Fix unicode error when sending confirmation email in shopping cart

Wrap send email operation in try/except to avoid rolling back the transaction once a user has paid.

lms/djangoapps/shoppingcart/models.py

@@ -481,10 +481,18 @@ class Order(models.Model):
             log.exception('Exception at creating pdf file.')
             pdf_file = None
 
+        try:
             self.send_confirmation_emails(
                 orderitems, self.order_type == OrderTypes.BUSINESS,
                 csv_file, pdf_file, site_name, courses_info
             )
+        except Exception:  # pylint: disable=broad-except
+            # Catch all exceptions here, since the Django view implicitly
+            # wraps this in a transaction.  If the order completes successfully,
+            # we don't want to roll back just because we couldn't send
+            # the confirmation email.
+            log.exception('Error occurred while sending payment confirmation email')
+
         self._emit_order_event('Completed Order', orderitems)
 
     def refund(self):
@@ -1460,7 +1468,9 @@ class CertificateItem(OrderItem):
             "If you haven't verified your identity yet, please start the verification process ({verification_url})."
         ).format(verification_url=verification_url)
 
-        return "{verification_reminder} {refund_reminder}".format(
+        # Need this to be unicode in case the reminder strings
+        # have been translated and contain non-ASCII unicode
+        return u"{verification_reminder} {refund_reminder}".format(
             verification_reminder=verification_reminder,
             refund_reminder=refund_reminder
         )

lms/djangoapps/shoppingcart/tests/test_models.py

@@ -375,6 +375,34 @@ class OrderTest(ModuleStoreTestCase):
             cart.generate_receipt_instructions()
             mock_gen_inst.assert_called_with()
 
+    def test_confirmation_email_error(self):
+        CourseMode.objects.create(
+            course_id=self.course_key,
+            mode_slug="verified",
+            mode_display_name="Verified",
+            min_price=self.cost
+        )
+
+        cart = Order.get_cart_for_user(self.user)
+        CertificateItem.add_to_order(cart, self.course_key, self.cost, 'verified')
+
+        # Simulate an error when sending the confirmation
+        # email.  This should NOT raise an exception.
+        # If it does, then the implicit view-level
+        # transaction could cause a roll-back, effectively
+        # reversing order fulfillment.
+        with patch.object(mail.message.EmailMessage, 'send') as mock_send:
+            mock_send.side_effect = Exception("Kaboom!")
+            cart.purchase()
+
+        # Verify that the purchase completed successfully
+        self.assertEqual(cart.status, 'purchased')
+
+        # Verify that the user is enrolled as "verified"
+        mode, is_active = CourseEnrollment.enrollment_mode_for_user(self.user, self.course_key)
+        self.assertTrue(is_active)
+        self.assertEqual(mode, 'verified')
+
 
 class OrderItemTest(TestCase):
     def setUp(self):