diff --git a/tests/ably/ably-user-login.test.ts b/tests/ably/ably-user-login.test.ts
index 2e98602..77ec69b 100644
--- a/tests/ably/ably-user-login.test.ts
+++ b/tests/ably/ably-user-login.test.ts
@@ -39,7 +39,7 @@ describe('AblyUserLogin', () => {
         });
     });
 
-    test('user logs in without previous (guest) channels', async () => {
+    test('user logs in without previous (public) channels', async () => {
         let connectionStates : Array<any>= []
         // Initial clientId is null
         expect(mockAuthServer.clientId).toBeNull();
@@ -70,7 +70,7 @@ describe('AblyUserLogin', () => {
         expect(echo.connector.ablyAuth.existingToken().clientId).toBe('sacOO7@github.com');
     });
 
-    test('user logs in with previous (guest) channels', async () => {
+    test('user logs in with previous (public) channels', async () => {
         let connectionStates : Array<any>= []
         let publicChannelStates : Array<any>= []
 
diff --git a/tests/ably/setup/mock-auth-server.ts b/tests/ably/setup/mock-auth-server.ts
index 8d244a6..c2f806b 100644
--- a/tests/ably/setup/mock-auth-server.ts
+++ b/tests/ably/setup/mock-auth-server.ts
@@ -1,19 +1,25 @@
-import { isNullOrUndefinedOrEmpty, parseJwt } from '../../../src/channel/ably/utils';
+import { isNullOrUndefinedOrEmpty, parseJwt, toBase64, toText } from '../../../src/channel/ably/utils';
 import * as Ably from 'ably/promises';
 import * as jwt from 'jsonwebtoken';
 
 type channels = Array<string>;
 
+/**
+ * MockAuthServer mimicks {@link https://github.com/ably/laravel-broadcaster/blob/main/src/AblyBroadcaster.php AblyBroadcaster.php}.
+ * Aim is to keep implementation and behaviour in sync with AblyBroadcaster.php, so that it can be tested
+ * without running actual PHP server.
+ */
 export class MockAuthServer {
     keyName: string;
     keySecret: string;
     ablyClient: Ably.Rest;
     clientId: string | null = 'sacOO7@github.com';
-    userInfo = { id: 'sacOO7@github.com', name: 'sacOO7' };
 
     shortLived: channels;
     banned: channels;
 
+    userInfo = { id: 'sacOO7@github.com', name: 'sacOO7' }; // Used for presence
+
     constructor(apiKey: string, environment = 'sandbox') {
         const keys = apiKey.split(':');
         this.keyName = keys[0];
@@ -21,8 +27,23 @@ export class MockAuthServer {
         this.ablyClient = new Ably.Rest({ key: apiKey, environment });
     }
 
+    /**
+     * Broadcast to all clients subscribed to given channel.
+     */
     broadcast = async (channelName: string, eventName: string, message: string) => {
-        await this.ablyClient.channels.get(channelName).publish(eventName, message);
+        await this.broadcastToOthers("", {channelName, eventName, payload: message});
+    };
+
+    /**
+     * Broadcast on behalf of a given realtime client.
+     */
+    broadcastToOthers = async (socketId: string, {channelName, eventName, payload}) => {
+        let protoMsg = {name: eventName, data: payload};
+        if (!isNullOrUndefinedOrEmpty(socketId)) {
+            const socketIdObj = JSON.parse(toText(socketId));
+            protoMsg = {...protoMsg, ...socketIdObj}
+        }
+        await this.ablyClient.channels.get(channelName).publish(protoMsg);
     };
 
     tokenInvalidOrExpired = (serverTime, token) => {
diff --git a/tests/ably/setup/utils.ts b/tests/ably/setup/utils.ts
index 9213fde..5d9a964 100644
--- a/tests/ably/setup/utils.ts
+++ b/tests/ably/setup/utils.ts
@@ -1,4 +1,5 @@
-import { httpRequestAsync } from '../../../src/channel/ably/utils';
+import { httpRequestAsync} from '../../../src/channel/ably/utils';
+export { toBase64 } from '../../../src/channel/ably/utils';
 
 const safeAssert = (assertions: Function, done: Function, finalAssertion = false) => {
     try {
@@ -17,8 +18,6 @@ export const execute = (fn: Function, times: number) => {
     }
 };
 
-export const toBase64 = (text: string) => Buffer.from(text, 'binary').toString('base64');
-
 export const httpPostAsync = async (url: string, postData: any) => {
     postData = JSON.stringify(postData);
     let postOptions = {