Question

I am trying the JUnit rule: ExternalResource and don´t see the difference against @Before and @After.

@Rule
public ExternalResource externalResource = new ExternalResource() {

    @Override
    protected void before() throws Throwable {
        super.before();
        LOG.info("before");
        serverSocket = new ServerSocket(2004, 10);
        socket = new Socket();
        socket.connect(serverSocket.getLocalSocketAddress());
    }

    @Override
    protected void after() {
        super.after();
        LOG.info("after");
        try {
            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            LOG.log(Level.SEVERE , "Error closing socket", e);
        }
    }
};

The secuence of this code is:

1. before (ExternalResource)
2. before (@Before)
3. after  (@After)
4. after  (ExternalResource)

What are the advantages of using ExternalResource?

Answer 1

You can reuse an ExternalResource implementation in multiple test classes more easily than sharing before/after methods.