Harrison/add human prefix (#520)

Co-authored-by: Andrew Huang <jhuang16888@gmail.com>

tests/unit_tests/chains/test_conversation.py

@@ -19,6 +19,13 @@ def test_memory_ai_prefix() -> None:
     assert memory.buffer == "\nHuman: bar\nAssistant: foo"
 
 
+def test_memory_human_prefix() -> None:
+    """Test that human_prefix in the memory component works."""
+    memory = ConversationBufferMemory(memory_key="foo", human_prefix="Friend")
+    memory.save_context({"input": "bar"}, {"output": "foo"})
+    assert memory.buffer == "\nFriend: bar\nAI: foo"
+
+
 def test_conversation_chain_works() -> None:
     """Test that conversation chain works in basic setting."""
     llm = FakeLLM()