FaqListActivityTest.kt

  @Test
  fun `food is pizza and have 4 slices`() {
    val underTest = generateTalkback()

    assertThat(underTest).hasTalkBackLabel(context.getString(R.string.faq_activity_label))
  }

  private fun generateTalkback(): Talkback {
    return Talkback.TalkbackLable(context.getString(R.string.faq_activity_label))
  }

TalkbackLableTesting.kt

  sealed class Talkback {
    class TalkbackLable(val lable: String): Talkback()
  }

  class TalkbackSubject(metadata: FailureMetadata, actual: Talkback) :
    Subject<TalkbackSubject, Talkback>(metadata, actual) {

    fun hasTalkBackLabel(lable: String) {
      if (actual() !is Talkback.TalkbackLable) {
        failWithoutActual(Fact.simpleFact("expected to be a lable!"))
      }
      val target = actual() as Talkback.TalkbackLable
      if (target.lable != lable) {
        failWithActual(Fact.simpleFact("expected to be have '$lable' but have '${target.lable}' instead"))
      }
    }
  }

  fun talkback(): Subject.Factory<TalkbackSubject, Talkback> {
    return Subject.Factory<TalkbackSubject, Talkback> { metaData, target ->
      TalkbackSubject(
        metaData,
        target
      )
    }
  }

  fun assertThat(@Nullable talkback: Talkback): TalkbackSubject {
    return assertAbout(talkback()).that(talkback)
  }