self.assertEqual(1, credit_notes.count())

        self.assertEqual(to_pay, credit_notes[0].value)

    def test_refund_fully_paid_invoice_generates_correct_credit_note(self):

        invoice = self._invoice_containing_prod_1(1)

        to_pay = invoice.invoice.value

        invoice.pay("Reference", to_pay)

        self.assertTrue(invoice.invoice.is_paid)

        invoice.refund()

        # The total paid should be zero

        self.assertEqual(0, invoice.total_payments())

        self.assertTrue(invoice.invoice.is_refunded)

        # There should be a credit note generated out of the invoice.

        credit_notes = commerce.CreditNote.objects.filter(

            invoice=invoice.invoice,

        )

        self.assertEqual(1, credit_notes.count())

        self.assertEqual(to_pay, credit_notes[0].value)

    def test_apply_credit_note_pays_invoice(self):

        invoice = self._invoice_containing_prod_1(1)

        to_pay = invoice.invoice.value

        invoice.pay("Reference", to_pay)

        self.assertTrue(invoice.invoice.is_paid)

        invoice.refund()

        # There should be one credit note generated out of the invoice.

        cn = self._credit_note_for_invoice(invoice.invoice)

        # That credit note should be in the unclaimed pile

        self.assertEquals(1, commerce.CreditNote.unclaimed().count())

        # Create a new (identical) cart with invoice

        cart = TestingCartController.for_user(self.USER_1)

        cart.add_to_cart(self.PROD_1, 1)

        invoice2 = TestingInvoiceController.for_cart(self.reget(cart.cart))

        cn.apply_to_invoice(invoice2.invoice)

        self.assertTrue(invoice2.invoice.is_paid)

        # That invoice should not show up as unclaimed any more

        self.assertEquals(0, commerce.CreditNote.unclaimed().count())

    def test_apply_credit_note_generates_new_credit_note_if_overpaying(self):

        invoice = self._invoice_containing_prod_1(2)

        self.assertTrue(invoice.invoice.is_paid)

        invoice.refund()

        # There should be one credit note generated out of the invoice.

        cn = self._credit_note_for_invoice(invoice.invoice)

        self.assertEquals(1, commerce.CreditNote.unclaimed().count())

        self.assertTrue(invoice2.invoice.is_paid)

        # We generated a new credit note, and spent the old one,

        # unclaimed should still be 1.

        self.assertEquals(1, commerce.CreditNote.unclaimed().count())

        credit_note2 = commerce.CreditNote.objects.get(

            invoice=invoice2.invoice,

        )

        # The new credit note should be the residual of the cost of cart 1

        # minus the cost of cart 2.

        self.assertEquals(

            invoice.invoice.value - invoice2.invoice.value,

            credit_note2.value,

        )

    def test_cannot_apply_credit_note_on_invalid_invoices(self):

        invoice = self._invoice_containing_prod_1(1)

        to_pay = invoice.invoice.value

        invoice.pay("Reference", to_pay)

        self.assertTrue(invoice.invoice.is_paid)

        invoice.refund()

        # There should be one credit note generated out of the invoice.

        cn = self._credit_note_for_invoice(invoice.invoice)

        # Create a new cart with invoice, pay it

        invoice_2 = self._invoice_containing_prod_1(1)

        invoice_2.pay("LOL", invoice_2.invoice.value)

        # Cannot pay paid invoice

        with self.assertRaises(ValidationError):

            cn.apply_to_invoice(invoice_2.invoice)

        invoice_2.refund()

        # Cannot pay refunded invoice

        with self.assertRaises(ValidationError):

            cn.apply_to_invoice(invoice_2.invoice)

        invoice_2 = TestingInvoiceController.for_cart(self.reget(cart.cart))

        # Cannot pay with this credit note.

        with self.assertRaises(ValidationError):

            cn.apply_to_invoice(invoice_2.invoice)

    def test_cannot_refund_an_applied_credit_note(self):

        invoice = self._invoice_containing_prod_1(1)

        to_pay = invoice.invoice.value

        invoice.pay("Reference", to_pay)

        self.assertTrue(invoice.invoice.is_paid)

        invoice.refund()

        self.assertEquals(1, commerce.CreditNote.unclaimed().count())

        cn = self._credit_note_for_invoice(invoice.invoice)

        # Create a new cart with invoice

        cart = TestingCartController.for_user(self.USER_1)

        cart.add_to_cart(self.PROD_1, 1)

        invoice_2 = TestingInvoiceController.for_cart(self.reget(cart.cart))

        self.assertEquals(0, commerce.CreditNote.unclaimed().count())

        # Cannot refund this credit note as it is already applied.

        with self.assertRaises(ValidationError):

            cn.refund()

    def test_money_into_void_invoice_generates_credit_note(self):

        invoice = self._invoice_containing_prod_1(1)

        invoice.void()

        val = invoice.invoice.value

        invoice.pay("Paying into the void.", val, pre_validate=False)

        cn = self._credit_note_for_invoice(invoice.invoice)

        self.assertEqual(val, cn.credit_note.value)

    def test_money_into_refunded_invoice_generates_credit_note(self):

        invoice = self._invoice_containing_prod_1(1)

        val = invoice.invoice.value

        invoice.pay("Paying the first time.", val)

        invoice.refund()

        invoice.pay("Paying the first time.", val)

        invoice.pay("Paying into the void.", val, pre_validate=False)

        cn = self._credit_note_for_invoice(invoice.invoice)

        self.assertEqual(val, cn.credit_note.value)

    def test_invoice_with_credit_note_applied_is_refunded(self):

        ''' Invoices with partial payments should void when cart is updated.

        Test for issue #64 -- applying a credit note to an invoice

        means that invoice cannot be voided, and new invoices cannot be

        created. '''

        invoice = self._invoice_containing_prod_1(1)

        # Now get a credit note

        invoice.pay("Lol", invoice.invoice.value)

        invoice.refund()

        cn = self._credit_note_for_invoice(invoice.invoice)

        # Create a cart of higher value than the credit note

        cart = TestingCartController.for_user(self.USER_1)

        cart.add_to_cart(self.PROD_1, 2)

        invoice = TestingInvoiceController.for_cart(cart.cart)

        # Adding to cart will mean that the old invoice for this cart

        # will be invalidated. A new invoice should be generated.

        cart.add_to_cart(self.PROD_1, 1)

        invoice = TestingInvoiceController.for_id(invoice.invoice.id)

        invoice2 = TestingInvoiceController.for_cart(cart.cart)

        cn2 = self._credit_note_for_invoice(invoice.invoice)

        invoice._refresh()

        # The first invoice should be refunded

        self.assertEquals(

            commerce.Invoice.STATUS_VOID,

            invoice.invoice.status,

        )

        # Both credit notes should be for the same amount

        self.assertEquals(

            cn.credit_note.value,

            cn2.credit_note.value,

        )

    def test_creating_invoice_automatically_applies_credit_note(self):

        ''' Single credit note is automatically applied to new invoices. '''