billing: Do not require a Stripe account to store Customer discounts.

corporate/lib/stripe.py

@@ -163,7 +163,7 @@ def stripe_get_customer(stripe_customer_id: str) -> stripe.Customer:
     return stripe.Customer.retrieve(stripe_customer_id, expand=["default_source"])
 
 @catch_stripe_errors
-def do_create_customer(user: UserProfile, stripe_token: Optional[str]=None) -> Customer:
+def do_create_stripe_customer(user: UserProfile, stripe_token: Optional[str]=None) -> Customer:
     realm = user.realm
     # We could do a better job of handling race conditions here, but if two
     # people from a realm try to upgrade at exactly the same time, the main
@@ -183,7 +183,8 @@ def do_create_customer(user: UserProfile, stripe_token: Optional[str]=None) -> C
             RealmAuditLog.objects.create(
                 realm=user.realm, acting_user=user, event_type=RealmAuditLog.STRIPE_CARD_CHANGED,
                 event_time=event_time)
-        customer = Customer.objects.create(realm=realm, stripe_customer_id=stripe_customer.id)
+        customer, created = Customer.objects.update_or_create(realm=realm, defaults={
+            'stripe_customer_id': stripe_customer.id})
         user.is_billing_admin = True
         user.save(update_fields=["is_billing_admin"])
     return customer
@@ -221,8 +222,8 @@ def add_plan_renewal_to_license_ledger_if_needed(plan: CustomerPlan, event_time:
 def update_or_create_stripe_customer(user: UserProfile, stripe_token: Optional[str]=None) -> Customer:
     realm = user.realm
     customer = Customer.objects.filter(realm=realm).first()
-    if customer is None:
-        return do_create_customer(user, stripe_token=stripe_token)
+    if customer is None or customer.stripe_customer_id is None:
+        return do_create_stripe_customer(user, stripe_token=stripe_token)
     if stripe_token is not None:
         do_replace_payment_source(user, stripe_token)
     return customer
@@ -442,12 +443,8 @@ def invoice_plans_as_needed(event_time: datetime) -> None:
     for plan in CustomerPlan.objects.filter(next_invoice_date__lte=event_time):
         invoice_plan(plan, event_time)
 
-def attach_discount_to_realm(user: UserProfile, discount: Decimal) -> None:
-    customer = Customer.objects.filter(realm=user.realm).first()
-    if customer is None:
-        customer = do_create_customer(user)
-    customer.default_discount = discount
-    customer.save()
+def attach_discount_to_realm(realm: Realm, discount: Decimal) -> None:
+    Customer.objects.update_or_create(realm=realm, defaults={'default_discount': discount})
 
 def process_downgrade(user: UserProfile) -> None:  # nocoverage
     pass

corporate/migrations/0006_nullable_stripe_customer_id.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.18 on 2019-01-29 01:46
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('corporate', '0005_customerplan_invoicing'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='customer',
+            name='stripe_customer_id',
+            field=models.CharField(max_length=255, null=True, unique=True),
+        ),
+    ]

corporate/models.py

@@ -9,7 +9,7 @@ from zerver.models import Realm, RealmAuditLog
 
 class Customer(models.Model):
     realm = models.OneToOneField(Realm, on_delete=CASCADE)  # type: Realm
-    stripe_customer_id = models.CharField(max_length=255, unique=True)  # type: str
+    stripe_customer_id = models.CharField(max_length=255, null=True, unique=True)  # type: str
     # Deprecated .. delete once everyone is migrated to new billing system
     has_billing_relationship = models.BooleanField(default=False)  # type: bool
     # A percentage, like 85.

corporate/tests/test_stripe.py

@@ -26,7 +26,7 @@ from zerver.models import Realm, UserProfile, get_realm, RealmAuditLog
 from corporate.lib.stripe import catch_stripe_errors, attach_discount_to_realm, \
     get_seat_count, sign_string, unsign_string, \
     BillingError, StripeCardError, StripeConnectionError, stripe_get_customer, \
-    DEFAULT_INVOICE_DAYS_UNTIL_DUE, MIN_INVOICED_LICENSES, do_create_customer, \
+    DEFAULT_INVOICE_DAYS_UNTIL_DUE, MIN_INVOICED_LICENSES, do_create_stripe_customer, \
     add_months, next_month, next_renewal_date, renewal_amount, \
     compute_plan_parameters, update_or_create_stripe_customer, \
     process_initial_upgrade, add_plan_renewal_to_license_ledger_if_needed, \
@@ -747,7 +747,7 @@ class StripeTest(StripeTestCase):
         # If you pay by invoice, your payment method should be
         # "Billed by invoice", even if you have a card on file
         # user = self.example_user("hamlet")
-        # do_create_customer(user, stripe_create_token().id)
+        # do_create_stripe_customer(user, stripe_create_token().id)
         # self.login(user.email)
         # self.upgrade(invoice=True)
         # stripe_customer = stripe_get_customer(Customer.objects.get(realm=user.realm).stripe_customer_id)
@@ -761,18 +761,32 @@ class StripeTest(StripeTestCase):
     def test_attach_discount_to_realm(self, *mocks: Mock) -> None:
         # Attach discount before Stripe customer exists
         user = self.example_user('hamlet')
-        attach_discount_to_realm(user, Decimal(85))
+        attach_discount_to_realm(user.realm, Decimal(85))
         self.login(user.email)
         # Check that the discount appears in page_params
         self.assert_in_success_response(['85'], self.client_get("/upgrade/"))
         # Check that the customer was charged the discounted amount
-        # TODO
-        # Check upcoming invoice reflects the discount
-        # TODO
+        self.upgrade()
+        stripe_customer_id = Customer.objects.values_list('stripe_customer_id', flat=True).first()
+        self.assertEqual(1200 * self.seat_count,
+                         [charge for charge in stripe.Charge.list(customer=stripe_customer_id)][0].amount)
+        stripe_invoice = [invoice for invoice in stripe.Invoice.list(customer=stripe_customer_id)][0]
+        self.assertEqual([1200 * self.seat_count, -1200 * self.seat_count],
+                         [item.amount for item in stripe_invoice.lines])
+        # Check CustomerPlan reflects the discount
+        plan = CustomerPlan.objects.get(price_per_license=1200, discount=Decimal(85))
+
         # Attach discount to existing Stripe customer
-        attach_discount_to_realm(user, Decimal(25))
-        # Check upcoming invoice reflects the new discount
-        # TODO
+        plan.status = CustomerPlan.ENDED
+        plan.save(update_fields=['status'])
+        attach_discount_to_realm(user.realm, Decimal(25))
+        process_initial_upgrade(user, self.seat_count, True, CustomerPlan.ANNUAL, stripe_create_token().id)
+        self.assertEqual(6000 * self.seat_count,
+                         [charge for charge in stripe.Charge.list(customer=stripe_customer_id)][0].amount)
+        stripe_invoice = [invoice for invoice in stripe.Invoice.list(customer=stripe_customer_id)][0]
+        self.assertEqual([6000 * self.seat_count, -6000 * self.seat_count],
+                         [item.amount for item in stripe_invoice.lines])
+        plan = CustomerPlan.objects.get(price_per_license=6000, discount=Decimal(25))
 
     @mock_stripe()
     def test_replace_payment_source(self, *mocks: Mock) -> None:
@@ -923,7 +937,7 @@ class BillingHelpersTest(ZulipTestCase):
     def test_update_or_create_stripe_customer_logic(self) -> None:
         user = self.example_user('hamlet')
         # No existing Customer object
-        with patch('corporate.lib.stripe.do_create_customer', return_value='returned') as mocked1:
+        with patch('corporate.lib.stripe.do_create_stripe_customer', return_value='returned') as mocked1:
             returned = update_or_create_stripe_customer(user, stripe_token='token')
         mocked1.assert_called()
         self.assertEqual(returned, 'returned')