Added a __del__ method to fsIndex.

src/ZODB/fsIndex.py

@@ -86,6 +86,15 @@ class fsIndex(object):
             self._data[treekey] = tree
         tree[key[6:]] = value
 
+    def __delitem__(self, key):
+        treekey = key[:6]
+        tree = self._data.get(treekey)
+        if tree is None:
+            raise KeyError, key
+        del tree[key[6:]]
+        if not tree:
+            del self._data[treekey]
+
     def __len__(self):
         r = 0
         for tree in self._data.itervalues():

src/ZODB/tests/testfsIndex.py

@@ -26,6 +26,24 @@ class Test(unittest.TestCase):
         for i in range(200):
             self.index[p64(i * 1000)] = (i * 1000L + 1)
 
+    def test__del__(self):
+        index = self.index
+        self.assert_(p64(1000) in index)
+        self.assert_(p64(100*1000) in index)
+        
+        del self.index[p64(1000)]
+        del self.index[p64(100*1000)]
+
+        self.assert_(p64(1000) not in index)
+        self.assert_(p64(100*1000) not in index)
+
+        for key in list(self.index):
+            del index[key]
+        self.assert_(not index)
+
+        # Whitebox. Make sure empty buckets are removed
+        self.assert_(not index._data)
+
     def testInserts(self):
         index = self.index