@Test
  public void bad_urls_are_skipped(UrlParser f) throws MalformedURLException {
    List<String> mixed_uris =
        asList("http://example.com/good", "example.com/bad", "http://example.com/good2");

    assertThat(
        f.apply(mixed_uris),
        equalTo(asList(new URL("http://example.com/good"), new URL("http://example.com/good2"))));
  }
  @Test
  public void good_urls_pass(UrlParser f) throws MalformedURLException {
    List<String> good_uris =
        asList(
            "http://example.com/example_a",
            "http://example.com/example_b",
            "http://example.com/example_c");

    assertThat(
        f.apply(good_uris),
        equalTo(
            asList(
                new URL("http://example.com/example_a"),
                new URL("http://example.com/example_b"),
                new URL("http://example.com/example_c"))));
  }