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 stringContainsFail() {
    expectFailureWhenTestingThat("abc").contains("d");
    assertFailureValue("expected to contain", "d");
  }