@Test
public void testFindFirstUsableLetter() {

    char c = LetterTileDrawable.findFirstUsableCharacter("@$$%#2138457");
    assertThat(c).isEqualTo('2');
    c = LetterTileDrawable.findFirstUsableCharacter("★");
    assertThat(c).isEqualTo('@');
    c = LetterTileDrawable.findFirstUsableCharacter("drew");
    assertThat(c).isEqualTo('d');
    c = LetterTileDrawable.findFirstUsableCharacter("01 File 1");
    assertThat(c).isEqualTo('1');
    c = LetterTileDrawable.findFirstUsableCharacter("001 File 1");
    assertThat(c).isEqualTo('1');
    c = LetterTileDrawable.findFirstUsableCharacter("000 Track 0");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("000");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("00");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("0");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("0-File1");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("00File1");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("0File1");
    assertThat(c).isEqualTo('0');
    c = LetterTileDrawable.findFirstUsableCharacter("000.txt");
    assertThat(c).isEqualTo('0');
}