how does generation of environment variables, event payloads and various contexts work?

[iamstarkov]

I want to write a test for my GitHub action, which I want to be able to run locally, for that I need make env vars, payloads and context available. That reminded me of act, because you must have solved this problem in order to run arbitrary workflows. I looked into the code and found https://github.com/nektos/act/blob/master/pkg/model/github_context.go.

Does it mean you just generate from scratch and have to update every time GitHub adds new things to it?