Use public endpoint in stripe mock (#1505)

Co-authored-by: helenye-stripe <[email protected]>

Author: mbroshi-stripe

tests/api_resources/test_list_object.py

@@ -51,15 +51,15 @@ def test_create(self, http_client_mock, list_object):
         assert res.foo == "bar"
         assert res.stripe_account == "acct_123"
 
-    def test_create_maintains_list_properties(
+    def test_retrieve_maintains_list_properties(
         self, http_client_mock, list_object
     ):
         # Testing with real requests because our mock makes it impossible to
         # test otherwise
         charge = stripe.Charge.retrieve("ch_123", api_key="sk_test_custom")
-        res = charge.refunds.create(amount=123)
+        res = charge.refunds.retrieve("re_abc")
         http_client_mock.assert_requested(
-            "post", path="/v1/charges/ch_123/refunds", post_data="amount=123"
+            "get", path="/v1/charges/ch_123/refunds/re_abc"
         )
         assert res.api_key == "sk_test_custom"