100 lines
3.1 KiB
Python
100 lines
3.1 KiB
Python
|
"""限流计数后端契约测试（不连 Redis）。
|
||
|
|
|
||
|
|
锁定两条必须成立的语义：
|
||
|
|
|
||
|
|
1. 正常路径：窗口内计数递增，并把"剩余窗口秒数"作为 `Retry-After` 的来源返回；
|
||
|
|
键首次创建（`TTL` 为 -1）时补一次过期，避免出现永不过期的脏计数键。
|
||
|
|
2. **降级路径**：Redis 构造失败或命令失败一律返回 `None`（=无法判定），由调用方放行。
|
||
|
|
限流是保护措施，不能因为 Redis 故障把正常请求全部拒掉——这条如果回归，故障时
|
||
|
|
整个平台会 429 全灭。
|
||
|
|
"""
|
||
|
|
|
||
|
|
from typing import Any
|
||
|
|
|
||
|
|
from app.infrastructure.rate_limiter import RedisCounterBackend
|
||
|
|
|
||
|
|
|
||
|
|
class FakePipeline:
|
||
|
|
def __init__(self, client: "FakeRedis") -> None:
|
||
|
|
self._client = client
|
||
|
|
|
||
|
|
async def __aenter__(self) -> "FakePipeline":
|
||
|
|
return self
|
||
|
|
|
||
|
|
async def __aexit__(self, *exc: object) -> bool:
|
||
|
|
return False
|
||
|
|
|
||
|
|
def incr(self, key: str) -> "FakePipeline":
|
||
|
|
self._client.incr_keys.append(key)
|
||
|
|
return self
|
||
|
|
|
||
|
|
def ttl(self, key: str) -> "FakePipeline":
|
||
|
|
self._client.ttl_keys.append(key)
|
||
|
|
return self
|
||
|
|
|
||
|
|
async def execute(self) -> list[Any]:
|
||
|
|
if self._client.fail:
|
||
|
|
raise ConnectionError("redis unavailable")
|
||
|
|
self._client.count += 1
|
||
|
|
return [self._client.count, self._client.ttl_value]
|
||
|
|
|
||
|
|
|
||
|
|
class FakeRedis:
|
||
|
|
def __init__(self, *, fail: bool = False, ttl_value: int = 42) -> None:
|
||
|
|
self.fail = fail
|
||
|
|
self.ttl_value = ttl_value
|
||
|
|
self.count = 0
|
||
|
|
self.incr_keys: list[str] = []
|
||
|
|
self.ttl_keys: list[str] = []
|
||
|
|
self.expired: list[tuple[str, int]] = []
|
||
|
|
|
||
|
|
def pipeline(self, transaction: bool = False) -> FakePipeline:
|
||
|
|
del transaction
|
||
|
|
return FakePipeline(self)
|
||
|
|
|
||
|
|
async def expire(self, key: str, seconds: int) -> bool:
|
||
|
|
self.expired.append((key, seconds))
|
||
|
|
return True
|
||
|
|
|
||
|
|
|
||
|
|
def backend(client: Any) -> RedisCounterBackend:
|
||
|
|
return RedisCounterBackend(
|
||
|
|
"redis://unused", connect_timeout_seconds=0.1, client_factory=lambda: client
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
async def test_first_request_counts_one_and_reports_remaining_window() -> None:
|
||
|
|
client = FakeRedis(ttl_value=42)
|
||
|
|
|
||
|
|
result = await backend(client).increment("k", 60)
|
||
|
|
|
||
|
|
assert result == (1, 42)
|
||
|
|
assert client.incr_keys == ["k"]
|
||
|
|
|
||
|
|
|
||
|
|
async def test_missing_ttl_is_repaired_with_window_expiry() -> None:
|
||
|
|
"""`TTL` 为 -1 说明键没有过期时间：必须补一次，否则计数永远不归零。"""
|
||
|
|
client = FakeRedis(ttl_value=-1)
|
||
|
|
|
||
|
|
result = await backend(client).increment("k", 60)
|
||
|
|
|
||
|
|
assert result == (1, 60)
|
||
|
|
assert client.expired == [("k", 60)]
|
||
|
|
|
||
|
|
|
||
|
|
async def test_redis_command_failure_degrades_to_unknown() -> None:
|
||
|
|
client = FakeRedis(fail=True)
|
||
|
|
|
||
|
|
assert await backend(client).increment("k", 60) is None
|
||
|
|
|
||
|
|
|
||
|
|
async def test_client_construction_failure_degrades_to_unknown() -> None:
|
||
|
|
def exploding_factory() -> Any:
|
||
|
|
raise RuntimeError("redis not installed")
|
||
|
|
|
||
|
|
instance = RedisCounterBackend(
|
||
|
|
"redis://unused", connect_timeout_seconds=0.1, client_factory=exploding_factory
|
||
|
|
)
|
||
|
|
|
||
|
|
assert await instance.increment("k", 60) is None
|