Fix and test MemoryStep (#432)

* Test MemoryStep
* Remove unused MemoryStep.raw attribute

src/smolagents/memory.py

@@ -37,9 +37,8 @@ class ToolCall:
         }
 
 
+@dataclass
 class MemoryStep:
-    raw: Any  # This is a placeholder for the raw data that the agent logs
-
     def dict(self):
         return asdict(self)
 

tests/test_memory.py

@@ -1,7 +1,10 @@
+import pytest
+
 from smolagents.memory import (
     ActionStep,
     AgentMemory,
     ChatMessage,
+    MemoryStep,
     Message,
     MessageRole,
     PlanningStep,
@@ -18,6 +21,21 @@ class TestAgentMemory:
         assert memory.steps == []
 
 
+class TestMemoryStep:
+    def test_initialization(self):
+        step = MemoryStep()
+        assert isinstance(step, MemoryStep)
+
+    def test_dict(self):
+        step = MemoryStep()
+        assert step.dict() == {}
+
+    def test_to_messages(self):
+        step = MemoryStep()
+        with pytest.raises(NotImplementedError):
+            step.to_messages()
+
+
 def test_action_step_to_messages():
     action_step = ActionStep(
         model_input_messages=[Message(role=MessageRole.USER, content="Hello")],