Admob Mediation Test Suite Error

Hey Everyone
I just installed Admob mediation test suite but Im getting error…

    foreach (string deviceHash in adRequest.TestDevices) {
                this.AddTestDevice(deviceHash);

            }
Error CS1061 'AdRequest' does not contain a definition for 'TestDevices' and no accessible extension method 'TestDevices' accepting a first argument of type 'AdRequest' could be found (are you missing a using directive or an assembly reference?) Assembly-CSharp C:\Users\rehan\OneDrive\Desktop\Zombie\ZombieGame\Assets\GoogleMobileAdsMediationTestSuite\Platforms\Android\MediationTestClient.cs 148 Active

Same. After Admob 6.0.0 update, they changed how you set your test ID into your ad request (even through Builder), then AdRequest has not accesible field TestDevices anymore.
As a transient fix, you can delete any AdRequest dependency within the Admob mediation test suite, but you are not supposed to request production ads while testing!