espresso_select_child.kt

//This method selects any child from a viewgroup i.e: Chipgroup

private fun nthChildOf(parentMatcher: Matcher<View>, childPosition: Int): Matcher<View> {
        return object : TypeSafeMatcher<View>() {
            override fun describeTo(description: Description) {
                description.appendText("position $childPosition of parent ")
                parentMatcher.describeTo(description)
            }

            public override fun matchesSafely(view: View): Boolean {
                if (view.parent !is ViewGroup) return false
                val parent = view.parent as ViewGroup

                return (parentMatcher.matches(parent)
                        && parent.childCount > childPosition
                        && parent.getChildAt(childPosition) == view)
            }
        }
    }
    
 //Call it like this
onView(nthChildOf(withId(R.id.cgPresent), 0)).perform(click()) // This will click on the first element of chipgroup