def test_creation(self):
il = InvoiceLine()
il.quantity = 11
il.price = 2
il.item_name = 'test'
il.tax_percent = 0.21
il.tax_category = "S"
assert il.is_valid()
def test_invalid_price(self):
il = InvoiceLine()
with pytest.raises(ValueError):
il.price = "dasdas"