Commands executed during integration testing are executed in a separate
process and thus generate a new result set for each command. To avoid
that these results override each other, they need to have a unique
`command_name`. Derive this name from the test class/name and the index
of the command inside that test, resulting in identifiers like
`IntegrationCommandTests#test_prefix.1 brew --prefix`.
Also replaces `TEST_TMPDIR` in the arguments with `"@TMPDIR@"` to get a
cleaner command identifier that is independent of the temporary
directory that changes with every run.
This is the (partially) documented public API for Homebrew.
The main class you should look at is the {Formula} class (and classes linked from there). That's the class that's used to create Homebrew formulae (i.e. package descriptions). Assume anything else you stumble upon is private.