Merge pull request #5209 from edx/cdodge/allow-to-pass-override-cancel-URL

pass along an extra parameter to CyberSource to sepcify a callback URL i...

lms/djangoapps/shoppingcart/processors/CyberSource2.py

@@ -126,6 +126,12 @@ def verify_signatures(params):
             (missing keys, wrong types)
 
     """
+
+    # First see if the user cancelled the transaction
+    # if so, then not all parameters will be passed back so we can't yet verify signatures
+    if params.get('decision') == u'CANCEL':
+        raise CCProcessorUserCancelled()
+
     # Validate the signature to ensure that the message is from CyberSource
     # and has not been tampered with.
     signed_fields = params.get('signed_field_names', '').split(',')
@@ -272,6 +278,7 @@ def get_purchase_params(cart, callback_url=None):
 
     if callback_url is not None:
         params['override_custom_receipt_page'] = callback_url
+        params['override_custom_cancel_page'] = callback_url
 
     return params
 
@@ -461,6 +468,16 @@ def _get_processor_exception_html(exception):
                 email=payment_support_email
             )
         )
+    elif isinstance(exception, CCProcessorUserCancelled):
+        return _format_error_html(
+            _(
+                u"Sorry! Our payment processor sent us back a message saying that you have cancelled this transaction. "
+                u"The items in your shopping cart will exist for future purchase. "
+                u"If you feel that this is in error, please contact us with payment-specific questions at {email}."
+            ).format(
+                email=payment_support_email
+            )
+        )
     else:
         return _format_error_html(
             _(

lms/djangoapps/shoppingcart/processors/exceptions.py

@@ -15,3 +15,6 @@ class CCProcessorDataException(CCProcessorException):
 
 class CCProcessorWrongAmountException(CCProcessorException):
     pass
+
+class CCProcessorUserCancelled(CCProcessorException):
+    pass

lms/djangoapps/shoppingcart/processors/tests/test_CyberSource2.py

@@ -94,7 +94,8 @@ class CyberSource2Test(TestCase):
                 'unsigned_field_names',
                 'transaction_uuid',
                 'payment_method',
-                'override_custom_receipt_page'
+                'override_custom_receipt_page',
+                'override_custom_cancel_page',
             ])
         )
         self.assertEqual(params['unsigned_field_names'], '')
@@ -169,6 +170,16 @@ class CyberSource2Test(TestCase):
         self.assertFalse(result['success'])
         self.assertIn(u"badly-typed value", result['error_html'])
 
+    def test_process_user_cancelled(self):
+        # Change the payment amount to a non-decimal
+        params = self._signed_callback_params(self.order.id, self.COST, "abcd")
+        params['decision'] = u'CANCEL'
+        result = process_postpay_callback(params)
+
+        # Expect an error
+        self.assertFalse(result['success'])
+        self.assertIn(u"you have cancelled this transaction", result['error_html'])
+
     @patch.object(OrderItem, 'purchased_callback')
     def test_process_no_credit_card_digits(self, callback):
         # Use a credit card number with no digits provided