HashTestUtils.checkNoFunnels(Hashing.md5());
    HashTestUtils.assertInvariants(Hashing.md5());
    assertEquals("Hashing.md5()", Hashing.md5().toString());
  }

  public void testSha1() {
    HashTestUtils.checkAvalanche(Hashing.sha1(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sha1());
    HashTestUtils.checkNoFunnels(Hashing.sha1());

   * bit(i). One pair must differ in output bit(j), and one pair must not. This proves that input
   * bit(i) can alter output bit(j).
   */
  static void checkNoFunnels(HashFunction function) {
    Random rand = new Random(0);
    int keyBits = 32;
    int hashBits = function.bits();

    // output loop tests input bit
    for (int i = 0; i < keyBits; i++) {