Everyone repeats like a mantra that tests are an indispensable element of development work. Is there anything to it? Well, I need to admit that as a developer, I rather often want to skip the test writing stage. I assume I’m not the only one. I’m aware that it’s a mistake, even with testers on board. Effective and efficient testing of your own code can help with catching bugs in new functionalities, as well as in changes to already existing ones. It cannot be questioned. Sometimes tests also help to understand how some long-unused functionality or component works. And that’s a small bonus too. Can a large project cope without testing? Probably so. But the number of errors and their severity will probably be much higher. That’s why in Allegro Ads we pay attention to writing tests.