This can be a lot of fun! My "trick" is to write black box test without understanding the code. Like this: 1. Send in some data 2. Observe what data comes out

This can be a lot of fun! My "trick" is to write black box test without understanding the code. Like this: 1. Send in some data 2. Observe what data comes out. 3. Make a test asserting that! 4. Go back to 1.