- Are you experimenting with the particular function in REPL/interpreter and then add it to the code?

- How do you debug the code?

- How do you test it, what are the test suits etc?

alias serv="ssh mylogin@myserv.com"

alias work="cd /Users/myname/Sources/mycompany/myproject"

Your point is just for some tiny tiny scenarios of the software you are working on.

You don't need to think about 'how could I write a unit test', you need to think about how could you improve the quality of the code, and unit tests are just one of your tools available to solve this problem.

1. Be sure what you can compile and run the program

2. Have good tools to navigate around the code (I use git grep mostly)

3. Most of the app contain some user or other service interaction - try to get some easy bit (like request for capabilities or some simple operation) and follow this until the end. You don't need a debugger for it - grep/git grep is enough, these simple tools will force you to understand codebase deeply.

4. Sometimes writing UML diagrams works -

- Draw the diagrams (class diagrams, sequence diagrams) of the current state of things

- Draw the diagrams with a proposal of how you would like to change

5. If it is possible, use a debugger, start with the main() function.

[1] https://github.com/Andersbakken/rtags

[2] https://github.com/Golevka/emacs-clang-complete-async