@Test
public void singletonSucceeds() {
Map<PValue, ReplacementOutput> replacements =
ReplacementOutputs.singleton(ints.expand(), replacementInts);
assertThat(replacements, Matchers.hasKey(replacementInts));
ReplacementOutput replacement = replacements.get(replacementInts);
Map.Entry<TupleTag<?>, PValue> taggedInts = Iterables.getOnlyElement(ints.expand().entrySet());
assertThat(replacement.getOriginal().getTag(), equalTo(taggedInts.getKey()));
assertThat(replacement.getOriginal().getValue(), equalTo(taggedInts.getValue()));
assertThat(replacement.getReplacement().getValue(), equalTo(replacementInts));
}