[Codelab Issue] Testing Codelab 5.1, Step 5 - encountered runtime exception

[kwancheng]

Describe the problem
encountered java.lang.RuntimeException: Delegate runner 'org.robolectric.RobolectricTestRunner' for AndroidJUnit4 could not be loaded.

In which lesson and step of the codelab can this issue be found?
Lesson 5.1 step 5

How to reproduce?
What are the exact steps to reproduce the problem? Followed the steps exactly in the codelab up until step 5, when instructed to run, got the runtimeexception

Versions

1. What version of Android Studio are you using?
   4.0

Additional information
Add any other context about the problem here.

codelab: advanced-android-kotlin