I've spent a lot of time reading different books about "good design", "design patterns", etc. I'm a big fan of the SOLID approach and every time I need to write a simple piece of code, I think about the future. So, if implementing a new feature or a bug fix requires just adding three lines of cod...
Requests for tool recommendations are off topic. You may be able to get help on Software Recommendations, but read their help center more carefully than you read SO's before posting! — jonrsharpe35 secs ago