fix(mail): rate-limit direct and fallback sends

tests/test_rate_limit.py

@@ -0,0 +1,80 @@
+from __future__ import annotations
+
+import unittest
+from unittest.mock import patch
+
+from redis.exceptions import RedisError
+
+from govoplan_mail.backend.sending import rate_limit
+
+
+class RateLimitTests(unittest.TestCase):
+    def setUp(self) -> None:
+        rate_limit._local_next_allowed.clear()
+
+    def test_local_fallback_waits_between_sends(self) -> None:
+        now = [100.0]
+        sleeps: list[float] = []
+
+        def fake_time() -> float:
+            return now[0]
+
+        def fake_sleep(seconds: float) -> None:
+            sleeps.append(seconds)
+            now[0] += seconds
+
+        with (
+            patch.object(rate_limit, "_distributed_rate_limit_enabled", return_value=False),
+            patch.object(rate_limit.time, "time", fake_time),
+            patch.object(rate_limit.time, "sleep", fake_sleep),
+        ):
+            first = rate_limit.wait_for_rate_limit(key="tenant:t:campaign:c", messages_per_minute=4)
+            second = rate_limit.wait_for_rate_limit(key="tenant:t:campaign:c", messages_per_minute=4)
+
+        self.assertEqual(first.waited_seconds, 0.0)
+        self.assertEqual(second.waited_seconds, 15.0)
+        self.assertEqual(sleeps, [15.0])
+
+    def test_disabled_rate_limit_does_not_reserve_local_slot(self) -> None:
+        now = [100.0]
+        sleeps: list[float] = []
+
+        with (
+            patch.object(rate_limit, "_distributed_rate_limit_enabled", return_value=False),
+            patch.object(rate_limit.time, "time", lambda: now[0]),
+            patch.object(rate_limit.time, "sleep", lambda seconds: sleeps.append(seconds)),
+        ):
+            disabled = rate_limit.wait_for_rate_limit(key="k", messages_per_minute=4, enabled=False)
+            enabled = rate_limit.wait_for_rate_limit(key="k", messages_per_minute=4)
+
+        self.assertEqual(disabled.waited_seconds, 0.0)
+        self.assertEqual(enabled.waited_seconds, 0.0)
+        self.assertEqual(sleeps, [])
+
+    def test_redis_failure_falls_back_to_local_wait(self) -> None:
+        now = [100.0]
+        sleeps: list[float] = []
+
+        def fail_redis_client():
+            raise RedisError("redis unavailable")
+
+        def fake_sleep(seconds: float) -> None:
+            sleeps.append(seconds)
+            now[0] += seconds
+
+        with (
+            patch.object(rate_limit, "_distributed_rate_limit_enabled", return_value=True),
+            patch.object(rate_limit, "_redis_client", fail_redis_client),
+            patch.object(rate_limit.time, "time", lambda: now[0]),
+            patch.object(rate_limit.time, "sleep", fake_sleep),
+        ):
+            first = rate_limit.wait_for_rate_limit(key="k", messages_per_minute=60)
+            second = rate_limit.wait_for_rate_limit(key="k", messages_per_minute=60)
+
+        self.assertEqual(first.waited_seconds, 0.0)
+        self.assertEqual(second.waited_seconds, 1.0)
+        self.assertEqual(sleeps, [1.0])
+
+
+if __name__ == "__main__":
+    unittest.main()