– Before you start trying to implement the skills and practices discussed in this site, try some tests to make sure you fully understand them.
Alternatively, you can take the tests to help you know what you need to understand.
Either way, the idea is to validate your assumptions, and get quick feedback on where you are going. Better to take the test and fail quickly, than to implement some ideas and find out it made things worse.
Tests for SOLID
https://www.flexiquiz.com/SC/N/bcbc850d-a6ee-4d76-940a-d016cffac68b
(Accepting pull requests for new tests)