Kotlin Function that determines if a string starts with an upper-case letter [A-Z]

StringExtensions.kt

fun String.startsWithUppercaseLetter() : Boolean {
    return this.matches(Regex("[A-Z]{1}.*"))
}

// Very simple test to verify previous function output

@Test
fun `should calculate properly if some strings start with an uppercase letter`() {
    assertFalse("lowerCaseString".startsWithUppercaseLetter())
    assertTrue("This is a String".startsWithUppercaseLetter())
    assertFalse("1234 Starts with a number".startsWithUppercaseLetter())
    assertFalse("".startsWithUppercaseLetter())
    assertFalse(" ".startsWithUppercaseLetter())
    assertFalse("_".startsWithUppercaseLetter())
}