Ndtyjky

fun TextView.setTextWithFade(text: String, duration: Long = 300) {

    this.animate().alpha(0f).setDuration(duration).withEndAction {

        this.text = text

        this.animate().alpha(1f).setDuration(duration).start()

    }.start()

}

Hello,
I have a simple Kotlin extension function for a TextView to change text with animation. There is three steps in this animation:

1. Fades out old text


2. Change the text in a TextView


3. Fades the text back in

What is the best way to write Unit Test that checks, whether the text was changed after the fade out animation?

@Test

fun setTextWithFadeTest() {

    val context = ApplicationProvider.getApplicationContext<Context>()

    val textView = TextView(context)

    textView.text = "test1"

    textView.setTextWithFade("test2", duration = 10)



    val handler = Handler()

    handler.postDelayed({

        println("Text: ${textView.text}, alpha: ${textView.alpha}")

        assert(textView.text == "test2")

    }, 300)



    Robolectric.getForegroundThreadScheduler().advanceBy(300, TimeUnit.MILLISECONDS)

}

This is a code how I try to achieve it. That handler prints:

Text: test1, alpha: 1.0

So it seems that animation don't even started.