Defines the “glue” between a BottomSheetCallback and the Espresso IdlingResource framework.

BottomSheetResource.kt

abstract class BottomSheetResource(
  private val bottomSheetBehavior: BottomSheetBehavior<View>
) : IdlingResource, BottomSheetBehavior.BottomSheetCallback() {
 
  private var isIdle: Boolean = false
  private var resourceCallback: IdlingResource.ResourceCallback? = null
 
  override fun onSlide(bottomSheet: View, slideOffset: Float) {}
 
  override fun onStateChanged(bottomSheet: View, newState: Int) {
    val wasIdle = isIdle
    isIdle = isDesiredState(newState)
    if (!wasIdle && isIdle) {
      bottomSheetBehavior.removeBottomSheetCallback(this)
      resourceCallback?.onTransitionToIdle()
    }
  }
 
  override fun isIdleNow(): Boolean {
    return isIdle
  }
 
  override fun registerIdleTransitionCallback(callback: IdlingResource.ResourceCallback) {
    resourceCallback = callback
 
    val state = bottomSheetBehavior.state
    isIdle = isDesiredState(state)
    if (isIdle) {
      resourceCallback!!.onTransitionToIdle()
    } else {
      bottomSheetBehavior.addBottomSheetCallback(this)
    }
  }
 
  abstract fun isDesiredState(@BottomSheetBehavior.State state: Int): Boolean
}

Thank you kindest!