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

chapter7/agent-cost-analysis/tests/test_chat_null_usage.py

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+"""Tracer.chat must tolerate response.usage == None (OpenAI-compatible providers)."""
+
+from types import SimpleNamespace
+
+import config
+from tracer import Tracer
+
+
+class _FakeClient:
+    def __init__(self, usage):
+        self.chat = SimpleNamespace(
+            completions=SimpleNamespace(create=self._create)
+        )
+        self._usage = usage
+
+    def _create(self, **_kwargs):
+        return SimpleNamespace(usage=self._usage)
+
+
+def test_chat_tolerates_null_usage():
+    tr = Tracer(_FakeClient(None), pricing=config.default_pricing())
+    resp = tr.chat(step="turn-1", tool="query_order", model="m", messages=[])
+    assert resp.usage is None
+    assert len(tr.spans) == 1
+    s = tr.spans[0]
+    assert s.prompt_tokens == 0
+    assert s.completion_tokens == 0
+    assert s.cost_usd == 0.0
+    assert s.latency_s >= 0.0
+
+
+def test_chat_keeps_real_usage():
+    usage = SimpleNamespace(
+        prompt_tokens=100,
+        completion_tokens=20,
+        prompt_tokens_details=SimpleNamespace(cached_tokens=10),
+    )
+    tr = Tracer(_FakeClient(usage), pricing=config.default_pricing())
+    tr.chat(step="turn-1", tool="query_order", model="m", messages=[])
+    s = tr.spans[0]
+    assert s.prompt_tokens == 100
+    assert s.completion_tokens == 20
+    assert s.cached_tokens == 10
+    assert s.cost_usd > 0