def METHOD_NAME(self):
    df = self.bidf.copy(deep=True) * 100  # copy df
    df["SiO2"] += 50  # modify df
    dfval = df["SiO2"].values[0]
    out = df.pyrocomp.renormalise()  # renorm
    self.assertTrue(df["SiO2"].values[0] == dfval)  # check original hasn't changed
    self.assertTrue((np.allclose(out.sum(axis=1), 100.0)))  # check output