Simplify running a single test (or even a single method from a single
test), which is useful when developing or debugging a test. Instead of
`brew test TEST=test_diagnostic.rb TESTOPTS=--name=test_check_DYLD_vars`
it is now possible to run `brew tests --only=diagnostic/check_DYLD_vars`
to get the same effect. Similarly, `brew tests --only=diagnostic` maps
to `brew test TEST=test_diagnostic.rb`.
ClosesHomebrew/homebrew#48279.
Signed-off-by: Martin Afanasjew <martin@afanasjew.de>
This parameter is printed by every `brew tests` run and feeding it back
into the test suite allows to get an identical run. Make it easier to
do that by accepting the argument as it is printed during `brew tests`.
This requires a slight adjustment to named-argument passing as the
number that follows `--seed` is also seen as a named argument, but we
usually only want to pass `TEST=<something>` and `TESTOPTS=<something>`.
Some tests, that construct a Git repository for testing, will silently
fail if the global Git user isn't properly set up. There are valid use
cases for this, thus use a fixed commit author/committer for all tests
instead of relying on the user's configuration.
