diff --git a/tests/test_cache_system.py b/tests/test_cache_system.py
index fd1f812c..436c2d58 100644
--- a/tests/test_cache_system.py
+++ b/tests/test_cache_system.py
@@ -490,96 +490,6 @@ def test_file_cache_uses_default_ttl_when_omitted(monkeypatch):
     assert AsyncFileCache().ttl == 7 * 24 * 3600
 
 
-def test_memory_backend_supports_per_key_ttl():
-    """
-    同一 region 的 key 应按各自 TTL 过期，不受首个 key 的 TTL 影响。
-    """
-    region = "per_key_ttl"
-    cache = MemoryBackend()
-    cache.set("short", "short-value", ttl=10, region=region)
-    cache.set("long", "long-value", ttl=20, region=region)
-    region_cache = MemoryBackend._region_caches[cache.get_region(region)]
-    started_at = region_cache.timer()
-
-    region_cache.expire(time=started_at + 11)
-
-    assert cache.get("short", region=region) is None
-    assert cache.get("long", region=region) == "long-value"
-    assert list(cache.items(region=region)) == [("long", "long-value")]
-
-
-def test_memory_backend_resets_ttl_when_key_is_rewritten():
-    """
-    重写已有 key 时应从重写时刻按新 TTL 重新计算过期时间。
-    """
-    region = "rewrite_per_key_ttl"
-    cache = MemoryBackend()
-    cache.set("key", "old", ttl=10, region=region)
-    region_cache = MemoryBackend._region_caches[cache.get_region(region)]
-    started_at = region_cache.timer()
-
-    cache.set("key", "new", ttl=20, region=region)
-    region_cache.expire(time=started_at + 11)
-
-    assert cache.get("key", region=region) == "new"
-
-    region_cache.expire(time=started_at + 21)
-
-    assert cache.get("key", region=region) is None
-
-
-def test_memory_backend_instances_share_region_with_per_key_ttl():
-    """
-    多个 backend 仍共享 region 数据，但每次写入的显式 TTL 应独立生效。
-    """
-    region = "shared_per_key_ttl"
-    first = MemoryBackend()
-    second = MemoryBackend()
-    first.set("first", "first-value", ttl=10, region=region)
-    second.set("second", "second-value", ttl=20, region=region)
-    region_cache = MemoryBackend._region_caches[first.get_region(region)]
-    started_at = region_cache.timer()
-
-    region_cache.expire(time=started_at + 11)
-
-    assert second.get("first", region=region) is None
-    assert first.get("second", region=region) == "second-value"
-
-
-def test_async_memory_backend_supports_per_key_ttl():
-    """
-    异步代理路径应与同步 backend 共享 region，并保留每个 key 的 TTL。
-    """
-    async def run_test():
-        region = "async_per_key_ttl"
-        sync_cache = MemoryBackend()
-        async_cache = AsyncMemoryBackend()
-        await async_cache.set("short", "short-value", ttl=10, region=region)
-        sync_cache.set("long", "long-value", ttl=20, region=region)
-        region_cache = MemoryBackend._region_caches[sync_cache.get_region(region)]
-        started_at = region_cache.timer()
-        region_cache.expire(time=started_at + 11)
-
-        assert await async_cache.get("short", region=region) is None
-        assert await async_cache.get("long", region=region) == "long-value"
-
-    asyncio.run(run_test())
-
-
-def test_memory_lru_backend_keeps_capacity_eviction_behavior():
-    """
-    per-key TTL 改造不应影响 LRU region 的容量淘汰行为。
-    """
-    region = "memory_lru"
-    cache = MemoryBackend(cache_type="lru", maxsize=2)
-    cache.set("first", 1, region=region)
-    cache.set("second", 2, region=region)
-    cache.set("third", 3, region=region)
-
-    assert cache.get("first", region=region) is None
-    assert list(cache.items(region=region)) == [("second", 2), ("third", 3)]
-
-
 def test_redis_original_key_decodes_quoted_key():
     """
     Redis items 返回的 key 应还原为原始缓存 key，确保带特殊字符的 key 可继续删除。