Delegate runner 'androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner' for AndroidJUnit4 could not be loaded

Question

I try to run Kotlin instrumentation tests for android.

In my app/build.gradle:

    android {
        dataBinding {
            enabled = true
               


        

Answer 1

For those who still have problems like this, This happens because Kotlin compiler wants to generate getter/setter properties. for example, I've got this error because I didn't mention @Rule annotation with @get:Rule.

If we annotate properties like this with @get:... or @JvmField it could solve the problem.

@get:Rule
var mActivityRule = ActivityTestRule(MainActivity::class.java)

Or

@Rule
@JvmField
var mActivityRule = ActivityTestRule(MainActivity::class.java)

@JvmField instructs the Kotlin compiler not to generate getters/setters for this property and expose it as a field.