def METHOD_NAME(self):
    """
    Tests that phase function returns appropriate values.
    """
    for mod in self.allmods:
        if "calc_Phi" in mod.__dict__:
            with RedirectStreams(stdout=self.dev_null):
                obj = mod()
            betas = np.linspace(0.0, np.pi, 100) * u.rad
            Phi = obj.calc_Phi(betas)
            self.assertTrue(
                len(Phi) == len(betas),
                (
                    "length of phase function values returned does not match input "
                    f"phase angles for {mod.__name__}"
                ),
            )
            self.assertTrue(
                np.all(np.isfinite(Phi)),
                "calc_Phi returned infinite value for %s" % mod.__name__,
            )
            self.assertTrue(
                np.all(Phi <= 1.0),
                "calc_Phi returned value > 1 for %s" % mod.__name__,
            )
            self.assertTrue(
                np.all(Phi >= 0.0),
                "calc_Phi returned negative value for %s" % mod.__name__,
            )