I have an app that I built recently the repo. Its even live on the play store but I'm worried that there's not even a single test written for it. Even unit tests will bring peace to my heart and the problem is...ever since I've started android development, I've never had to write tests, web dev included.

In my defence: I'm self taught, I have about 4 years of experience in both web and android development and with most resources I use, its about solving a problem, and rerunning a piece of code always made me feel like I'm testing it already and I pass.

This is a very bad habit apparently and it makes me doubt myself as a developer. I'd really appreciate a heads up of any sort, whether a reply here, link to resources or a pull request as a jump start. Thank you