def METHOD_NAME(self):
    """Test rejects cube with multiple realizations"""
    vel1 = self.valid.copy()
    vel1.add_aux_coord(DimCoord(1, standard_name="realization"))
    vel2 = self.valid.copy()
    vel2.add_aux_coord(DimCoord(2, standard_name="realization"))
    (invalid_3d,) = (iris.cube.CubeList([vel1, vel2])).merge()
    msg = "Cube has 3"
    with self.assertRaisesRegexp(InvalidCubeError, msg):
        check_input_coords(invalid_3d)