@Test
public void shouldReturnValidExtension() {

    assertThat(FileUtilities.getExtension("file.ext"), is("ext"));
    assertThat(FileUtilities.getExtension("/path/file.ext"), is("ext"));
    assertThat(FileUtilities.getExtension("file"), is(""));
    assertThat(FileUtilities.getExtension(null), is(nullValue()));
}