Remove object references kept by the test suite in a better way.

IPython/core/tests/test_magic.py

@@ -408,20 +408,11 b' class TestXdel(tt.TempFileMixin):'
         _ip.magic("run %s" % self.fname)
         # ... as does the displayhook.
         _ip.run_cell("a")
-        a = _ip.user_ns["a"]
+        
         monitor = _ip.user_ns["A"].monitor
         nt.assert_equal(monitor, [])
-        _ip.magic("xdel a")
         
-        # The testing framework stores extra references - we kill those
-        # here. See IPython.testing.globalipapp.ipnsdict.
-        _ip.user_ns.killrefs(a)
-        del a
-        
-        # For some reason the test doesn't pass if this is removed.
-        # TODO: Work out why, and improve the test.
-        f = sys._getframe()
-        print f.f_locals
+        _ip.magic("xdel a")
         
         # Check that a's __del__ method has been called.
         nt.assert_equal(monitor, [1])

IPython/testing/globalipapp.py

@@ -133,14 +133,15 b' class ipnsdict(dict):'
         # ipython.
         self['__builtins__'] = __builtin__
         
-    def killrefs(self, obj):
-        """For part of the testing, we need to be able to remove
-        references to an object, which would otherwise be kept in
-        _savedict."""
-        todel = [n for n, o in self._savedict.iteritems() if o is obj]
-        for n in todel:
-            del self._savedict[n]
-        
+    def __delitem__(self, key):
+        """Part of the test suite checks that we can release all
+        references to an object. So we need to make sure that we're not
+        keeping a reference in _savedict."""
+        dict.__delitem__(self, key)
+        try:
+            del self._savedict[key]
+        except KeyError:
+            pass
 
 
 def get_ipython():