'Create a LogUnit subclass object for given physical unit,
and do basic check that output is right.'

@pytest.mark.parametrize(u'lu_cls,    physical_unit', itertools.product((lu_subclasses + [u.LogUnit]), pu_sample))
def test_subclass_creation(self, lu_cls, physical_unit):

    lu1 = lu_cls(physical_unit)
    assert (lu1.physical_unit == physical_unit)
    assert (lu1.function_unit == lu1._default_function_unit)
    lu2 = lu_cls(physical_unit, function_unit=(2 * lu1._default_function_unit))
    assert (lu2.physical_unit == physical_unit)
    assert (lu2.function_unit == u.Unit((2 * lu2._default_function_unit)))
    with pytest.raises(ValueError):
        lu_cls(physical_unit, u.m)
