fix: Handle payment errors during user flow (#2951)

Co-authored-by: Matthew Elwell <matthew.elwell@flagsmith.com>

api/organisations/chargebee/chargebee.py

@@ -12,6 +12,7 @@
 from ..subscriptions.exceptions import (
     CannotCancelChargebeeSubscription,
     UpgradeSeatsError,
+    UpgradeSeatsPaymentFailure,
 )
 from .cache import ChargebeeCache
 from .constants import ADDITIONAL_SEAT_ADDON_ID
@@ -21,6 +22,15 @@
 
 logger = logging.getLogger(__name__)
 
+CHARGEBEE_PAYMENT_ERROR_CODES = [
+    "payment_processing_failed",
+    "payment_method_verification_failed",
+    "payment_method_not_present",
+    "payment_gateway_currency_incompatible",
+    "payment_intent_invalid",
+    "payment_intent_invalid_amount",
+]
+
 
 def get_subscription_data_from_hosted_page(hosted_page_id):
     hosted_page = get_hosted_page(hosted_page_id)
@@ -155,7 +165,6 @@ def add_single_seat(subscription_id: str):
     try:
         subscription = chargebee.Subscription.retrieve(subscription_id).subscription
         addons = subscription.addons or []
-
         current_seats = next(
             (
                 addon.quantity
@@ -177,6 +186,15 @@ def add_single_seat(subscription_id: str):
         )
 
     except ChargebeeAPIError as e:
+        api_error_code = e.json_obj["api_error_code"]
+        if api_error_code in CHARGEBEE_PAYMENT_ERROR_CODES:
+            logger.warning(
+                f"Payment declined ({api_error_code}) during additional "
+                f"seat upgrade to a CB subscription for subscription_id "
+                f"{subscription_id}"
+            )
+            raise UpgradeSeatsPaymentFailure() from e
+
         msg = (
             "Failed to add additional seat to CB subscription for subscription id: %s"
             % subscription_id

api/organisations/invites/tests/test_views.py

@@ -1,16 +1,20 @@
 import json
+import typing
 from datetime import timedelta
 
 import pytest
+from chargebee import APIError as ChargebeeAPIError
 from django.conf import settings
 from django.urls import reverse
 from django.utils import timezone
+from pytest_django.fixtures import SettingsWrapper
 from pytest_lazyfixture import lazy_fixture
+from pytest_mock.plugin import MockerFixture
 from rest_framework import status
-from rest_framework.test import APITestCase
+from rest_framework.test import APIClient, APITestCase
 
 from organisations.invites.models import Invite, InviteLink
-from organisations.models import Organisation, OrganisationRole
+from organisations.models import Organisation, OrganisationRole, Subscription
 from users.models import FFAdminUser
 
 
@@ -282,7 +286,6 @@ def test_join_organisation_returns_400_if_exceeds_plan_limit(
     settings.ENABLE_CHARGEBEE = True
     settings.AUTO_SEAT_UPGRADE_PLANS = ["scale-up"]
     url = reverse(url, args=[invite_object.hash])
-
     # When
     response = test_user_client.post(url)
 
@@ -294,6 +297,61 @@ def test_join_organisation_returns_400_if_exceeds_plan_limit(
     )
 
 
+@pytest.mark.parametrize(
+    "invite_object, url",
+    [
+        (lazy_fixture("invite"), "api-v1:users:user-join-organisation"),
+        (lazy_fixture("invite_link"), "api-v1:users:user-join-organisation-link"),
+    ],
+)
+def test_join_organisation_returns_400_if_payment_fails(
+    test_user_client: APIClient,
+    organisation: Organisation,
+    admin_user: FFAdminUser,
+    invite_object: typing.Union[Invite, InviteLink],
+    url: str,
+    subscription: Subscription,
+    settings: SettingsWrapper,
+    mocker: MockerFixture,
+):
+    # Given
+    settings.ENABLE_CHARGEBEE = True
+    settings.AUTO_SEAT_UPGRADE_PLANS = ["scale-up"]
+
+    url = reverse(url, args=[invite_object.hash])
+
+    subscription.plan = "scale-up"
+    subscription.subscription_id = "chargemepls"
+    subscription.save()
+
+    mocked_cb_subscription = mocker.MagicMock(addons=[])
+
+    mocked_chargebee = mocker.patch("organisations.chargebee.chargebee.chargebee")
+    mocked_chargebee.Subscription.retrieve.return_value = mocked_cb_subscription
+
+    chargebee_response_data = {
+        "message": "Subscription cannot be created as the payment collection failed. Gateway Error: Card declined.",
+        "type": "payment",
+        "api_error_code": "payment_processing_failed",
+        "param": "item_id",
+        "error_code": "DeprecatedField",
+    }
+
+    mocked_chargebee.Subscription.update.side_effect = ChargebeeAPIError(
+        http_code=400, json_obj=chargebee_response_data
+    )
+
+    # When
+    response = test_user_client.post(url)
+
+    # Then
+    assert response.status_code == status.HTTP_400_BAD_REQUEST
+    assert (
+        response.json()["detail"]
+        == "Joining the organisation has failed due to a payment issue. Please contact your organisation's admin."
+    )
+
+
 def test_join_organisation_from_link_returns_403_if_invite_links_disabled(
     test_user_client, organisation, invite_link, settings
 ):

api/organisations/subscriptions/exceptions.py

@@ -14,6 +14,14 @@ class UpgradeSeatsError(APIException):
     default_detail = "Failed to upgrade seats in Chargebee"
 
 
+class UpgradeSeatsPaymentFailure(APIException):
+    status_code = 400
+    default_detail = (
+        "Joining the organisation has failed due to a payment issue. "
+        "Please contact your organisation's admin."
+    )
+
+
 class SubscriptionDoesNotSupportSeatUpgrade(APIException):
     status_code = 400
     default_detail = "Please Upgrade your plan to add additional seats/users"

api/tests/unit/organisations/chargebee/test_unit_chargebee_chargebee.py

@@ -518,17 +518,19 @@ def test_add_single_seat_without_existing_addon(mocker):
 
 def test_add_single_seat_throws_upgrade_seats_error_error_if_api_error(mocker, caplog):
     # Given
-
-    # Chargebee's APIError requires additional arguments to instantiate it so instead
-    # we mock it with our own exception here to test that it is caught correctly
-    class MockException(Exception):
-        pass
-
     mocked_chargebee = mocker.patch("organisations.chargebee.chargebee.chargebee")
 
-    mocker.patch("organisations.chargebee.chargebee.ChargebeeAPIError", MockException)
-
-    mocked_chargebee.Subscription.update.side_effect = MockException
+    # Typical non-payment related error from Chargebee.
+    chargebee_response_data = {
+        "message": "82sa2Sqa5 not found",
+        "type": "invalid_request",
+        "api_error_code": "resource_not_found",
+        "param": "item_id",
+        "error_code": "DeprecatedField",
+    }
+    mocked_chargebee.Subscription.update.side_effect = APIError(
+        http_code=404, json_obj=chargebee_response_data
+    )
 
     # Let's create a (mocked) subscription object
     subscription_id = "sub-id"