Adds CreditNote, CreditNoteController, related models, and tests.

registrasion/controllers/credit_note.py

@@ -0,0 +1,51 @@
+from django.db import transaction
+
+from registrasion import models as rego
+
+
+class CreditNoteController(object):
+
+    def __init__(self, credit_note):
+        self.credit_note = credit_note
+
+    @classmethod
+    def generate_from_invoice(cls, invoice, value):
+        ''' Generates a credit note of the specified value and pays it against
+        the given invoice. You need to call InvoiceController.update_status()
+        to set the status correctly, if appropriate. '''
+
+        credit_note = rego.CreditNote.objects.create(
+            invoice=invoice,
+            amount=0-value,  # Credit notes start off as a payment against inv.
+            reference="ONE MOMENT",
+        )
+        credit_note.reference = "Generated credit note %d" % credit_note.id
+        credit_note.save()
+
+        return cls(credit_note)
+
+    @transaction.atomic
+    def apply_to_invoice(self, invoice):
+        ''' Applies the total value of this credit note to the specified
+        invoice. If this credit note overpays the invoice, a new credit note
+        containing the residual value will be created.
+
+        Raises ValidationError if the given invoice is not allowed to be
+        paid.
+        '''
+
+        from invoice import InvoiceController  # Circular imports bleh.
+        inv = InvoiceController(invoice)
+        inv.validate_allowed_to_pay()
+
+        # Apply payment to invoice
+        rego.CreditNoteApplication.objects.create(
+            parent=self.credit_note,
+            invoice=invoice,
+            amount=self.credit_note.value,
+            reference="Applied credit note #%d" % self.credit_note.id,
+        )
+
+        inv.update_status()
+
+    # TODO: Add administration fee generator.

registrasion/controllers/invoice.py

@@ -8,6 +8,7 @@ from django.utils import timezone
 from registrasion import models as rego
 
 from cart import CartController
+from credit_note import CreditNoteController
 
 
 class InvoiceController(object):
@@ -189,6 +190,12 @@ class InvoiceController(object):
             if remainder <= 0:
                 # Invoice no longer has amount owing
                 self._mark_paid()
+
+                if remainder < 0:
+                    CreditNoteController.generate_from_invoice(
+                        self.invoice,
+                        0 - remainder,
+                    )
             elif total_paid == 0 and num_payments > 0:
                 # Invoice has multiple payments totalling zero
                 self._mark_void()
@@ -247,30 +254,31 @@ class InvoiceController(object):
 
     def void(self):
         ''' Voids the invoice if it is valid to do so. '''
-        if self.invoice.status == rego.Invoice.STATUS_PAID:
-            raise ValidationError("Paid invoices cannot be voided, "
-                                  "only refunded.")
+        if self.total_payments() > 0:
+            raise ValidationError("Invoices with payments must be refunded.")
+        elif self.invoice.is_refunded:
+            raise ValidationError("Refunded invoices may not be voided.")
         self._mark_void()
 
     @transaction.atomic
-    def refund(self, reference, amount):
-        ''' Refunds the invoice by the given amount.
+    def refund(self):
+        ''' Refunds the invoice by generating a CreditNote for the value of
+        all of the payments against the cart.
 
         The invoice is marked as refunded, and the underlying cart is marked
         as released.
 
-        TODO: replace with credit notes work instead.
         '''
 
         if self.invoice.is_void:
             raise ValidationError("Void invoices cannot be refunded")
 
-        # Adds a payment
-        # TODO: replace by creating a credit note instead
-        rego.ManualPayment.objects.create(
-            invoice=self.invoice,
-            reference=reference,
-            amount=0 - amount,
-        )
+        # Raises a credit note fot the value of the invoice.
+        amount = self.total_payments()
 
+        if amount == 0:
+            self.void()
+            return
+
+        CreditNoteController.generate_from_invoice(self.invoice, amount)
         self.update_status()

registrasion/migrations/0018_creditnote_creditnoteapplication_creditnoterefund_squashed_0019_auto_20160410_0753.py

@@ -0,0 +1,43 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-04-10 07:54
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+import django.utils.timezone
+
+
+class Migration(migrations.Migration):
+
+    replaces = [('registrasion', '0018_creditnote_creditnoteapplication_creditnoterefund'), ('registrasion', '0019_auto_20160410_0753')]
+
+    dependencies = [
+        ('registrasion', '0017_auto_20160408_0731'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='CreditNote',
+            fields=[
+                ('paymentbase_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='registrasion.PaymentBase')),
+            ],
+            bases=('registrasion.paymentbase',),
+        ),
+        migrations.CreateModel(
+            name='CreditNoteApplication',
+            fields=[
+                ('paymentbase_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='registrasion.PaymentBase')),
+                ('parent', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to='registrasion.CreditNote')),
+            ],
+            bases=('registrasion.paymentbase',),
+        ),
+        migrations.CreateModel(
+            name='CreditNoteRefund',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('time', models.DateTimeField(default=django.utils.timezone.now)),
+                ('reference', models.CharField(max_length=255)),
+                ('parent', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to='registrasion.CreditNote')),
+            ],
+        ),
+    ]

registrasion/migrations/0019_manualcreditnoterefund_squashed_0020_auto_20160411_0256.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-04-11 02:57
+from __future__ import unicode_literals
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    replaces = [('registrasion', '0019_manualcreditnoterefund'), ('registrasion', '0020_auto_20160411_0256')]
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('registrasion', '0018_creditnote_creditnoteapplication_creditnoterefund_squashed_0019_auto_20160410_0753'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ManualCreditNoteRefund',
+            fields=[
+                ('entered_by', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+                ('creditnoterefund_ptr', models.OneToOneField(auto_created=True, default=0, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='registrasion.CreditNoteRefund')),
+            ],
+        ),
+    ]

registrasion/migrations/0020_auto_20160411_0258.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-04-11 02:58
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('registrasion', '0019_manualcreditnoterefund_squashed_0020_auto_20160411_0256'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='manualcreditnoterefund',
+            name='creditnoterefund_ptr',
+            field=models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='registrasion.CreditNoteRefund'),
+        ),
+    ]

registrasion/models.py

@@ -648,3 +648,95 @@ class PaymentBase(models.Model):
 class ManualPayment(PaymentBase):
     ''' Payments that are manually entered by staff. '''
     pass
+
+
+class CreditNote(PaymentBase):
+    ''' Credit notes represent money accounted for in the system that do not
+    belong to specific invoices. They may be paid into other invoices, or
+    cashed out as refunds.
+
+    Each CreditNote may either be used to pay towards another Invoice in the
+    system (by attaching a CreditNoteApplication), or may be marked as
+    refunded (by attaching a CreditNoteRefund).'''
+
+    @classmethod
+    def unclaimed(cls):
+        return cls.objects.filter(
+            creditnoteapplication=None,
+            creditnoterefund=None,
+        )
+
+    @property
+    def status(self):
+        if self.is_unclaimed:
+            return "Unclaimed"
+
+        if hasattr(self, 'creditnoteapplication'):
+            destination = self.creditnoteapplication.invoice.id
+            return "Applied to invoice %d" % destination
+
+        elif hasattr(self, 'creditnoterefund'):
+            reference = self.creditnoterefund.reference
+            print reference
+            return "Refunded with reference: %s" % reference
+
+        raise ValueError("This should never happen.")
+
+    @property
+    def is_unclaimed(self):
+        return not (
+            hasattr(self, 'creditnoterefund') or
+            hasattr(self, 'creditnoteapplication')
+        )
+
+    @property
+    def value(self):
+        ''' Returns the value of the credit note. Because CreditNotes are
+        implemented as PaymentBase objects internally, the amount is a
+        negative payment against an invoice. '''
+        return -self.amount
+
+
+class CleanOnSave(object):
+
+    def save(self, *a, **k):
+        self.full_clean()
+        super(CleanOnSave, self).save(*a, **k)
+
+
+class CreditNoteApplication(CleanOnSave, PaymentBase):
+    ''' Represents an application of a credit note to an Invoice. '''
+
+    def clean(self):
+        if not hasattr(self, "parent"):
+            return
+        if hasattr(self.parent, 'creditnoterefund'):
+            raise ValidationError(
+                "Cannot apply a refunded credit note to an invoice"
+            )
+
+    parent = models.OneToOneField(CreditNote)
+
+
+class CreditNoteRefund(CleanOnSave, models.Model):
+    ''' Represents a refund of a credit note to an external payment.
+    Credit notes may only be refunded in full. How those refunds are handled
+    is left as an exercise to the payment app. '''
+
+    def clean(self):
+        if not hasattr(self, "parent"):
+            return
+        if hasattr(self.parent, 'creditnoteapplication'):
+            raise ValidationError(
+                "Cannot refund a credit note that has been paid to an invoice"
+            )
+
+    parent = models.OneToOneField(CreditNote)
+    time = models.DateTimeField(default=timezone.now)
+    reference = models.CharField(max_length=255)
+
+
+class ManualCreditNoteRefund(CreditNoteRefund):
+    ''' Credit notes that are entered by a staff member. '''
+
+    entered_by = models.ForeignKey(User)

registrasion/tests/controller_helpers.py

@@ -1,4 +1,5 @@
 from registrasion.controllers.cart import CartController
+from registrasion.controllers.credit_note import CreditNoteController
 from registrasion.controllers.invoice import InvoiceController
 from registrasion import models as rego
 
@@ -47,3 +48,12 @@ class TestingInvoiceController(InvoiceController):
         )
 
         self.update_status()
+
+
+class TestingCreditNoteController(CreditNoteController):
+
+    def refund(self):
+        rego.CreditNoteRefund.objects.create(
+            parent=self.credit_note,
+            reference="Whoops."
+        )

registrasion/tests/test_invoice.py

@@ -6,6 +6,7 @@ from django.core.exceptions import ValidationError
 
 from registrasion import models as rego
 from controller_helpers import TestingCartController
+from controller_helpers import TestingCreditNoteController
 from controller_helpers import TestingInvoiceController
 
 from test_cart import RegistrationCartTestCase
@@ -187,12 +188,25 @@ class InvoiceTestCase(RegistrationCartTestCase):
 
         # Should be able to create an invoice after the product is added
         current_cart.add_to_cart(self.PROD_1, 1)
-        invoice_1 = TestingInvoiceController.for_cart(current_cart.cart)
+        invoice = TestingInvoiceController.for_cart(current_cart.cart)
 
-        invoice_1.pay("Reference", invoice_1.invoice.value)
+        invoice.pay("Reference", invoice.invoice.value)
 
         with self.assertRaises(ValidationError):
-            invoice_1.void()
+            invoice.void()
+
+    def test_cannot_void_partially_paid_invoice(self):
+        current_cart = TestingCartController.for_user(self.USER_1)
+
+        # Should be able to create an invoice after the product is added
+        current_cart.add_to_cart(self.PROD_1, 1)
+        invoice = TestingInvoiceController.for_cart(current_cart.cart)
+
+        invoice.pay("Reference", invoice.invoice.value - 1)
+        self.assertTrue(invoice.invoice.is_unpaid)
+
+        with self.assertRaises(ValidationError):
+            invoice.void()
 
     def test_cannot_generate_blank_invoice(self):
         current_cart = TestingCartController.for_user(self.USER_1)
@@ -210,9 +224,255 @@ class InvoiceTestCase(RegistrationCartTestCase):
         with self.assertRaises(ValidationError):
             invoice.validate_allowed_to_pay()
 
-    # TODO: test partially paid invoice cannot be void until payments
-    # are refunded
+    def test_overpaid_invoice_results_in_credit_note(self):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
 
-    # TODO: test overpaid invoice results in credit note
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
 
-    # TODO: test credit note generation more generally
+        # Invoice is overpaid by 1 unit
+        to_pay = invoice.invoice.value + 1
+        invoice.pay("Reference", to_pay)
+
+        # The total paid should be equal to the value of the invoice only
+        self.assertEqual(invoice.invoice.value, invoice.total_payments())
+        self.assertTrue(invoice.invoice.is_paid)
+
+        # There should be a credit note generated out of the invoice.
+        credit_notes = rego.CreditNote.objects.filter(invoice=invoice.invoice)
+        self.assertEqual(1, credit_notes.count())
+        self.assertEqual(to_pay - invoice.invoice.value, credit_notes[0].value)
+
+    def test_full_paid_invoice_does_not_generate_credit_note(self):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        # Invoice is paid evenly
+        invoice.pay("Reference", invoice.invoice.value)
+
+        # The total paid should be equal to the value of the invoice only
+        self.assertEqual(invoice.invoice.value, invoice.total_payments())
+        self.assertTrue(invoice.invoice.is_paid)
+
+        # There should be no credit notes
+        credit_notes = rego.CreditNote.objects.filter(invoice=invoice.invoice)
+        self.assertEqual(0, credit_notes.count())
+
+    def test_refund_partially_paid_invoice_generates_correct_credit_note(self):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        # Invoice is underpaid by 1 unit
+        to_pay = invoice.invoice.value - 1
+        invoice.pay("Reference", to_pay)
+        invoice.refund()
+
+        # The total paid should be zero
+        self.assertEqual(0, invoice.total_payments())
+        self.assertTrue(invoice.invoice.is_void)
+
+        # There should be a credit note generated out of the invoice.
+        credit_notes = rego.CreditNote.objects.filter(invoice=invoice.invoice)
+        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):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        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 = rego.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):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        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.
+        credit_note = rego.CreditNote.objects.get(invoice=invoice.invoice)
+        cn = TestingCreditNoteController(credit_note)
+
+        # That credit note should be in the unclaimed pile
+        self.assertEquals(1, rego.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, rego.CreditNote.unclaimed().count())
+
+    def test_apply_credit_note_generates_new_credit_note_if_overpaying(self):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 2)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        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.
+        credit_note = rego.CreditNote.objects.get(invoice=invoice.invoice)
+        cn = TestingCreditNoteController(credit_note)
+
+        self.assertEquals(1, rego.CreditNote.unclaimed().count())
+
+        # Create a new cart (of half value of inv 1) and get 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)
+
+        # We generated a new credit note, and spent the old one,
+        # unclaimed should still be 1.
+        self.assertEquals(1, rego.CreditNote.unclaimed().count())
+
+        credit_note2 = rego.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):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        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.
+        credit_note = rego.CreditNote.objects.get(invoice=invoice.invoice)
+        cn = TestingCreditNoteController(credit_note)
+
+        # Create a new cart with invoice, pay it
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice_2 = TestingInvoiceController.for_cart(self.reget(cart.cart))
+        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)
+
+        # 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))
+        invoice_2.void()
+        # Cannot pay void invoice
+        with self.assertRaises(ValidationError):
+            cn.apply_to_invoice(invoice_2.invoice)
+
+    def test_cannot_apply_a_refunded_credit_note(self):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        to_pay = invoice.invoice.value
+        invoice.pay("Reference", to_pay)
+        self.assertTrue(invoice.invoice.is_paid)
+
+        invoice.refund()
+
+        self.assertEquals(1, rego.CreditNote.unclaimed().count())
+
+        credit_note = rego.CreditNote.objects.get(invoice=invoice.invoice)
+
+        cn = TestingCreditNoteController(credit_note)
+        cn.refund()
+
+        # Refunding a credit note should mark it as claimed
+        self.assertEquals(0, rego.CreditNote.unclaimed().count())
+
+        # 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))
+
+        # 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):
+        cart = TestingCartController.for_user(self.USER_1)
+        cart.add_to_cart(self.PROD_1, 1)
+
+        invoice = TestingInvoiceController.for_cart(self.reget(cart.cart))
+
+        to_pay = invoice.invoice.value
+        invoice.pay("Reference", to_pay)
+        self.assertTrue(invoice.invoice.is_paid)
+
+        invoice.refund()
+
+        self.assertEquals(1, rego.CreditNote.unclaimed().count())
+
+        credit_note = rego.CreditNote.objects.get(invoice=invoice.invoice)
+
+        cn = TestingCreditNoteController(credit_note)
+
+        # 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))
+        cn.apply_to_invoice(invoice_2.invoice)
+
+        self.assertEquals(0, rego.CreditNote.unclaimed().count())
+
+        # Cannot refund this credit note as it is already applied.
+        with self.assertRaises(ValidationError):
+            cn.refund()

registrasion/tests/test_refund.py

@@ -23,7 +23,7 @@ class RefundTestCase(RegistrationCartTestCase):
         self.assertFalse(invoice.invoice.is_refunded)
         self.assertFalse(invoice.invoice.cart.released)
 
-        invoice.refund("A Refund!", invoice.invoice.value)
+        invoice.refund()
         self.assertFalse(invoice.invoice.is_void)
         self.assertFalse(invoice.invoice.is_paid)
         self.assertTrue(invoice.invoice.is_refunded)

registrasion/tests/test_voucher.py

@@ -148,7 +148,7 @@ class VoucherTestCases(RegistrationCartTestCase):
         with self.assertRaises(ValidationError):
             current_cart.apply_voucher(voucher.code)
 
-        inv.refund("Hello!", inv.invoice.value)
+        inv.refund()
         current_cart.apply_voucher(voucher.code)
 
     def test_fix_simple_errors_does_not_remove_limited_voucher(self):