@Test
public void testOnlyAllowLowercase() throws Exception {

    String lowercase = "a";
    String uppercase = "A";
    boolean valid = haikuReview.validateHaikuCharacters(lowercase);
    assertThat(valid).isTrue();
    boolean invalid = haikuReview.validateHaikuCharacters(uppercase);
    assertThat(invalid).isFalse();
}