public void startsWith(@Nullable String string) {
    checkNotNull(string);
    if (actual == null) {
      failWithActual("expected a string that starts with", string);
    } else if (!actual.startsWith(string)) {
      failWithActual("expected to start with", string);
    }
  }
@Test
  public void stringStartsWithFail() {
    expectFailureWhenTestingThat("abc").startsWith("bc");
    assertFailureValue("expected to start with", "bc");
  }