def test_deprecatedUnjellyingInstanceAtom(self):
        """
        Unjellying the instance atom is deprecated with 15.0.0.
        """
        jelly.unjelly(
            ["instance",
             ["class", "twisted.spread.test.test_jelly.A"],
             ["dictionary"]])
        warnings = self.flushWarnings()
        self.assertEqual(len(warnings), 1)
        self.assertEqual(
            warnings[0]['message'],
            "Unjelly support for the instance atom is deprecated since "
            "Twisted 15.0.0.  Upgrade peer for modern instance support.")
        self.assertEqual(
            warnings[0]['category'],
            DeprecationWarning)

        Unjellying the instance atom is deprecated with 15.0.0.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/spread/test/test_jelly.py