Allow a choice of LRU behaviour for Cache() by using LruCache() or OrderedDict()

tests/storage/test__base.py

@@ -69,6 +69,28 @@ class CacheTestCase(unittest.TestCase):
         cache.get(2)
         cache.get(3)
 
+    def test_eviction_lru(self):
+        cache = Cache("test", max_entries=2, lru=True)
+
+        cache.prefill(1, "one")
+        cache.prefill(2, "two")
+
+        # Now access 1 again, thus causing 2 to be least-recently used
+        cache.get(1)
+
+        cache.prefill(3, "three")
+
+        failed = False
+        try:
+            cache.get(2)
+        except KeyError:
+            failed = True
+
+        self.assertTrue(failed)
+
+        cache.get(1)
+        cache.get(3)
+
 
 class CacheDecoratorTestCase(unittest.TestCase):