How does hari and guru test us? How will we know it?
When things are going easily for us in the world, then there is no reason to get angry or dejected. We may think that we are very far advanced and are beyond things like anger, etc. But when we face an undesirable or frustrating situation, then we see our "true colors". In other words, the anger and negativity that was lying just under the surface manifests itself when given the required stimulus. Then we realize that these things still reside within us and we still have more work to do. It is a humbling experience that motivates us to try harder in our sadhana.
At the same time, we may realize that our negative reaction has reduced as compared with before, when given the same negative stimulus. This is a sign that we are making progress and that our heart has purified to some extent. This knowledge inspires us to keep doing more sadhana, because we see that we are moving ahead.
Thus, the difficult situations we face in a day can be seen as challenges or tests set up for us by Hari and Guru. Some may be little tests and some may be big tests, but they are all to humble us and inspire us on our path of devotion.