def METHOD_NAME(red_int_generator):
    calib = 0.1
    red_int_generator.set_diffraction_calibration(calibration=calib)
    elements = ["Cu"]
    fracs = [1]
    assert red_int_generator.background_fit is None
    assert red_int_generator.normalisation is None
    red_int_generator.fit_atomic_scattering(elements=elements, fracs=fracs)
    assert red_int_generator.background_fit.data.shape == (2, 2, 10)
    assert red_int_generator.normalisation.data.shape == (2, 2, 10)