PayPal: Perform full refund if amount=None

CHANGELOG.rst

@@ -13,6 +13,7 @@ v3.0.0
 - Added support for Python 3.11, Django 4.1 and Django 4.2.
 - Stripe backends now supports webhooks
 - New :ref:`webhook settings <webhooks>`
+- PayPal backends now perform a full refund if ``amount=None``.
 
 v2.0.0
 ------

payments/paypal/__init__.py

@@ -310,15 +310,19 @@ def release(self, payment):
         self.post(payment, url)
 
     def refund(self, payment, amount=None):
-        if amount is None:
-            amount = payment.captured_amount
-        amount_data = self.get_amount_data(payment, amount)
-        refund_data = {"amount": amount_data}
+        refund_data = {}
+        if amount is not None:
+            refund_data["amount"] = self.get_amount_data(payment, amount)
         links = self._get_links(payment)
         url = links["refund"]["href"]
-        self.post(payment, url, data=refund_data)
+        response = self.post(payment, url, data=refund_data)
         payment.change_status(PaymentStatus.REFUNDED)
-        return amount
+        if response["amount"]["currency"] != payment.currency:
+            raise NotImplementedError(
+                f"refund's currency other than {payment.currency} not supported yet: "
+                f"{response['amount']['currency']}"
+            )
+        return Decimal(response["amount"]["total"])
 
 
 class PaypalCardProvider(PaypalProvider):

payments/paypal/test_paypal.py

@@ -129,17 +129,53 @@ def test_provider_handles_captured_payment(self, mocked_post):
         self.assertEqual(self.payment.status, PaymentStatus.CONFIRMED)
 
     @patch("requests.post")
-    def test_provider_refunds_payment(self, mocked_post):
+    def test_provider_refunds_payment_fully(self, mocked_post):
         data = MagicMock()
-        data.return_value = {
-            "token_type": "test_token_type",
-            "access_token": "test_access_token",
-        }
+        data.side_effect = [
+            {
+                "token_type": "test_token_type",
+                "access_token": "test_access_token",
+            },
+            {"amount": {"total": "220.00", "currency": "USD"}},
+        ]
         post = MagicMock()
         post.json = data
         post.status_code = 200
         mocked_post.return_value = post
         self.provider.refund(self.payment)
+        mocked_post.assert_called_with(
+            "http://refund.com",
+            headers={
+                "Content-Type": "application/json",
+                "Authorization": "test_token_type test_access_token",
+            },
+            data="{}",
+        )
+        self.assertEqual(self.payment.status, PaymentStatus.REFUNDED)
+
+    @patch("requests.post")
+    def test_provider_refunds_payment_partially(self, mocked_post):
+        data = MagicMock()
+        data.side_effect = [
+            {
+                "token_type": "test_token_type",
+                "access_token": "test_access_token",
+            },
+            {"amount": {"total": "1.00", "currency": "USD"}},
+        ]
+        post = MagicMock()
+        post.json = data
+        post.status_code = 200
+        mocked_post.return_value = post
+        self.provider.refund(self.payment, amount=Decimal(1))
+        mocked_post.assert_called_with(
+            "http://refund.com",
+            headers={
+                "Content-Type": "application/json",
+                "Authorization": "test_token_type test_access_token",
+            },
+            data='{"amount": {"currency": "USD", "total": "1.00"}}',
+        )
         self.assertEqual(self.payment.status, PaymentStatus.REFUNDED)
 
     @patch("requests.post")