'Don\'t leak a key when adding it to a context.'

def test_keyGetsFreed(self):

    lib = FakeLib()
    self.patch(sslverify._OpenSSLECCurve, '_getBinding', (lambda self: FakeBinding(lib=lib)))
    curve = sslverify._OpenSSLECCurve(sslverify._defaultCurveName)
    ctx = FakeContext(None)
    ctx._context = None
    curve.addECKeyToContext(ctx)
    self.assertEqual(set(), lib._createdKeys)
