diff --git a/src/tests/utils/mocks/MockKwinClient.ts b/src/tests/utils/mocks/MockKwinClient.ts
index 59412c3..a93130a 100644
--- a/src/tests/utils/mocks/MockKwinClient.ts
+++ b/src/tests/utils/mocks/MockKwinClient.ts
@@ -4,7 +4,7 @@ class MockKwinClient {
     private static readonly borderThickness = 10;
 
     public readonly shadeable: boolean = false;
-    public readonly caption = "App";
+    public caption = "App";
     public minSize: Readonly<QmlSize> = new MockQmlSize(0, 0);
     public readonly transient: boolean;
     public readonly move: boolean = false;
@@ -197,4 +197,8 @@ class MockKwinClient {
     public getFrameGeometryCopy() {
         return this._frameGeometry.clone();
     }
+
+    public toString() {
+        return `MockKwinClient("${this.caption}")`;
+    }
 }
diff --git a/src/tests/utils/mocks/MockWorkspace.ts b/src/tests/utils/mocks/MockWorkspace.ts
index ea2357f..441f4b5 100644
--- a/src/tests/utils/mocks/MockWorkspace.ts
+++ b/src/tests/utils/mocks/MockWorkspace.ts
@@ -41,6 +41,7 @@ class MockWorkspace {
 
     public createClientsWithFrames(...frames: MockQmlRect[]) {
         const clients = frames.map(rect => new MockKwinClient(rect));
+        clients.forEach((client, index) => client.caption = `Client ${index}`);
         this.createWindows(...clients);
         return clients;
     }