ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

chapter3/agentic-rag/test_history_limit_zero.py

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+"""conversation_history_limit=0 must omit history, not include all via [-0:]."""
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+from agent import AgenticRAG
+
+
+def test_history_limit_zero_omits_history():
+    agent = object.__new__(AgenticRAG)
+    agent.config = SimpleNamespace(
+        agent=SimpleNamespace(conversation_history_limit=0)
+    )
+    agent._get_system_prompt = lambda: "sys"
+    agent.conversation_history = [
+        {"role": "user", "content": "old1"},
+        {"role": "assistant", "content": "old2"},
+    ]
+    msgs = agent._build_messages("new question")
+    assert msgs == [
+        {"role": "system", "content": "sys"},
+        {"role": "user", "content": "new question"},
+    ]
+
+
+def test_positive_history_limit_still_keeps_tail():
+    agent = object.__new__(AgenticRAG)
+    agent.config = SimpleNamespace(
+        agent=SimpleNamespace(conversation_history_limit=1)
+    )
+    agent._get_system_prompt = lambda: "sys"
+    agent.conversation_history = [
+        {"role": "user", "content": "old1"},
+        {"role": "assistant", "content": "old2"},
+    ]
+    msgs = agent._build_messages("new question")
+    assert msgs == [
+        {"role": "system", "content": "sys"},
+        {"role": "assistant", "content": "old2"},
+        {"role": "user", "content": "new question"},
+    ]