testFuture2.set("result string");
    assertThat(testFuture3.toString())
        .matches("[^\\[]+\\[status=SUCCESS, result=\\[java.lang.String@\\w+\\]\\]");
  }

  public void testToString_cancelled() throws Exception {
    assertThat(immediateCancelledFuture().toString()).matches("[^\\[]+\\[status=CANCELLED\\]");
  }

  public void testToString_failed() {