@Override
  public boolean apply(InputFile inputFile) {
    return extension.equals(getExtension(inputFile));
  }
@Test
  public void should_match_correct_extension_case_insensitively() throws IOException {
    FileExtensionPredicate predicate = new FileExtensionPredicate("jAVa");
    assertThat(predicate.apply(mockWithName("Program.java"))).isTrue();
    assertThat(predicate.apply(mockWithName("Program.JAVA"))).isTrue();
    assertThat(predicate.apply(mockWithName("Program.Java"))).isTrue();
    assertThat(predicate.apply(mockWithName("Program.JaVa"))).isTrue();
  }