Fix #200: Handle __missing__ not storing cache items.

4 files changed, 38 insertions, 20 deletions

diff --git a/cachetools/lfu.py b/cachetools/lfu.py
index 17c2b9d..894a326 100644
--- a/cachetools/lfu.py
+++ b/cachetools/lfu.py
@@ -12,7 +12,8 @@ class LFUCache(Cache):
 
     def __getitem__(self, key, cache_getitem=Cache.__getitem__):
         value = cache_getitem(self, key)
-        self.__counter[key] -= 1
+        if key in self:  # __missing__ may not store item
+            self.__counter[key] -= 1
         return value
 
     def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
diff --git a/cachetools/lru.py b/cachetools/lru.py
index 2508e5d..33749d1 100644
--- a/cachetools/lru.py
+++ b/cachetools/lru.py
@@ -12,7 +12,8 @@ class LRUCache(Cache):
 
     def __getitem__(self, key, cache_getitem=Cache.__getitem__):
         value = cache_getitem(self, key)
-        self.__update(key)
+        if key in self:  # __missing__ may not store item
+            self.__update(key)
         return value
 
     def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
diff --git a/cachetools/mru.py b/cachetools/mru.py
index 92b8e76..41e2aa1 100644
--- a/cachetools/mru.py
+++ b/cachetools/mru.py
@@ -12,7 +12,8 @@ class MRUCache(Cache):
 
     def __getitem__(self, key, cache_getitem=Cache.__getitem__):
         value = cache_getitem(self, key)
-        self.__update(key)
+        if key in self:  # __missing__ may not store item
+            self.__update(key)
         return value
 
     def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
diff --git a/tests/__init__.py b/tests/__init__.py
index 82f85ef..70a0f03 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -120,7 +120,14 @@ class CacheTestMixin(object):
         self.assertIsNone(exception.__cause__)
         self.assertTrue(exception.__suppress_context__)
 
-    def _test_missing(self, cache):
+    def test_missing(self):
+        class DefaultCache(self.Cache):
+            def __missing__(self, key):
+                self[key] = key
+                return key
+
+        cache = DefaultCache(maxsize=2)
+
         self.assertEqual(0, cache.currsize)
         self.assertEqual(2, cache.maxsize)
         self.assertEqual(0, len(cache))
@@ -172,30 +179,38 @@ class CacheTestMixin(object):
         self.assertTrue(1 in cache or 2 in cache)
         self.assertTrue(1 not in cache or 2 not in cache)
 
-    def _test_missing_getsizeof(self, cache):
+    def test_missing_getsizeof(self):
+        class DefaultCache(self.Cache):
+            def __missing__(self, key):
+                try:
+                    self[key] = key
+                except ValueError:
+                    pass  # not stored
+                return key
+
+        cache = DefaultCache(maxsize=2, getsizeof=lambda x: x)
+
         self.assertEqual(0, cache.currsize)
         self.assertEqual(2, cache.maxsize)
+
         self.assertEqual(1, cache[1])
+        self.assertEqual(1, len(cache))
+        self.assertEqual(1, cache.currsize)
         self.assertIn(1, cache)
+
         self.assertEqual(2, cache[2])
+        self.assertEqual(1, len(cache))
+        self.assertEqual(2, cache.currsize)
         self.assertNotIn(1, cache)
         self.assertIn(2, cache)
-        self.assertEqual(3, cache[3])
-        self.assertNotIn(1, cache)
-        self.assertIn(2, cache)
-        self.assertNotIn(3, cache)
 
-    def test_missing_subclass(self):
-        class Cache(self.Cache):
-            def __missing__(self, key):
-                try:
-                    self[key] = key
-                except ValueError:
-                    pass
-                return key
-
-        self._test_missing(Cache(maxsize=2))
-        self._test_missing_getsizeof(Cache(maxsize=2, getsizeof=lambda x: x))
+        self.assertEqual(3, cache[3])  # not stored
+        self.assertEqual(1, len(cache))
+        self.assertEqual(2, cache.currsize)
+        self.assertEqual(1, cache[1])
+        self.assertEqual(1, len(cache))
+        self.assertEqual(1, cache.currsize)
+        self.assertEqual((1, 1), cache.popitem())
 
     def _test_getsizeof(self, cache):
         self.assertEqual(0, cache.currsize)