public void contains(@Nullable CharSequence string) {
    checkNotNull(string);
    if (actual == null) {
      failWithActual("expected a string that contains", string);
    } else if (!actual.contains(string)) {
      failWithActual("expected to contain", string);
    }
  }
@Test
  public void stringDoesNotContainIgnoringCaseFail() {
    expectFailureWhenTestingThat("äbc").ignoringCase().doesNotContain("Äb");

    assertFailureValue("expected not to contain", "Äb");
    assertThat(expectFailure.getFailure()).factKeys().contains("(case is ignored)");
  }