fix: added check for duplicate refund transactions (#243)

* fix: added check for duplicate refund transactions

* fix: added stripe refund signal to test file

commerce_coordinator/apps/commercetools/tasks.py

@@ -10,6 +10,7 @@
 from django.conf import settings
 
 from .clients import CommercetoolsAPIClient
+from .utils import has_full_refund_transaction
 
 logger = logging.getLogger(__name__)
 
@@ -58,6 +59,10 @@ def refund_from_stripe_task(
     client = CommercetoolsAPIClient()
     try:
         payment = client.get_payment_by_key(payment_intent_id)
+        if has_full_refund_transaction(payment):
+            logger.info(f"Stripe charge.refunded event received, but Payment with ID {payment.id} "
+                        f"already has a full refund. Skipping task to add refund transaction")
+            return None
         updated_payment = client.create_return_payment_transaction(
             payment_id=payment.id,
             payment_version=payment.version,

commerce_coordinator/apps/commercetools/tests/conftest.py

@@ -168,16 +168,38 @@ def gen_payment():
         amount_planned=4900,
         payment_method_info={},
         payment_status=PaymentState.PAID,
-        transactions=[gen_transaction()],
+        transactions=[gen_transaction(TransactionType.REFUND, 4900)],
         interface_interactions=[]
     )
 
 
-def gen_transaction() -> CTTransaction:
+def gen_payment_with_multiple_transactions(*args):
+    """
+    Generate a CTPayment object with multiple transaction records
+    """
+    transactions = []
+    for i in range(0, len(args), 2):
+        transaction = gen_transaction(args[i], args[i+1])
+        transactions.append(transaction)
+
+    return CTPayment(
+        id=uuid4_str(),
+        version=1,
+        created_at=datetime.now(),
+        last_modified_at=datetime.now(),
+        amount_planned=4900,
+        payment_method_info={},
+        payment_status=PaymentState.PAID,
+        transactions=transactions,
+        interface_interactions=[]
+    )
+
+
+def gen_transaction(transaction_type=None, amount=None) -> CTTransaction:
     return CTTransaction(
         id=uuid4_str(),
-        type=TransactionType.REFUND,
-        amount=4900,
+        type=transaction_type,
+        amount=amount,
         timestamp=datetime.now(),
         state=TransactionState.SUCCESS,
         interaction_id='ch_3P9RWsH4caH7G0X11toRGUJf'

commerce_coordinator/apps/commercetools/tests/test_tasks.py

@@ -7,13 +7,14 @@
 
 import stripe
 from commercetools import CommercetoolsError
+from commercetools.platform.models import TransactionType
 from django.test import TestCase
 
 from commerce_coordinator.apps.commercetools.tasks import (
     refund_from_stripe_task,
     update_line_item_state_on_fulfillment_completion
 )
-from commerce_coordinator.apps.commercetools.tests.conftest import gen_payment
+from commerce_coordinator.apps.commercetools.tests.conftest import gen_payment, gen_payment_with_multiple_transactions
 from commerce_coordinator.apps.commercetools.tests.constants import (
     EXAMPLE_RETURNED_ORDER_STRIPE_CLIENT_PAYLOAD,
     EXAMPLE_RETURNED_ORDER_STRIPE_SIGNAL_PAYLOAD,
@@ -121,6 +122,27 @@ def test_correct_arguments_passed(self, mock_client):
             stripe_refund=mock_stripe_refund
         )
 
+    def test_full_refund_already_exists(self, mock_client):
+        '''
+        Check if the payment already has a full refund, the task logs the
+        appropriate message and skips creating a refund transaction.
+        '''
+        mock_payment = gen_payment_with_multiple_transactions(
+            TransactionType.CHARGE, 4900,
+            TransactionType.REFUND, 4900
+        )
+        mock_payment.id = 'f988e0c5-ea44-4111-a7f2-39ecf6af9840'
+
+        mock_client.return_value.get_payment_by_key.return_value = mock_payment
+
+        with patch('commerce_coordinator.apps.commercetools.tasks.logger') as mock_logger:
+            result = refund_from_stripe_task(*self.unpack_for_uut(EXAMPLE_RETURNED_ORDER_STRIPE_SIGNAL_PAYLOAD))
+            self.assertIsNone(result)
+            mock_logger.info.assert_called_once_with(
+                f"Stripe charge.refunded event received, but Payment with ID {mock_payment.id} "
+                f"already has a full refund. Skipping task to add refund transaction"
+            )
+
     @patch('commerce_coordinator.apps.commercetools.tasks.logger')
     def test_exception_handling(self, mock_logger, mock_client):
         '''

commerce_coordinator/apps/commercetools/tests/test_utils.py

@@ -15,13 +15,19 @@
 from mock import Mock, patch
 
 from commerce_coordinator.apps.commercetools.catalog_info.edx_utils import get_edx_lms_user_name
-from commerce_coordinator.apps.commercetools.tests.conftest import gen_example_customer, gen_order, gen_payment
+from commerce_coordinator.apps.commercetools.tests.conftest import (
+    gen_example_customer,
+    gen_order,
+    gen_payment,
+    gen_payment_with_multiple_transactions
+)
 from commerce_coordinator.apps.commercetools.tests.constants import EXAMPLE_FULFILLMENT_SIGNAL_PAYLOAD
 from commerce_coordinator.apps.commercetools.utils import (
     create_zendesk_ticket,
     extract_ct_order_information_for_braze_canvas,
     extract_ct_product_information_for_braze_canvas,
     get_braze_client,
+    has_full_refund_transaction,
     has_refund_transaction,
     send_order_confirmation_email,
     send_refund_notification,
@@ -205,6 +211,24 @@ def test_has_refund_transaction_without_refund(self):
         self.assertFalse(has_refund_transaction(payment))
 
 
+class TestHasFullRefundTransaction(unittest.TestCase):
+    """
+    Tests for Has Full Refund Transaction Utils function
+    """
+
+    def test_has_full_refund_transaction_with_full_refund(self):
+        payment = gen_payment_with_multiple_transactions(TransactionType.CHARGE, 4900, TransactionType.REFUND, 4900)
+        self.assertTrue(has_full_refund_transaction(payment))
+
+    def test_has_partial_refund_transaction(self):
+        payment = gen_payment_with_multiple_transactions(TransactionType.CHARGE, 4900, TransactionType.REFUND, 2500)
+        self.assertFalse(has_full_refund_transaction(payment))
+
+    def test_has_no_refund_transaction(self):
+        payment = gen_payment_with_multiple_transactions(TransactionType.CHARGE, 4900)
+        self.assertFalse(has_full_refund_transaction(payment))
+
+
 class TestTranslateStripeRefundStatus(unittest.TestCase):
     """
     Tests for Translating Stripes Refund Status Utils class

commerce_coordinator/apps/commercetools/utils.py

@@ -139,6 +139,21 @@ def has_refund_transaction(payment: Payment):
     return False
 
 
+def has_full_refund_transaction(payment: Payment):
+    """
+    Utility to determine is CT payment has an existing 'refund' transaction for the full
+    charge amount
+    """
+    # get charge transaction and get amount then check against refund.
+    charge_amount = 0
+    for transaction in payment.transactions:
+        if transaction.type == TransactionType.CHARGE:
+            charge_amount = transaction.amount
+        if transaction.type == TransactionType.REFUND and transaction.amount == charge_amount:  # pragma no cover
+            return True
+    return False
+
+
 def translate_stripe_refund_status_to_transaction_status(stripe_refund_status: str):
     """
     Utility to translate stripe's refund object's status attribute to a valid CT transaction state

commerce_coordinator/settings/base.py

@@ -327,6 +327,9 @@ def root(*path_fragments):
     'commerce_coordinator.apps.commercetools.sub_messages.signals_dispatch.fulfill_order_returned_signal': [
         'commerce_coordinator.apps.commercetools.sub_messages.signals_delayed.fulfill_order_returned_signal',
     ],
+    'commerce_coordinator.apps.stripe.signals.payment_refunded_signal': [
+        'commerce_coordinator.apps.commercetools.signals.refund_from_stripe',
+    ],
 }
 
 # Default timeouts for requests

commerce_coordinator/settings/test.py

@@ -84,6 +84,9 @@
     'commerce_coordinator.apps.commercetools.sub_messages.signals_dispatch.fulfill_order_returned_signal': [
         'commerce_coordinator.apps.commercetools.sub_messages.signals_delayed.fulfill_order_returned_signal',
     ],
+    'commerce_coordinator.apps.stripe.signals.payment_refunded_signal': [
+        'commerce_coordinator.apps.commercetools.signals.refund_from_stripe',
+    ],
 }
 
 COMMERCETOOLS_CONFIG = {