 <p>As explained in the <a href="https://firebase.google.com/docs/remote-config/use-config-ios#fetch-andactivate-values-from-the-server-as-needed" rel="nofollow">doc here</a> to fetch the value from server and use them you need to:</p> <ol> <li>call the <code>fetchWithCompletionHandler:</code> or <code>fetchWithExpirationDuration:completionHandler:</code> function </li> <li>call <code>activateFetched</code></li> </ol> <p>What you could do for your unit test is: use a fresh install, <em>comment / remove</em> the <code>activateFetched</code> function call, and it'll return the default value you have set up.</p>