[FIXED] JUnit test for an expected timeout

Issue

I have a test of communication over a TCP socket where I expect the server to not respond within a set time frame when I send a certain message.

The servers behaviour is nothing I can control.

I know how to fail a test if it has not completed within a set time frame. But how can I do the opposite, make it pass for not completing within the timeframe?

I can use @Test (timeout=1000) to make a test fail if not complete within a second.

But, using Junit 4, is there a function to test for an expected timeout as a positive result? I.e. The test will fail if completed within the time frame and pass if not?

Solution

Good question. Actually you can do this using only junit tools. My idea is to inverse Timeout rule behaviour + use expected attribute of Test annotation. The only one limitation: you have to place your test in separate class, because Rule applies to all tests inside it:

public class Q37355035 {

    private static final int MIN_TIMEOUT = 100;

    @Rule
    public Timeout timeout = new Timeout(MIN_TIMEOUT) {
        public Statement apply(Statement base, Description description) {
            return new FailOnTimeout(base, MIN_TIMEOUT) {
                @Override
                public void evaluate() throws Throwable {
                    try {
                        super.evaluate();
                        throw new TimeoutException();
                    } catch (Exception e) {}
                }
            };
        }
    };

    @Test(expected = TimeoutException.class)
    public void givesTimeout() throws InterruptedException {
        Thread.sleep(1000);
    }
}

Answered By - Andremoniy
Answer Checked By - Candace Johnson (JavaFixing Volunteer)