test: 补充知识处理、检索与 Agent 回归用例

覆盖切块、向量检索、工具调用和历史预算；模型相关用例使用桩。

backend/tests/agents/test_history_memory.py

@@ -0,0 +1,112 @@
+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from agno.models.message import Message
+from agno.run.response import RunResponse, RunStatus
+
+from app.agents.history_memory import (
+    TOOL_RESULT_STUB,
+    BoundedHistoryMemory,
+    bound_history,
+    is_context_overflow,
+)
+
+
+def _turn(n: int, tool_result: str = "", answer: str = "answer") -> list:
+    """user -> (assistant tool call -> tool result) -> assistant answer."""
+    messages = [Message(role="user", content=f"question {n}")]
+    if tool_result:
+        messages.append(
+            Message(
+                role="assistant",
+                content="",
+                tool_calls=[{"id": f"call{n}", "type": "function", "function": {"name": "search_knowledge_base", "arguments": "{}"}}],
+            )
+        )
+        messages.append(
+            Message(role="tool", tool_call_id=f"call{n}", tool_name="search_knowledge_base", content=tool_result)
+        )
+    messages.append(Message(role="assistant", content=answer))
+    return messages
+
+
+class TestBoundHistory:
+    def test_tool_results_are_stubbed_and_pairing_kept(self):
+        messages = _turn(1, tool_result="x" * 50_000)
+        bounded = bound_history(messages, max_chars=100_000)
+        tool = [m for m in bounded if m.role == "tool"][0]
+        assert tool.content == TOOL_RESULT_STUB.format(tool="search_knowledge_base")
+        assert tool.tool_call_id == "call1"
+        assert [m.role for m in bounded] == ["user", "assistant", "tool", "assistant"]
+
+    def test_originals_untouched(self):
+        messages = _turn(1, tool_result="original")
+        bound_history(messages, max_chars=100_000)
+        assert messages[2].content == "original"
+
+    def test_oldest_turns_dropped_whole_past_budget(self):
+        messages = _turn(1, answer="a" * 300) + _turn(2, answer="b" * 300) + _turn(3, answer="c" * 300)
+        bounded = bound_history(messages, max_chars=700)
+        assert [m.content for m in bounded if m.role == "user"] == ["question 2", "question 3"]
+
+    def test_zero_budget_keeps_nothing(self):
+        assert bound_history(_turn(1) + _turn(2), max_chars=0) == []
+
+    def test_tool_pair_never_split(self):
+        messages = _turn(1, tool_result="t" * 10, answer="z" * 200) + _turn(2, answer="w" * 10)
+        bounded = bound_history(messages, max_chars=120)
+        roles = [m.role for m in bounded]
+        assert roles == ["user", "assistant"]
+
+    def test_unknown_tool_name_still_stubbed(self):
+        msg = Message(role="tool", tool_call_id="c", content="big")
+        assert bound_history([msg], max_chars=1000)[0].content == TOOL_RESULT_STUB.format(tool="tool")
+
+
+class TestBoundedHistoryMemory:
+    def _memory(self) -> BoundedHistoryMemory:
+        memory = BoundedHistoryMemory()
+        memory.history_max_chars = 10_000
+        run = RunResponse(run_id="r1", session_id="s1", messages=_turn(1, tool_result="k" * 5_000))
+        run.status = RunStatus.completed
+        memory.runs = {"s1": [run]}
+        return memory
+
+    def test_replayed_history_is_bounded_but_stored_run_is_not(self):
+        memory = self._memory()
+        history = memory.get_messages_from_last_n_runs(session_id="s1", last_n=5)
+        tool = [m for m in history if m.role == "tool"][0]
+        assert tool.content.startswith("[")
+        stored_tool = [m for m in memory.runs["s1"][0].messages if m.role == "tool"][0]
+        assert stored_tool.content == "k" * 5_000
+
+    def test_without_history_is_temporary(self):
+        memory = self._memory()
+        with memory.without_history():
+            assert memory.get_messages_from_last_n_runs(session_id="s1", last_n=5) == []
+        assert memory.get_messages_from_last_n_runs(session_id="s1", last_n=5)
+
+
+class TestIsContextOverflow:
+    def test_provider_wordings(self):
+        assert is_context_overflow(Exception("This model's maximum context length is 128000 tokens"))
+        assert is_context_overflow(Exception("Error code: 400 - context_length_exceeded"))
+        assert is_context_overflow(Exception("prompt is too long: 210000 tokens > 200000 maximum"))
+        assert is_context_overflow(Exception("The input token count (1200000) exceeds the maximum"))
+
+    def test_other_errors_not_matched(self):
+        assert not is_context_overflow(Exception("rate limit exceeded"))
+        assert not is_context_overflow(Exception("invalid api key"))