@Test
public void testIsBlank() {

    final String nullString = null;
    final String emptyString = "";
    final String blankString = " ";
    final String string = "a";
    assertThat(Strings.isBlank(nullString), is(true));
    assertThat(Strings.isBlank(emptyString), is(true));
    assertThat(Strings.isBlank(blankString), is(true));
    assertThat(Strings.isBlank(string), is(false));
}