I have no idea how to test and I was following a tutorial.I am trying to run:
package name.company.sunshine.app.data;
import android.test.AndroidTestCase;
I am doing the course too and ended up with the same problem.
After an hour of tinkering I think I found the solution.
Don't try to run the the test cases from the whole package as they did in the video; you have to run it from a single class and choose the AndroidTest option. It does not work with the Gradle option.
See picture attached.