| """Tests for the in-memory TTL cache in data/cache.py — the Cache class and |
| the @cached decorator, tested in isolation with no live API calls and no |
| dependency on wmata_realtime.py/weather.py. |
| """ |
|
|
| import time |
|
|
| from data.cache import Cache, cached |
|
|
|
|
| def test_get_returns_value_before_ttl_expires(): |
| cache = Cache() |
| cache.set("station", "Metro Center", ttl_seconds=5) |
|
|
| assert cache.get("station") == "Metro Center" |
|
|
|
|
| def test_get_returns_none_after_ttl_expires(): |
| cache = Cache() |
| cache.set("station", "Metro Center", ttl_seconds=0.1) |
|
|
| time.sleep(0.15) |
|
|
| assert cache.get("station") is None |
|
|
|
|
| def test_expired_entry_is_evicted_from_store(): |
| cache = Cache() |
| cache.set("station", "Metro Center", ttl_seconds=0.1) |
| time.sleep(0.15) |
|
|
| cache.get("station") |
|
|
| assert cache.stats()["size"] == 0 |
|
|
|
|
| def test_get_missing_key_returns_none(): |
| cache = Cache() |
| assert cache.get("does-not-exist") is None |
|
|
|
|
| def test_clear_removes_all_entries(): |
| cache = Cache() |
| cache.set("a", 1, ttl_seconds=5) |
| cache.set("b", 2, ttl_seconds=5) |
|
|
| cache.clear() |
|
|
| assert cache.get("a") is None |
| assert cache.get("b") is None |
| assert cache.stats()["size"] == 0 |
|
|
|
|
| def test_stats_tracks_hits_misses_and_size(): |
| cache = Cache() |
| cache.set("a", 1, ttl_seconds=5) |
|
|
| cache.get("a") |
| cache.get("a") |
| cache.get("missing") |
|
|
| stats = cache.stats() |
| assert stats["hits"] == 2 |
| assert stats["misses"] == 1 |
| assert stats["size"] == 1 |
|
|
|
|
| def test_stats_counts_expiry_as_a_miss(): |
| cache = Cache() |
| cache.set("a", 1, ttl_seconds=0.1) |
| time.sleep(0.15) |
|
|
| cache.get("a") |
|
|
| stats = cache.stats() |
| assert stats["hits"] == 0 |
| assert stats["misses"] == 1 |
|
|
|
|
| def test_cached_decorator_returns_cached_value_before_ttl_expires(): |
| calls = [] |
|
|
| @cached(ttl_seconds=5) |
| def slow_double(n): |
| calls.append(n) |
| return n * 2 |
|
|
| assert slow_double(3) == 6 |
| assert slow_double(3) == 6 |
|
|
| assert calls == [3] |
|
|
|
|
| def test_cached_decorator_recomputes_after_ttl_expires(): |
| calls = [] |
|
|
| @cached(ttl_seconds=0.1) |
| def slow_double(n): |
| calls.append(n) |
| return n * 2 |
|
|
| assert slow_double(3) == 6 |
| time.sleep(0.15) |
| assert slow_double(3) == 6 |
|
|
| assert calls == [3, 3] |
|
|
|
|
| def test_cached_decorator_uses_different_keys_for_different_args(): |
| calls = [] |
|
|
| @cached(ttl_seconds=5) |
| def slow_double(n): |
| calls.append(n) |
| return n * 2 |
|
|
| assert slow_double(3) == 6 |
| assert slow_double(4) == 8 |
| assert slow_double(3) == 6 |
| assert slow_double(4) == 8 |
|
|
| assert calls == [3, 4] |
|
|
|
|
| def test_cached_decorator_uses_different_keys_for_different_kwargs(): |
| calls = [] |
|
|
| @cached(ttl_seconds=5) |
| def get_thing(station=None): |
| calls.append(station) |
| return f"info for {station}" |
|
|
| assert get_thing(station="Metro Center") == "info for Metro Center" |
| assert get_thing(station="Union Station") == "info for Union Station" |
| assert get_thing(station="Metro Center") == "info for Metro Center" |
|
|
| assert calls == ["Metro Center", "Union Station"] |
|
|
|
|
| def test_cached_decorator_exposes_underlying_cache_for_clearing(): |
| @cached(ttl_seconds=5) |
| def slow_double(n): |
| return n * 2 |
|
|
| slow_double(3) |
| assert slow_double.cache.stats()["size"] == 1 |
|
|
| slow_double.cache.clear() |
| assert slow_double.cache.stats()["size"] == 0 |
|
|
