def test_jointree_marginals_trivial_evidence(self):
        ft = FactorTree.create_jointree(self.bn)
        ft.set_evidence({"slippery_road":"true"})
        resFactor = ft.marginals(["slippery_road"])
        np.testing.assert_array_almost_equal(resFactor.get_potential(), np.array([1.0, 0.0]))