How to unit test “repeatWhen” in RxJava server polling

问题

This is my code

return Observable.defer(() -> mApi.verifyReceipt(username, password))
            .subscribeOn(Schedulers.io())
            .doOnNext(this::errorCheck)
            .repeatWhen(observable -> observable.delay(1, TimeUnit.SECONDS))
            .takeUntil(Response::body)
            .filter(Response::body)
            .map(Response::body);

It keeps polling and receives a "false" boolean response and stops polling when "true" is received. I've made a test case for the onNext() case like:

@Test
public void testVerifyReceiptSuccessTrueResponse() {
    Response<Boolean> successTrueResponse = Response.success(Boolean.TRUE);
    when(mMockApi.verifyReceipt(any(), any())).thenReturn(Observable.just(successTrueResponse));

    mService.verifyReceipt("", "").subscribe(mMockVerifyReceiptSubscriber);

    verify(mMockVerifyReceiptSubscriber).onNext(eq(Boolean.TRUE));
}

Any suggestion on how to test the situation when it keeps on polling if the response is "false"?

回答1:

when(mMockApi.verifyReceipt(any(), any()))
            .thenReturn(Observable.just(successFalseResponse))
            .thenReturn(Observable.just(successTrueResponse));

Observable observable = mService.verifyReceipt("", "");

observable.subscribe(mMockVerifyReceiptSubscriber);

// Two approaches here

// First one - sleep as much as specified in delay(), in your case 1 second 
// and then perform verification specified on next line

// Second approach (better) - make your architecture in a way, that you can 
// provide an implementation to `repeatWhen()` operator, in other words, 
// inject. And then you'll be able to inject `observable.delay(1, TimeUnit.SECONDS)`
// for production code and inject retry logic without delay for test code.

// Now we are verifying that because of first time `false` was returned,
// then retryWhen() logics are performed
verify(observable).delay(1, TimeUnit.SECONDS); // here should be the injected implementation

verify(mMockVerifyReceiptSubscriber).onNext(eq(Boolean.TRUE));

Now, first time observable will emit false which will call your retryWhen(), next time true will be emitted.

来源：https://stackoverflow.com/questions/43543287/how-to-unit-test-repeatwhen-in-rxjava-server-polling

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java

android

unit-testing

mockito

rx-java