Refactor duplicated code

tests/test_search.py

@@ -8,6 +8,7 @@ import pytest
 from knowledge_search_mcp.main import (
     GoogleCloudFileStorage,
     GoogleCloudVectorSearch,
+    LRUCache,
     SourceNamespace,
 )
 
@@ -19,14 +20,15 @@ class TestGoogleCloudFileStorage:
         """Test storage initialization."""
         storage = GoogleCloudFileStorage(bucket="test-bucket")
         assert storage.bucket_name == "test-bucket"
-        assert storage._cache == {}
+        assert isinstance(storage._cache, LRUCache)
+        assert storage._cache.max_size == 100
 
     @pytest.mark.asyncio
     async def test_cache_hit(self):
         """Test that cached files are returned without fetching."""
         storage = GoogleCloudFileStorage(bucket="test-bucket")
         test_content = b"cached content"
-        storage._cache["test.md"] = test_content
+        storage._cache.put("test.md", test_content)
 
         result = await storage.async_get_file_stream("test.md")
 
@@ -48,7 +50,7 @@ class TestGoogleCloudFileStorage:
             result = await storage.async_get_file_stream("test.md")
 
             assert result.read() == test_content
-            assert storage._cache["test.md"] == test_content
+            assert storage._cache.get("test.md") == test_content
 
 
 class TestGoogleCloudVectorSearch: