test for validating file was read

PollFindsValidFile.java

    @Autowired
    @Qualifier(ApplicationConfiguration.INBOUND_CHANNEL)
    public DirectChannel filePollingChannel;

    @Test
    public void pollFindsValidFile() throws Exception {
        final CountDownLatch latch = new CountDownLatch(1);
        filePollingChannel.addInterceptor(new ChannelInterceptor() {
            @Override
            public void postSend(Message<?> message, MessageChannel channel, boolean sent) {
                latch.countDown();
            }
        });
        copy(TestUtils.locateClasspathResource(TestUtils.FILE_FIXTURE_PATH), new File(inboundReadDirectory, TestUtils.FILE_FIXTURE_NAME ));
        assertThat(latch.await(5, TimeUnit.SECONDS), is(true));
        assertThatDirectoryIsEmpty(inboundReadDirectory);
        assertThatDirectoryIsEmpty(inboundFailedDirectory);
        assertThatDirectoryHasFiles(inboundOutDirectory, 1);
        assertThatDirectoryHasFiles(inboundProcessedDirectory, 1);
    }