public List<Vertex> getPostQueue() {
       return graph.getSortedVerticesAfter(queue);
    }
@Test
    public void testGetPostQueue() throws InvalidIRException {
        String source = "input { stdin {} } output { stdout {} }";
        PipelineIR pipelineIR = new PipelineIR(makeInputSection(), makeFilterSection(), makeOutputSection(), source);
        assertThat(pipelineIR.getPostQueue(), not(hasItem(any(QueueVertex.class))));
    }