def test_get_next_line_number_two_invoices():
"""get the number for the next invoice line"""
invoice_1 = InvoiceFactory()
InvoiceLineFactory(invoice=invoice_1, line_number=1)
InvoiceLineFactory(invoice=invoice_1, line_number=2)
invoice_2 = InvoiceFactory()
InvoiceLineFactory(invoice=invoice_2, line_number=1)
assert 3 == invoice_1.get_next_line_number()
assert 2 == invoice_2.get_next_line_number()
def test_get_next_line_number_fill_gap():
"""get the number for the next invoice line"""
invoice = InvoiceFactory()
InvoiceLineFactory(invoice=invoice, line_number=1)
InvoiceLineFactory(invoice=invoice, line_number=2)
InvoiceLineFactory(invoice=invoice, line_number=4)
assert 3 == invoice.get_next_line_number()
def test_get_first_line_number():
"""get the number for the first invoice line"""
invoice = InvoiceFactory()
assert 1 == invoice.get_next_line_number()
