response in that index."""
         self.i += 1
-        print(self.i)
-        print(self.responses)
+        print(f"=== Mock Response #{self.i} ===")
+        print(self.responses[self.i])
         return self.responses[self.i]
 
     @property
@@ -92,7 +92,10 @@ def test_agent_with_callbacks_global() -> None:
     output = agent.run("when was langchain made")
     assert output == "curses foiled again"
 
-    # 1 top level chain run, 2 LLMChain runs, 2 LLM runs, 1 tool run
+    # 1 top level chain run runs, 2 LLMChain runs, 2 LLM runs, 1 tool run
+    assert handler.chain_starts == handler.chain_ends == 3
+    assert handler.llm_starts == handler.llm_ends == 2
+    assert handler.tool_starts == handler.tool_ends == 1
     assert handler.starts == 6
     # 1 extra agent end
     assert handler.ends == 7
@@ -130,7 +133,10 @@ def test_agent_with_callbacks_local() -> None:
     output = agent.run("when was langchain made")
     assert output == "curses foiled again"
 
-    # 1 top level chain run, 2 LLMChain runs, 2 LLM runs, 1 tool run
+    # 1 top level chain run, 2 LLMChain starts, 2 LLM runs, 1 tool run
+    assert handler.chain_starts == handler.chain_ends == 3
+    assert handler.llm_starts == handler.llm_ends == 2
+    assert handler.tool_starts == handler.tool_ends == 1
     assert handler.starts == 6
     # 1 extra agent end
     assert handler.ends == 7

tests/unit_tests/callbacks/fake_callback_handler.py

@@ -39,14 +39,25 @@ class FakeCallbackHandler(BaseModel, BaseCallbackHandler):
         """Whether to ignore agent callbacks."""
         return self.ignore_agent_
 
+    # add finer-grained counters for easier debugging of failing tests
+    chain_starts: int = 0
+    chain_ends: int = 0
+    llm_starts: int = 0
+    llm_ends: int = 0
+    tool_starts: int = 0
+    tool_ends: int = 0
+    agent_ends: int = 0
+
     def on_llm_start(
         self, serialized: Dict[str, Any], prompts: List[str], **kwargs: Any
     ) -> None:
         """Run when LLM starts running."""
+        self.llm_starts += 1
         self.starts += 1
 
     def on_llm_end(self, response: LLMResult, **kwargs: Any) -> None:
         """Run when LLM ends running."""
+        self.llm_ends += 1
         self.ends += 1
 
     def on_llm_error(
@@ -59,10 +70,12 @@ class FakeCallbackHandler(BaseModel, BaseCallbackHandler):
         self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
     ) -> None:
         """Run when chain starts running."""
+        self.chain_starts += 1
         self.starts += 1
 
     def on_chain_end(self, outputs: Dict[str, Any], **kwargs: Any) -> None:
         """Run when chain ends running."""
+        self.chain_ends += 1
         self.ends += 1
 
     def on_chain_error(
@@ -75,10 +88,12 @@ class FakeCallbackHandler(BaseModel, BaseCallbackHandler):
         self, serialized: Dict[str, Any], action: AgentAction, **kwargs: Any
     ) -> None:
         """Run when tool starts running."""
+        self.tool_starts += 1
         self.starts += 1
 
     def on_tool_end(self, output: str, **kwargs: Any) -> None:
         """Run when tool ends running."""
+        self.tool_ends += 1
         self.ends += 1
 
     def on_tool_error(
@@ -93,4 +108,5 @@ class FakeCallbackHandler(BaseModel, BaseCallbackHandler):
 
     def on_agent_finish(self, finish: AgentFinish, **kwargs: Any) -> None:
         """Run when agent ends running."""
+        self.agent_ends += 1
         self.ends += 1