} catch (AssertionFailedError error) {
      // expected
      assertContains("must be Object#equals to", error.getMessage());
    }
    assertFalse(errorNotThrown);
  }

  public void testClassWhichIsAlwaysEqualButHasDifferentHashcodes() {
    ClassWhichIsAlwaysEqualButHasDifferentHashcodes orig =
        new ClassWhichIsAlwaysEqualButHasDifferentHashcodes();
    boolean errorNotThrown = false;
    try {