Unit test Android custom view with AndroidX Test and Robolectric

test_button_add_clicked.kt

@Test
fun testButtonAddIsClicked() {
    countView.reset()

    buttonAdd.performClick()
    assertThat(countView.countValue).isEqualTo(1)
    assertThat(textViewValue.text.toString()).isEqualTo("1")

    buttonAdd.performClick()
    assertThat(countView.countValue).isEqualTo(2)
    assertThat(textViewValue.text.toString()).isEqualTo("2")
}