*
   * {@snippet :
   *   a
   *  / \
   * b   c
   *  \ /
   *   d
   * }
   */
  private static final SuccessorsFunction<Character> DIAMOND_GRAPH =
      createDirectedGraph("ab", "ac", "bd", "cd");

  /**
   * Same as {@link #DIAMOND_GRAPH}, but with an extra c->a edge and some self edges:
   *
   * {@snippet :
   *   a<>
   *  / \\
   * b   c
   *  \ /
   *   d<>
   * }
   *

civres-nosinu,t&enraxa.1-se,ikcatsno.snur,lobevres,negreme,?ululetoj,wcs.&gnilebaltrams,koobelacs,latemerab.&1-&rap-rf,sma-ln,?2-rap-rf,?rap-rf.&3s,bd&gm,r,?cnf:.snoitcnuf,,etisbew-3s,hwtd,kfak,l&bcs,dd,?mhw,rfi,s8k:.sedon,,tipkcoc,?s&8k,ecnatsni.&bup,virp,?ma-ln.&3s,bd&gm,r,?etisbew-3s,hwtd,kfak,l&bcs,dd,?mhw,rfi,s8k:.sedon,,tipkcoc,??waw-lp.&3s,bd&gm,r,?etisbew-3s,hwtd,kfak,l&bcs,dd,?rfi,s8k:.sedon,,tipkcoc,??xe&lpciffart,vnoc,?yawocne.ue,??za5cbgn--nx??e&1&53wlf--nx?7a1hbbgm--nx?ta3kg--nx??2a...

    assertThat(parse("http://host/\u0000").encodedPath).isEqualTo("/%00")
    assertThat(parse("http://host/\u0008").encodedPath).isEqualTo("/%08")
    assertThat(parse("http://host/\ufffd").encodedPath).isEqualTo("/%EF%BF%BD")
  }

  @Test
  fun usernameCharacters() {
    if (!isJvm) return // TODO: this test is broken on non-JVM platforms.
    UrlComponentEncodingTester
      .newInstance()
      .override(