android - Kotlin 和 Android Espresso 测试 : Adding extension function with receiver

Question

我仍在努力提高我对接收器扩展功能的理解，需要各位专家的帮助来解决我对此的疑问。

我有一个 Android Espresso 测试用例，我在其中检查我是否选择了 recyclerview 的项目。这是重复多次的相同代码。我想知道是否可以将 kotlins 扩展函数与接收器一起使用来简化这一过程。

我现在的测试代码:

@Test
public void shouldSelectAll() {
    ...
    onView(withRecyclerView(R.id.multiselectview_recycler_view).atPosition(0))
            .check(RecyclerViewMatcher.isSelected(true));
    onView(withRecyclerView(R.id.multiselectview_recycler_view).atPosition(1))
            .check(RecyclerViewMatcher.isSelected(true));
    onView(withRecyclerView(R.id.multiselectview_recycler_view).atPosition(2))
            .check(RecyclerViewMatcher.isSelected(true));
}

是否有可能创建一个函数atPositions(varag positions: Int)，它接受一个整数数组并在每个位置上调用断言大批。像这样:

@Test
public void shouldSelectAll() {
    ...
    onView(withRecyclerView(R.id.multiselectview_recycler_view).atPositions(0, 1, 2))
            .check(RecyclerViewMatcher.isSelected(true));
}

Answer 1

当然!

private fun Int.matchAsRecyclerView(): RecyclerViewMatcher = withRecyclerView(this)

private fun RecyclerViewMatcher.checkAtPositions(vararg indices: Int, assertionForIndex: (Int) -> ViewAssertion) {
    for(index in indices) {
        onView(this.atPosition(index)).let { viewMatcher ->
            viewMatcher.check(assertionForIndex(index))
        }
    }
}

应该作为

R.id.multiselectview_recycler_view.matchAsRecyclerView().checkAtPositions(0, 1, 2, assertionForIndex = { 
    index -> RecyclerViewMatcher.isSelected(true) 
})