Create function to check for long names in devices (#8364)

* Create a new function to verify that the length of a device name is
under a certain threshold.
* Refactor old code and tests to use said function.
* Verify device name length during registration of device
* Add a test for the above

Signed-off-by: Dionysis Grigoropoulos <dgrig@erethon.com>

2 files changed, 12 insertions, 1 deletions

diff --git a/tests/handlers/test_device.py b/tests/handlers/test_device.py

index 6aa322bf3a..969d44c787 100644
--- a/tests/handlers/test_device.py
+++ b/tests/handlers/test_device.py
@@ -35,6 +35,17 @@ class DeviceTestCase(unittest.HomeserverTestCase):
         # These tests assume that it starts 1000 seconds in.
         self.reactor.advance(1000)
 
+    def test_device_is_created_with_invalid_name(self):
+        self.get_failure(
+            self.handler.check_device_registered(
+                user_id="@boris:foo",
+                device_id="foo",
+                initial_device_display_name="a"
+                * (synapse.handlers.device.MAX_DEVICE_DISPLAY_NAME_LEN + 1),
+            ),
+            synapse.api.errors.SynapseError,
+        )
+
     def test_device_is_created_if_doesnt_exist(self):
         res = self.get_success(
             self.handler.check_device_registered(
diff --git a/tests/rest/admin/test_device.py b/tests/rest/admin/test_device.py

index faa7f381a9..92c9058887 100644
--- a/tests/rest/admin/test_device.py
+++ b/tests/rest/admin/test_device.py
@@ -221,7 +221,7 @@ class DeviceRestTestCase(unittest.HomeserverTestCase):
         self.render(request)
 
         self.assertEqual(400, channel.code, msg=channel.json_body)
-        self.assertEqual(Codes.UNKNOWN, channel.json_body["errcode"])
+        self.assertEqual(Codes.TOO_LARGE, channel.json_body["errcode"])
 
         # Ensure the display name was not updated.
         request, channel = self.make_request(