cli process spawning test module

[max-mapper]

for testing cli modules more better we need a module that:

• is designed around use with tape e.g. you pass in a tape test instance
• uses tree-kill to cleanup child processes after the test is done
• uses win-spawn to spawn processes correctly on windows
• has a debug mode where if you do e.g. DEBUG=* npm test it will stream the child process stdout/stderr to the parent stdout/stderr
• lets you choose how to handle child stdout/stderr output in a few different ways
  • buffer all stdout or stderr output (or both)
  • get the first buffer of output from stdout/stderr (one or the other or either)
  • do a e.g. regex match or string indexof against output
• for all of the above it should be impossible for the child processes to become zombies if the tests crash

for reference/inspiration: https://github.com/maxogden/dat/blob/master/test/tests/cli.js#L332

[max-mapper]

@sindresorhus how do you test CLI modules cleanly? know anything that fits our criteria above?

[sindresorhus]

I don't [cleanly]. I've just been lazy using spawning and checking, but this sounds really good. I could definitely use something like this.

Regarding win-spawn: https://github.com/IndigoUnited/node-cross-spawn#why