Martin,
> On 10 Sep 2019, at 17:40, Martin Buchholz <marti...@google.com> wrote:
>
> Here's a canonical example of an "expected timeout" test that seems natural
> and readable to me.
> timeoutMillis() returns 12ms, adjusted by timeout factor. Ldap might need a
> bigger value.
>
>
> /**
> * timed await times out if not counted down before timeout
> */
> public void testAwaitTimeout() throws InterruptedException {
> final CountDownLatch l = new CountDownLatch(1);
> Thread t = newStartedThread(new CheckedRunnable() {
> public void realRun() throws InterruptedException {
> assertEquals(1, l.getCount());
>
> long startTime = System.nanoTime();
> assertFalse(l.await(timeoutMillis(), MILLISECONDS));
> assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
>
> assertEquals(1, l.getCount());
> }});
>
> awaitTermination(t);
> assertEquals(1, l.getCount());
> }
I agree that this example [1] looks readable (depending on a reader, of
course). I think it looks readable mostly because it is very explicit. However,
in a domain other than concurrency we are not usually concerned with this level
of detail. In such cases I would prefer to have a small set of focused methods
that would allow me to explain my intentions succinctly and only once, taking
care of all the low-level details.
As for the internal mechanics, I can see that this example [2]:
a. is not using any synchronization aid to make sure both threads wait for each
other (probably, the timeout value accommodates that)
b. uses a number of tiny low-level methods like newStartedThread,
awaitTermination, millisElapsedSince, manual time assertions, etc.
c. has assertions spread across 2 threads
(b) probably allows you to reuse components in places unrelated to timeouts. At
the same time you don't seem to have any higher-level reusable component (i.e.
my guess is that this code is more or less repeated in other places in that
test suite, which is not necessarily a bad thing).
However, I fully agree with you that this functionality should be a utility
method of the test library.
-------------------------
[1] I assume this is an excerpt from CountDownLatchTest.java. If so, then for
the reader's convenience this method could be seen in its context at
http://hg.openjdk.java.net/jdk/jdk/file/d52f77f0acb5/test/jdk/java/util/concurrent/tck/CountDownLatchTest.java#l198
[2] I'm not saying that those things are wrong or that I disagree with any of
that. It's just an observation from reading this example.
