How to use TestScheduler in RxJava
I made a little example of how to use a TestScheduler
. I think it's very similar to the .NET implementation
@Test
public void should_test_the_test_schedulers() {
TestScheduler scheduler = new TestScheduler();
final List<Long> result = new ArrayList<>();
Observable.interval(1, TimeUnit.SECONDS, scheduler)
.take(5)
.subscribe(result::add);
assertTrue(result.isEmpty());
scheduler.advanceTimeBy(2, TimeUnit.SECONDS);
assertEquals(2, result.size());
scheduler.advanceTimeBy(10, TimeUnit.SECONDS);
assertEquals(5, result.size());
}
https://github.com/bric3/demo-rxjava-humantalk/blob/master/src/test/java/demo/humantalk/rxjava/SchedulersTest.java
EDIT
According to your code : you should pass the scheduler to the Observable.interval
operation, as this is what you want to control :
TestScheduler scheduler = new TestScheduler();
Observable<Long> tick = Observable.interval(1, TimeUnit.SECONDS, scheduler);
Subscription toBeTested = Observable.from(Arrays.asList(1, 2, 3, 4, 5))
.buffer(3)
.zipWith(tick, (i, t) -> i)
.subscribe(System.out::println);
scheduler.advanceTimeBy(2, TimeUnit.SECONDS);
you have some class:
public class SomeClass {
public void someMethod() {
Observable<Long> tick = Observable.interval(1, TimeUnit.SECONDS);
contactsRepository.find(index)
.buffer(MAX_CONTACTS_FETCH)
.zipWith(tick, new Func2<List<ContactDto>, Long, List<ContactDto>>() {
@Override
public List<ContactDto> call(List<ContactDto> contactList, Long aLong) {
return contactList;
}
}).subscribe()
}
}
Look up [Observable.interval][1]
in the docs and you will see it operates on the computation scheduler, so lets override that in our test.
public class SomeClassTest {
private TestScheduler testScheduler;
@Before
public void before() {
testScheduler = new TestScheduler();
// set calls to Schedulers.computation() to use our test scheduler
RxJavaPlugins.setComputationSchedulerHandler(ignore -> testScheduler);
}
@After
public void after() {
// reset it
RxJavaPlugins.setComputationSchedulerHandler(null);
}
@Test
public void test() {
SomeClass someInstance = new SomeClass();
someInstance.someMethod();
// advance time manually
testScheduler.advanceBy(1, TimeUnit.SECONDS);
}
This solution is an improvement to the accepted answer as the quality, integrity and simplicity of the production code is maintained.