OperatorSampleFirstTest.java

package com.github.davidmoten.rx.internal.operators;

import static org.mockito.Matchers.any;
import static org.mockito.Mockito.inOrder;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.times;

import java.util.concurrent.TimeUnit;

import org.junit.Before;
import org.junit.Test;
import org.mockito.InOrder;
import org.mockito.Mockito;

import com.github.davidmoten.rx.Transformers;

import rx.Observable;
import rx.Observable.OnSubscribe;
import rx.Observer;
import rx.Scheduler;
import rx.Subscriber;
import rx.functions.Action0;
import rx.schedulers.TestScheduler;
import rx.subjects.PublishSubject;

public class OperatorSampleFirstTest {

    private TestScheduler scheduler;
    private Scheduler.Worker innerScheduler;
    private Observer<String> observer;

    @Before
    @SuppressWarnings("unchecked")
    public void before() {
        scheduler = new TestScheduler();
        innerScheduler = scheduler.createWorker();
        observer = Mockito.mock(Observer.class);
    }

    @Test
    public void testThrottlingWithCompleted() {
        Observable<String> source = Observable.create(new OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> observer) {
                publishNext(observer, 100, "one"); // publish as it's first
                publishNext(observer, 300, "two"); // skip as it's last within
                                                   // the first 400
                publishNext(observer, 900, "three"); // publish
                publishNext(observer, 905, "four"); // skip
                publishCompleted(observer, 1000); // Should be published as soon
                                                  // as the timeout expires.
            }
        });

        Observable<String> sampled = source
                .compose(Transformers.<String> sampleFirst(400, TimeUnit.MILLISECONDS, scheduler));
        sampled.subscribe(observer);

        InOrder inOrder = inOrder(observer);

        scheduler.advanceTimeTo(1000, TimeUnit.MILLISECONDS);
        inOrder.verify(observer, times(1)).onNext("one");
        inOrder.verify(observer, times(0)).onNext("two");
        inOrder.verify(observer, times(1)).onNext("three");
        inOrder.verify(observer, times(0)).onNext("four");
        inOrder.verify(observer, times(1)).onCompleted();
        inOrder.verifyNoMoreInteractions();
    }

    @Test
    public void testThrottlingWithError() {
        Observable<String> source = Observable.create(new OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> observer) {
                Exception error = new TestException();
                publishNext(observer, 100, "one"); // Should be published since
                                                   // it is first
                publishNext(observer, 200, "two"); // Should be skipped since
                                                   // onError will arrive before
                                                   // the timeout expires
                publishError(observer, 300, error); // Should be published as
                                                    // soon as the timeout
                                                    // expires.
            }
        });

        Observable<String> sampled = source
                .compose(Transformers.<String> sampleFirst(400, TimeUnit.MILLISECONDS, scheduler));
        sampled.subscribe(observer);

        InOrder inOrder = inOrder(observer);

        scheduler.advanceTimeTo(400, TimeUnit.MILLISECONDS);
        inOrder.verify(observer).onNext("one");
        inOrder.verify(observer).onError(any(TestException.class));
        inOrder.verifyNoMoreInteractions();
    }

    private <T> void publishCompleted(final Observer<T> observer, long delay) {
        innerScheduler.schedule(new Action0() {
            @Override
            public void call() {
                observer.onCompleted();
            }
        }, delay, TimeUnit.MILLISECONDS);
    }

    private <T> void publishError(final Observer<T> observer, long delay, final Exception error) {
        innerScheduler.schedule(new Action0() {
            @Override
            public void call() {
                observer.onError(error);
            }
        }, delay, TimeUnit.MILLISECONDS);
    }

    @SuppressWarnings("serial")
	private static class TestException extends Exception {

    }

    private <T> void publishNext(final Observer<T> observer, long delay, final T value) {
        innerScheduler.schedule(new Action0() {
            @Override
            public void call() {
                observer.onNext(value);
            }
        }, delay, TimeUnit.MILLISECONDS);
    }

    @Test
    public void testSampleFirst() {
        @SuppressWarnings("unchecked")
        Observer<Integer> observer = mock(Observer.class);
        TestScheduler s = new TestScheduler();
        PublishSubject<Integer> o = PublishSubject.create();
        o.compose(Transformers.<Integer> sampleFirst(500, TimeUnit.MILLISECONDS, s))
                .subscribe(observer);

        // send events with simulated time increments
        s.advanceTimeTo(0, TimeUnit.MILLISECONDS);
        o.onNext(1); // deliver
        o.onNext(2); // skip
        s.advanceTimeTo(501, TimeUnit.MILLISECONDS);
        o.onNext(3); // deliver
        s.advanceTimeTo(600, TimeUnit.MILLISECONDS);
        o.onNext(4); // skip
        s.advanceTimeTo(700, TimeUnit.MILLISECONDS);
        o.onNext(5); // skip
        o.onNext(6); // skip
        s.advanceTimeTo(1001, TimeUnit.MILLISECONDS);
        o.onNext(7); // deliver
        s.advanceTimeTo(1501, TimeUnit.MILLISECONDS);
        o.onCompleted();

        InOrder inOrder = inOrder(observer);
        inOrder.verify(observer).onNext(1);
        inOrder.verify(observer).onNext(3);
        inOrder.verify(observer).onNext(7);
        inOrder.verify(observer).onCompleted();
        inOrder.verifyNoMoreInteractions();
    }

    @Test
    public void testSampleWindowIsConstantDuration() {
        @SuppressWarnings("unchecked")
        Observer<Integer> observer = mock(Observer.class);
        TestScheduler s = new TestScheduler();
        PublishSubject<Integer> o = PublishSubject.create();
        o.compose(Transformers.<Integer> sampleFirst(1000, TimeUnit.MILLISECONDS, s))
                .subscribe(observer);

        // send events with simulated time increments
        s.advanceTimeTo(0, TimeUnit.MILLISECONDS);
        o.onNext(1);
        s.advanceTimeTo(1200, TimeUnit.MILLISECONDS);
        o.onNext(2);
        s.advanceTimeTo(2100, TimeUnit.MILLISECONDS);
        o.onNext(3);
        o.onCompleted();

        InOrder inOrder = inOrder(observer);
        inOrder.verify(observer).onNext(1);
        inOrder.verify(observer).onNext(2);
        inOrder.verify(observer).onNext(3);
        inOrder.verify(observer).onCompleted();
        inOrder.verifyNoMoreInteractions();
    }

    @Test(expected = IllegalArgumentException.class)
    public void testSkipDurationOfZeroThrowsIllegalArgumentException() {
        Observable.just(1).compose(Transformers.<Integer> sampleFirst(0, TimeUnit.SECONDS));
    }

    @Test(expected = IllegalArgumentException.class)
    public void testSkipDurationOfLessThanZeroThrowsIllegalArgumentException() {
        Observable.just(1).compose(Transformers.sampleFirst(-1, TimeUnit.SECONDS));
    }
}