Add a test for device list updates of local users coming down /sync (#305)

* Add a test for device list updates of local users coming down /sync

* Switch to /whoami endpoint for device ID discovery

Co-authored-by: Kegan Dougal <[email protected]>

Author: anoadragon453

tests/csapi/device_lists_test.go

@@ -0,0 +1,66 @@
+package csapi_tests
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/matrix-org/complement/internal/b"
+	"github.com/matrix-org/complement/internal/client"
+
+	"github.com/tidwall/gjson"
+)
+
+// TestLocalUsersReceiveDeviceListUpdates tests that users on the same
+// homeserver receive device list updates from other local users, as
+// long as they share a room.
+func TestLocalUsersReceiveDeviceListUpdates(t *testing.T) {
+	// Create a homeserver with two users that share a room
+	deployment := Deploy(t, b.BlueprintOneToOneRoom)
+	defer deployment.Destroy(t)
+
+	// Get a reference to the already logged-in CS API clients for each user
+	alice := deployment.Client(t, "hs1", "@alice:hs1")
+	bob := deployment.Client(t, "hs1", "@bob:hs1")
+
+	// Deduce alice's device ID
+	resp := alice.MustDoFunc(
+		t,
+		"GET",
+		[]string{"_matrix", "client", "v3", "account", "whoami"},
+	)
+	responseBodyBytes := client.ParseJSON(t, resp)
+	aliceDeviceID := gjson.GetBytes(responseBodyBytes, "device_id").Str
+
+	// Bob performs an initial sync
+	_, bobNextBatch := bob.MustSync(t, client.SyncReq{})
+
+	// Alice then updates their device list by renaming their current device
+	alice.MustDoFunc(
+		t,
+		"PUT",
+		[]string{"_matrix", "client", "v3", "devices", aliceDeviceID},
+		client.WithJSONBody(
+			t,
+			map[string]interface{}{
+				"display_name": "A New Device Name",
+			},
+		),
+	)
+
+	// Check that Bob received a device list update from Alice
+	bob.MustSyncUntil(
+		t,
+		client.SyncReq{
+			Since: bobNextBatch,
+		}, func(clientUserID string, topLevelSyncJSON gjson.Result) error {
+			// Ensure that Bob sees that Alice has updated their device list
+			usersWithChangedDeviceListsArray := topLevelSyncJSON.Get("device_lists.changed").Array()
+			for _, userID := range usersWithChangedDeviceListsArray {
+				if userID.Str == alice.UserID {
+					return nil
+				}
+			}
+			return fmt.Errorf("missing device list update for Alice")
+		},
+	)
+}