Writing and running full e2e integration tests using Go and for Go CLI applications. Lookingo into one of:
@firstname.lastname@example.org or @email@example.com Can I get your thoughts and opinions on any of these three options for testing CLI apps written in Go with the possibility of also measuring coverage – Which means using the test binary under test which I think all three solutions can do? (definitely the first one says it can).
Quickly tried out testcli and it’s a “no go” for me:
- Its README is out-of-date and has an old reference to a package that had its import path changed (easily fixed)
- Running the tests failed miserably as it could not find the
greetingbinary in the
da fuq?! I guess this doesn’t do what I thought – which is to build the test binary and use that to run CLI tests against so you can actually measure coverage 😔
This is eventually what I came up with so far… What do you think @firstname.lastname@example.org ? 🤔
@email@example.com Haven’t used them so far, either, sorry. 🤔
@firstname.lastname@example.org Yeah I actually use this technique a lot in GoNix for basically all the Applets. I think this makes it easier to test. The
cmdtest package is kind of cool though really, it basically implements the same kind of test runner as you may (or may not) have seen in the Mercurial test suite. The test files in
testdata are essentially text files that look a bit like you’ve run something on the console and copied pasted them. This is brilliant for e2e cli integration testing 👌 And yes it manages to run the test binary so that coverage can also be measured which is fantastic 👌 – Of course this does not preclude you from writing unit tests for any other parts of your package/library that have a public facing API – But if your public facing API is just the CLI then this is a perfect fit 👌
@email@example.com Oh btw… The reason a
io.Writer is left out for “stderr” is that normally I tend to just set the logging output to
log.SetOutput(os.Stderr) anyway and its not usually something I end up testing. Not sure if this is the best approach, but I’m only really interested in testing the “output”(s) and either error or non-error cases.
@firstname.lastname@example.org Yes a long time ago
@email@example.com Yeah I agree errors should be tested too. That’s why
Main() has the
func Main(w io.Writer, args string) error 😅 So you can actually assert on the
error returned. For a CLI however, I’m not particularly a fan of logging errors to stderr too much (if at all). And re
go-cmdtest FWIW a Terminal combines stdout and stderr too by default when displaying the output of a program 😅 – However I filed an issue against the cmdtest project and now I’m not so sure I want to continue using it, I may as well just figure out how to run the test binary under coverage and write the tests myself in Go.
@firstname.lastname@example.org Hmmm good points but yeah it depends on the program 👌