Cleanup LRUCache, fix bug, add unit tests (pytest).

cista/lrucache.py

@@ -2,16 +2,43 @@ from time import monotonic
 
 
 class LRUCache:
+    """
+    LRUCache is a least-recently-used (LRU) cache with expiry time.
+
+    Attributes:
+        open (callable): Function to open a new handle.
+        capacity (int): Max number of items in the cache.
+        maxage (float): Max age for items in cache in seconds.
+        cache (list): Internal list storing the cache items.
+    """
     def __init__(self, open: callable, *, capacity: int, maxage: float):
+        """
+        Initialize LRUCache.
+
+        Args:
+            open (callable): Function to open a new handle.
+            capacity (int): Maximum capacity of the cache.
+            maxage (float): Max age for items in cache in seconds.
+        """
         self.open = open
         self.capacity = capacity
         self.maxage = maxage
         self.cache = []  # Each item is a tuple: (key, handle, timestamp), recent items first
 
     def __contains__(self, key):
+        """Check if key is in cache."""
         return any(rec[0] == key for rec in self.cache)
 
     def __getitem__(self, key):
+        """
+        Retrieve an item by its key.
+
+        Args:
+            key: The key to retrieve.
+
+        Returns:
+            The corresponding item's handle.
+        """
         # Take from cache or open a new one
         for i, (k, f, ts) in enumerate(self.cache):
             if k == key:
@@ -20,15 +47,22 @@ class LRUCache:
         else:
             f = self.open(key)
         # Add/restore to end of cache
-        self.cache.append((key, f, monotonic()))
+        self.cache.insert(0, (key, f, monotonic()))
         self.expire_items()
+        print(self.cache)
         return f
 
     def expire_items(self):
+        """
+        Expire items that are either too old or exceed cache capacity.
+        """
         ts = monotonic() - self.maxage
         while len(self.cache) > self.capacity or self.cache and self.cache[-1][2] < ts:
             self.cache.pop()[1].close()
 
     def close(self):
+        """
+        Close the cache and remove all items.
+        """
         self.capacity = 0
         self.expire_items()

tests/test_lrucache.py

@@ -0,0 +1,55 @@
+import pytest
+from unittest.mock import Mock
+from time import sleep
+from cista.lrucache import LRUCache  # Replace with actual import
+
+def mock_open(key):
+    mock = Mock()
+    mock.close = Mock()
+    mock.content = f"content-{key}"
+    return mock
+
+def test_contains():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=10)
+    assert "key1" not in cache
+    cache["key1"]
+    assert "key1" in cache
+
+def test_getitem():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=10)
+    assert cache["key1"].content == "content-key1"
+
+def test_capacity():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=10)
+    item1 = cache["key1"]
+    item2 = cache["key2"]
+    cache["key3"]
+    assert "key1" not in cache
+    item1.close.assert_called()
+
+def test_expiry():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=0.1)
+    item = cache["key1"]
+    sleep(0.2)  # Wait for expiration
+    cache.expire_items()
+    assert "key1" not in cache
+    item.close.assert_called()
+
+def test_close():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=10)
+    item = cache["key1"]
+    cache.close()
+    assert "key1" not in cache
+    item.close.assert_called()
+
+def test_lru_mechanism():
+    cache = LRUCache(open=mock_open, capacity=2, maxage=10)
+    item1 = cache["key1"]
+    item2 = cache["key2"]
+    cache["key1"]  # Make key1 recently used
+    cache["key3"]  # This should remove key2
+    assert "key1" in cache
+    assert "key2" not in cache
+    assert "key3" in cache
+    item2.close.assert_called()
+    item1.close.assert_not_called()