The test() operator

The RxJava library now has a test() operator which enables internal testing. The operator test() returns an instance of TestSubscriber or TestObserver. We can use the test() operator as shown next:

    public void testOperator() { 
 
      TestSubscriber<Long> test_Subscriber = 
        Flowable.rangeLong(10, 5).test(); 
      TestObserver<Integer> testObserver = 
         Observable.just(12, 89, 67).test(); 
      TestObserver<String> testObserver2 = Single.just("hello").test(); 
      TestObserver<String> testObserver3 = Maybe.just("Mango").test(); 
    } 

The test() operator provides a convenient way to obtain an instance of the TestObserver and TestSubscriber. Now we can assert the obtained result using the instance of the consumers. Let's use it to test Observer as shown by the following code:

    @Test...