def METHOD_NAME(variants_vec_backends_once_rgb):
    xml = """
    <float name="alpha_u" value="0.5"/>
    <float name="alpha_v" value="0.2"/>
    """
    wi = dr.normalize(mi.ScalarVector3f(-0.5, -0.5, 0.1))
    ctx = mi.BSDFContext()
    ctx.component = 1
    sample_func, pdf_func = mi.chi2.BSDFAdapter("roughdielectric", xml, wi=wi, ctx=ctx)
    chi2 = mi.chi2.ChiSquareTest(
        domain=mi.chi2.SphericalDomain(),
        sample_func=sample_func,
        pdf_func=pdf_func,
        sample_dim=3,
        res=201
    )
    assert chi2.run()