tests: add test_forward_message

Author: Forbidden-A

tests/hikari/impl/test_rest.py

@@ -2130,9 +2130,7 @@ class StubResponse:
                 await rest_client._request(route)
 
     @hikari_test_helpers.timeout()
-    async def test_request_when_status_in_retry_codes_will_retry_until_exhausted(
-        self, rest_client, exit_exception
-    ):
+    async def test_request_when_status_in_retry_codes_will_retry_until_exhausted(self, rest_client, exit_exception):
         class StubResponse:
             status = http.HTTPStatus.INTERNAL_SERVER_ERROR
 
@@ -2936,6 +2934,23 @@ async def test_create_voice_message(self, rest_client):
         rest_client._request.assert_awaited_once_with(expected_route, form_builder=mock_form)
         rest_client._entity_factory.deserialize_message.assert_called_once_with({"message_id": 123})
 
+    async def test_forward_message(self, rest_client):
+        rest_client._request = mock.AsyncMock(return_value={"message_id": 1239})
+        expected_route = routes.POST_CHANNEL_MESSAGES.compile(channel=1234)
+        m = await rest_client.forward_message(channel_to=1234, message=123, channel_from=12345)
+        assert m is rest_client._entity_factory.deserialize_message.return_value
+        rest_client._request.assert_awaited_once_with(
+            expected_route,
+            json={
+                "message_reference": {
+                    "message_id": "123",
+                    "channel_id": "12345",
+                    "type": message_models.MessageReferenceType.FORWARD,
+                }
+            },
+        )
+        rest_client._entity_factory.deserialize_message.assert_called_once_with({"message_id": 1239})
+
     async def test_create_voice_message_no_flags(self, rest_client):
         rest_client._request = mock.AsyncMock(return_value={"message_id": 123})
         returned = await rest_client.create_voice_message(