Maybe not in a strict sense but knowledge is gathered empirically, thus everything we know is permanently tested by reality.
Reality being defined as what... Space-time?
And tested how, by the limitations of our material senses and/or the instruments we use to extend them?
For that matter, how do we test any definition of reality?
Further you have to determine what is true but how do you accomplish this if there is no compelling evidence that backs it up?
I confess, it's a mystery.
Everything outside of space-time is a guess, from the standpoint of science.
If you want you can define reality as space-time and its properties. We are part of this space-time whether we know all its properties or not. Our limited material senses, brains and instruments are the best tools we have (and to be honest I don't know of any immaterial senses). With these limited senses, brains and instruments we can gather knowledge that is only true with a high probability. We can never obtain absolute certainty as in mathematics.
And no we don't test reality but reality tests us and our knowledge we have about it. These tests can only show that some knowledge is faulty. A good example would be Newtonian mechanics which breaks down at the atomic level. Hence we had to come up with quantum mechanics. But is quantum mechanics absolutely true? We don't know; we only know that it works so far, as good as Newtonian mechanics works in the macroscopic world.
Nature (or reality for that matter) is as it is and not how we want it to be. You can compare reality with the graph of a weird function which we try to approximate with simpler, already known functions and as we zoom in even more details may become visible with which we have to deal then.