def METHOD_NAME(self):
    """
    Test case of clean images (coeff_clean and noise_var=0)
    while using a non Identity CTF.
    This case may come up when a developer switches between
    clean and dirty images.
    """
    # Calculate CWF coefficients using Cov2D base class
    mean_cov2d = self.cov2d.get_mean(
        self.coeff, ctf_fb=self.ctf_fb, ctf_idx=self.ctf_idx
    )
    covar_cov2d = self.cov2d.get_covar(
        self.coeff,
        ctf_fb=self.ctf_fb,
        ctf_idx=self.ctf_idx,
        noise_var=self.noise_var,
        make_psd=True,
    )
    coeff_cov2d = self.cov2d.get_cwf_coeffs(
        self.coeff,
        self.ctf_fb,
        self.ctf_idx,
        mean_coeff=mean_cov2d,
        covar_coeff=covar_cov2d,
        noise_var=0,
    )
    # Calculate CWF coefficients using Batched Cov2D class
    mean_bcov2d = self.bcov2d.get_mean()
    covar_bcov2d = self.bcov2d.get_covar(noise_var=self.noise_var, make_psd=True)
    coeff_bcov2d = self.bcov2d.get_cwf_coeffs(
        self.coeff,
        self.ctf_fb,
        self.ctf_idx,
        mean_bcov2d,
        covar_bcov2d,
        noise_var=0,
    )
    self.assertTrue(
        self.blk_diag_allclose(
            coeff_cov2d,
            coeff_bcov2d,
            atol=utest_tolerance(self.dtype),
        )
    )