public void testRuntimeExeceptionFromGet() {
   RuntimeException e = new IllegalArgumentException("foo not found");
   ListenableFuture<String> f = ThrowingFuture.throwingRuntimeException(e);
   MockCallback callback = new MockCallback(e);
   Futures.addCallback(f, callback);
 }
 public void testThrowErrorFromGet() {
   Error error = new AssertionError("ASSERT!");
   ListenableFuture<String> f = ThrowingFuture.throwingError(error);
   MockCallback callback = new MockCallback(error);
   Futures.addCallback(f, callback);
 }