Support MSC2033: Device ID on whoami

changelog.d/9918.feature

@@ -0,0 +1 @@
+Add support for [MSC2033](https://github.com/matrix-org/matrix-doc/pull/2033): `device_id` on `/account/whoami`.

synapse/rest/client/v2_alpha/account.py

@@ -884,7 +884,10 @@ def __init__(self, hs):
     async def on_GET(self, request):
         requester = await self.auth.get_user_by_req(request)
 
-        return 200, {"user_id": requester.user.to_string()}
+        return 200, {
+            "user_id": requester.user.to_string(),
+            "device_id": requester.device_id,
+        }
 
 
 def register_servlets(hs, http_server):

tests/rest/client/v2_alpha/test_account.py

@@ -397,7 +397,7 @@ def test_deactivate_account(self):
         self.assertTrue(self.get_success(store.get_user_deactivated_status(user_id)))
 
         # Check that this access token has been invalidated.
-        channel = self.make_request("GET", "account/whoami")
+        channel = self.make_request("GET", "account/whoami", access_token=tok)
         self.assertEqual(channel.code, 401)
 
     def test_pending_invites(self):
@@ -458,6 +458,29 @@ def deactivate(self, user_id, tok):
         self.assertEqual(channel.code, 200)
 
 
+class WhoamiTestCase(unittest.HomeserverTestCase):
+
+    servlets = [
+        synapse.rest.admin.register_servlets_for_client_rest_resource,
+        login.register_servlets,
+        account.register_servlets,
+        register.register_servlets,
+    ]
+
+    def test_GET_whoami(self):
+        device_id = "wouldgohere"
+        user_id = self.register_user("kermit", "test")
+        tok = self.login("kermit", "test", device_id=device_id)
+
+        whoami = self.whoami(tok)
+        self.assertEqual(whoami, {"user_id": user_id, "device_id": device_id})
+
+    def whoami(self, tok):
+        channel = self.make_request("GET", "account/whoami", {}, access_token=tok)
+        self.assertEqual(channel.code, 200)
+        return channel.json_body
+
+
 class ThreepidEmailRestTestCase(unittest.HomeserverTestCase):
 
     servlets = [