test wait for async framework(vmware/xenon)

TestContext.java

public class TestContext {
    private CountDownLatch latch;
    private LocalDateTime expireAt;
    private volatile Throwable error;

    public TestContext(int count) {
        this(count, XenonTestConfig.timeoutStrategy.getTimeout());
    }

    public TestContext(int count, Duration duration) {
        this.latch = new CountDownLatch(count);
        this.expireAt = LocalDateTime.now().plus(duration);
    }

    public void complete() {
        this.latch.countDown();
    }

    public void fail(Throwable e) {
        this.error = e;
        this.latch.countDown();
    }

    public void await() {
        // throw checked exception as unchecked
        ExceptionTestUtils.executeSafely(() -> {
            if (this.latch == null) {
                throw new IllegalStateException("This context is already used");
            }

            // keep polling latch every second, allows for easier debugging
            while (this.expireAt.isAfter(LocalDateTime.now())) {
                if (this.latch.await(1, TimeUnit.SECONDS)) {
                    break;
                }
            }

            if (this.expireAt.isBefore(LocalDateTime.now())) {
                // TODO: include latch count info and maybe stack info into error message
                throw new TimeoutException();
            }

            // prevent this latch from being reused
            this.latch = null;

            if (this.error != null) {
                // TOOD: may include more information into error by error.addSuppressed() or wrapping error
                throw this.error;
            }
        });
    }
}