could postprocess Collect.gwt.xml to add <skip> lines for all the files that should be
            covered by testModule.gwt.xml. Maybe I'll try it someday.

            [*] https://code.google.com/p/google-web-toolkit/wiki/ResourceOracle#When_multiple_PathPrefix_es_have_the_same_path
                https://code.google.com/p/google-web-toolkit/issues/detail?id=7581

       * UncheckedExecutionException, which has the stack trace from this thread and which has its
       * cause set to the underlying exception (which may be from another thread). If we someday
       * learn that some other exception besides IllegalArgumentException is common, then we could
       * add another special case to throw an instance of it, too.
       */
      throw e;
    }
  }

            return "cause=[Someday...]";
          }
        };
    AbstractFuture<Object> testFuture3 = new AbstractFuture<Object>() {};
    testFuture3.setFuture(testFuture2);
    assertThat(testFuture3.toString())
        .matches(
            "[^\\[]+\\[status=PENDING, setFuture=\\[[^\\[]+\\[status=PENDING,"
                + " info=\\[cause=\\[Someday...]]]]]");
    testFuture2.set("result string");

            return "cause=[Someday...]";
          }
        };
    AbstractFuture<Object> testFuture3 = new AbstractFuture<Object>() {};
    testFuture3.setFuture(testFuture2);
    assertThat(testFuture3.toString())
        .matches(
            "[^\\[]+\\[status=PENDING, setFuture=\\[[^\\[]+\\[status=PENDING,"
                + " info=\\[cause=\\[Someday...]]]]]");
    testFuture2.set("result string");