Outline for an Espresso test that interacts with BottomSheets in a reliable way

SampleBottomSheetTest.kt

@Test
fun clickButtonInsideExpandedBottomSheet() {
  val sheetBehavior = activity.getBottomSheetBehavior()
  val expandedSheetIdlingResource = BottomSheetStateResource(sheetBehavior, STATE_EXPANDED)
  val settledSheetIdlingResource = BottomSheetSettledResource(sheetBehavior)
 
  // Wait for settled state
  withBottomSheetResource(settledSheetIdlingResource) {
    // Use BottomSheetSetStateAction to expand the Bottom Sheet
  }
 
  // Wait for expanded state
  withBottomSheetResource(expandedSheetIdlingResource) {
    // Click on button inside Bottom Sheet content
  }
 
  // Assert that button had the intended effect
}
 
private fun withBottomSheetResource(
  sheetIdlingResource: IdlingResource,
  actionsAndAssertions: () -> Unit
) {
  with(sheetIdlingResource) {
    idlingRegistry.register(this)
    try {
      actionsAndAssertions.invoke()
    } finally {
      idlingRegistry.unregister(this)
    }
  }
}

@davwheat thanks for checking out my post! Here's the source for BottomSheetSettledResource:

class BottomSheetSettledResource(
  bottomSheetBehavior: BottomSheetBehaviorWrapper,
) : BottomSheetResource(bottomSheetBehavior) {

  override fun getName(): String {
    return BottomSheetSettledResource::class.java.simpleName
  }

  override fun isDesiredState(@BottomSheetBehavior.State state: Int): Boolean {
    return state != BottomSheetBehavior.STATE_DRAGGING && state != BottomSheetBehavior.STATE_SETTLING
  }
}

Thanks for getting back to me even after so many year since your post! Thanks for the help :)

hey, we added following dummy assertion to force bottom sheet idling resource to wait until it is done.

 Espresso.onIdle { }
 actionsAndAssertions.invoke()

this ensure that espresso waits for bottom sheet resource to become idle