TL;DR
At software testing conferences, lean coffees, there is always at least one post-it about how to start with test framework automation. With open-source software at your disposal through Github, to start is easier than ever before. The post is based on a remarkable book written by Chad Fowler, The Passionate Programmer.
An important part of being a passionate software tester is to know how to use the testing framework. The quickest way to learn something is to:
- get your keyboard dirty
- have a mentor
You first have to choose a programming language. My recommendation is Ruby, Python, and Elixr. Reason? Those languages have excellent testing framework support. Ruby, for example, has a Rspec framework. It was so well accepted by Ruby community that there is Elixr counterpart for Rspec, Espec.
When you have a language lock, find some popular open-source framework written in that language on Github. Read README.md and clone that repo and run tests. Examine the code coverage report. If the framework does not include code coverage, learn how to add one. You will also learn which is the best code coverage library for your programming language.
Find the part of code that is not covered or with low coverage and add a test for it. Maybe that part of code is hard or none testable. You will learn from the example what really means none testable code.
When stuck, ask for help in Github repo, the author put help instructions in README.MD file. The great thing about Github is when your commit is accepted, you are automatically listed under repository contributors. This means that your code is released, and you can put that in your CV.