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2026-07-13 12:58:18 +08:00

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"""Red-green tests for multi-turn history threading in the reasoning agent.
Background — the regression these tests pin down:
The previous `_extract_user_input` returned ONLY the last user message's
text, so the chat-completions request was always
``[{system}, {user: <last user text>}]``. Every prior user/assistant turn
was discarded, so follow-up questions lost their conversation context (the
agno reference threads full history via Agno's Agent).
The fix replaces `_extract_user_input` with `_to_chat_messages`, which maps
the full AG-UI message list into the chat-completions `messages` array:
system prompt first, then every prior user/assistant turn in order. tool and
system messages from the input are skipped.
Two CRITICAL constraints these tests pin:
1. For a SINGLE user-message input the result MUST be exactly
``[{system}, {user: <text>}]`` — byte-equal to the previous single-turn
behaviour, because the aimock D6 fixtures replay that exact request.
2. The empty / no-user-message edge preserves the prior behaviour: an empty
user turn (``[{system}, {user: ""}]``).
The module imports heavy deps (ag_ui, openai, fastapi, starlette) at top
level, so we stub them before import — mirroring the stub pattern in
`test_forwarded_props.py`. Only the pure helper functions
(`_to_chat_messages`, `_coerce_content`) and the module-level `SYSTEM_PROMPT`
are exercised; none of the stubbed surfaces are touched.
"""
from __future__ import annotations
import importlib.util
import os
import sys
import types
import pytest
_STUBBED_MODULE_NAMES = (
"ag_ui",
"ag_ui.core",
"ag_ui.encoder",
"openai",
"fastapi",
"starlette",
"starlette.endpoints",
"starlette.requests",
"starlette.responses",
)
def _install_stubs() -> dict:
"""Stub the heavy top-level imports so `reasoning_agent` imports cheaply.
Returns a snapshot of the original `sys.modules` entries for every name
we overwrite, so the fixture can restore them on teardown. Without the
restore, stubbing shared modules (e.g. `starlette.responses` without
`PlainTextResponse`) leaks into sibling test modules that import the
real package and breaks them when this test runs first.
"""
saved = {name: sys.modules.get(name) for name in _STUBBED_MODULE_NAMES}
# ag_ui.core — every name the module imports, as bare sentinels.
ag_ui = types.ModuleType("ag_ui")
ag_ui.__path__ = [] # mark as package
ag_ui_core = types.ModuleType("ag_ui.core")
for name in (
"BaseEvent",
"EventType",
"ReasoningMessageContentEvent",
"ReasoningMessageEndEvent",
"ReasoningMessageStartEvent",
"RunAgentInput",
"RunErrorEvent",
"RunFinishedEvent",
"RunStartedEvent",
"TextMessageContentEvent",
"TextMessageEndEvent",
"TextMessageStartEvent",
):
setattr(ag_ui_core, name, object)
ag_ui_encoder = types.ModuleType("ag_ui.encoder")
setattr(ag_ui_encoder, "EventEncoder", object)
sys.modules["ag_ui"] = ag_ui
sys.modules["ag_ui.core"] = ag_ui_core
sys.modules["ag_ui.encoder"] = ag_ui_encoder
# openai — only `AsyncOpenAI` is referenced (lazily, inside the coroutine).
openai_mod = types.ModuleType("openai")
setattr(openai_mod, "AsyncOpenAI", object)
sys.modules["openai"] = openai_mod
# fastapi.FastAPI — instantiated at module import for the sub-app.
fastapi_mod = types.ModuleType("fastapi")
class _FakeFastAPI:
def __init__(self, *args, **kwargs):
pass
def mount(self, *args, **kwargs):
pass
setattr(fastapi_mod, "FastAPI", _FakeFastAPI)
sys.modules["fastapi"] = fastapi_mod
# starlette.{endpoints,requests,responses} — bare class sentinels.
starlette = types.ModuleType("starlette")
starlette.__path__ = []
endpoints = types.ModuleType("starlette.endpoints")
setattr(endpoints, "HTTPEndpoint", object)
requests = types.ModuleType("starlette.requests")
setattr(requests, "Request", object)
responses = types.ModuleType("starlette.responses")
setattr(responses, "StreamingResponse", object)
sys.modules["starlette"] = starlette
sys.modules["starlette.endpoints"] = endpoints
sys.modules["starlette.requests"] = requests
sys.modules["starlette.responses"] = responses
return saved
def _restore_modules(saved: dict) -> None:
"""Restore the original `sys.modules` entries captured by `_install_stubs`.
A `None` snapshot value means the module was absent before stubbing, so
we remove our stub entirely rather than leaving a sentinel behind.
"""
for name, original in saved.items():
if original is None:
sys.modules.pop(name, None)
else:
sys.modules[name] = original
@pytest.fixture
def reasoning_agent():
"""Load `src/agents/reasoning_agent.py` directly with heavy deps stubbed.
We load the file by path under a private module name (not `import agents.
reasoning_agent`) so this test is independent of whatever stub another
test module may have installed for `agents.reasoning_agent` in
`sys.modules` (e.g. the autouse fixture in `test_forwarded_props.py`
leaves an `agents` package sentinel behind).
"""
saved = _install_stubs()
here = os.path.dirname(os.path.abspath(__file__))
src = os.path.normpath(
os.path.join(here, "..", "..", "src", "agents", "reasoning_agent.py")
)
mod_name = "_reasoning_agent_under_test"
sys.modules.pop(mod_name, None)
try:
spec = importlib.util.spec_from_file_location(mod_name, src)
mod = importlib.util.module_from_spec(spec)
sys.modules[mod_name] = mod
spec.loader.exec_module(mod)
yield mod
finally:
sys.modules.pop(mod_name, None)
_restore_modules(saved)
class _Msg:
"""Minimal AG-UI message stand-in (the helper only reads role/content)."""
def __init__(self, role, content=""):
self.role = role
self.content = content
def test_single_user_message_is_byte_equal_to_legacy_shape(reasoning_agent):
"""The aimock-fixture-critical invariant: a single user message must yield
EXACTLY ``[{system}, {user: <text>}]`` — same bytes as the old
single-turn `_extract_user_input` path produced."""
result = reasoning_agent._to_chat_messages([_Msg("user", "What is 2+2?")])
assert result == [
{"role": "system", "content": reasoning_agent.SYSTEM_PROMPT},
{"role": "user", "content": "What is 2+2?"},
]
def test_multi_turn_history_is_threaded_in_order(reasoning_agent):
"""All prior user/assistant turns must be threaded in order (the fix) —
not just the last user message (the regression)."""
msgs = [
_Msg("user", "What is 2+2?"),
_Msg("assistant", "It is 4."),
_Msg("user", "And times 3?"),
]
result = reasoning_agent._to_chat_messages(msgs)
assert result == [
{"role": "system", "content": reasoning_agent.SYSTEM_PROMPT},
{"role": "user", "content": "What is 2+2?"},
{"role": "assistant", "content": "It is 4."},
{"role": "user", "content": "And times 3?"},
]
def test_tool_and_system_input_messages_are_skipped(reasoning_agent):
"""Only user/assistant turns are threaded; tool/system input messages are
dropped so the request stays a clean conversation."""
msgs = [
_Msg("system", "ignored input system msg"),
_Msg("user", "hi"),
_Msg("tool", "tool result"),
_Msg("assistant", "hello"),
]
result = reasoning_agent._to_chat_messages(msgs)
assert result == [
{"role": "system", "content": reasoning_agent.SYSTEM_PROMPT},
{"role": "user", "content": "hi"},
{"role": "assistant", "content": "hello"},
]
def test_empty_input_preserves_empty_user_turn(reasoning_agent):
"""No user/assistant turns → ``[{system}, {user: ""}]`` (prior behaviour)."""
assert reasoning_agent._to_chat_messages([]) == [
{"role": "system", "content": reasoning_agent.SYSTEM_PROMPT},
{"role": "user", "content": ""},
]
# Input with only a tool message also falls back to the empty user turn.
assert reasoning_agent._to_chat_messages([_Msg("tool", "x")]) == [
{"role": "system", "content": reasoning_agent.SYSTEM_PROMPT},
{"role": "user", "content": ""},
]
def test_multimodal_content_is_coerced_to_joined_text(reasoning_agent):
"""List (multimodal) content joins its text parts — same coercion the old
`_extract_user_input` applied."""
msgs = [_Msg("user", [{"text": "part1 "}, {"text": "part2"}])]
result = reasoning_agent._to_chat_messages(msgs)
assert result[1] == {"role": "user", "content": "part1 part2"}
def test_none_content_coerces_to_empty_string(reasoning_agent):
"""None content (e.g. an assistant turn carrying only tool calls) coerces
to an empty string rather than the literal ``None``."""
assert reasoning_agent._coerce_content(None) == ""
msgs = [_Msg("user", "q"), _Msg("assistant", None)]
result = reasoning_agent._to_chat_messages(msgs)
assert result[2] == {"role": "assistant", "content": ""}