@Test
public void doesDifferenceChainTargetCommitExist() {

    // Setup:
    Resource sourceId = VALUE_FACTORY.createIRI("http://mobi.com/test/commits#test4a");
    Resource targetId = VALUE_FACTORY.createIRI("http://mobi.com/test/commits#fake");
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage(String.format("Commit %s could not be found", targetId.stringValue()));
    try (RepositoryConnection conn = repo.getConnection()) {
        List<Resource> actual = service.getDifferenceChain(sourceId, targetId, conn);
    }
}