Unit test – how to simulate the improved service observable that calls onerror?

I'm testing this code

service.getProducts()
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Subscriber<Result<Catalog<SoajsProductPreview>>>() {

                @Override
                public void onError(Throwable e) {
                    view.showErrorView(e);
                }

                @Override
                public void onNext(Result<Product>  products) {
                   view.showProducts(products)
                }

                @Override
                public void onCompleted() {}
            });

Test view Showproducts() simulates whether the result returned by the service is normal@ H_ 419_ 14 @ I do

when(service.getProducts().thenReturn(someObservable);

Now I want to test the view Showerrorview() is called when the service throws an error, but I can't find a way:

Obviously, the following is not compiled

when(service.getProducts().thenReturn(someException);

This throws an exception immediately, but does not call the subscriber's onerror method

when(service.getProducts().thenReturn(someException);

How to call subscriber onError()？

Solution

when(service.getProducts().thenReturn(Observable.error(someException))

when(service.getProducts().thenReturn(Observable.error(someException))

It should work See the documentation starting here