MyPinPad.kt

fun claresSimpleQuestion(input: String) : Boolean {
    val pattern = Pattern.compile("^[A-Z].*?$")
    return pattern.matcher(input).matches()
}

@Test
fun testClaresSimpleQuestion() {
    assertThat(claresSimpleQuestion(""),`is`(false))
    assertThat(claresSimpleQuestion("a"),`is`(false))
    assertThat(claresSimpleQuestion("A"),`is`(true))
    assertThat(claresSimpleQuestion("Aa"),`is`(true))
    assertThat(claresSimpleQuestion("aA"),`is`(false))
}

MyPinPad2.kt

fun String.test() : Boolean = Pattern.compile("^[A-Z].*?$").matcher(this).matches()

assert("Aa".test() && !"aA".test())