Remove remaining references held by test suite, so that xdel test pas…

…ses.

IPython/core/tests/test_magic.py

@@ -404,11 +404,26 @@ def test_xdel(self):
                "        self.monitor.append(1)\n"
                "a = A()\n")
         self.mktmp(src)
+        # %run creates some hidden references...
         _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
+
+        # Check that a's __del__ method has been called.
         nt.assert_equal(monitor, [1])
 
 def doctest_who():

IPython/testing/globalipapp.py

@@ -132,6 +132,15 @@ def update(self,other):
         # correct for that ourselves, to ensure consitency with the 'real'
         # 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 get_ipython():