def METHOD_NAME(self):
    """Test if bonds have been written properly: just look at number of bonds"""
    if self.types_to_write == 'all':
        simulation_bonds = np.array([1, 2, 3])  # the two bonded particles
    elif 2 in self.types_to_write:
        simulation_bonds = np.array(2)  # only this one is type 2
    np.testing.assert_allclose(
        np.shape(simulation_bonds), np.shape(self.written_bonds),
        err_msg="Bonds not written correctly by writevsf!")