The checkout action will clone your repo into the
GITHUB_WORKSPACE directory so if you need to grab the source code of something in the current project or wish to work with git directly, this action will need to be used.
- uses: actions/checkout@v1
In software projects, you may wish to test your codebase on multiple versions of a particular language. These set of actions install a specified version of the language and have it setup into the PATH so it is immediately available on the system. Currently, NodeJS, Java, .NET, Elixir, Python, Ruby, and Go are all supported which should give ample support for most software projects
Here's an example of the setup-node action:
- name: Install NodeJS 10.x