Discussed in https://github.com/Homebrew/brew/pull/1987/files#r100693581. This was originally ommitted because it wasn't compatible with Ruby 1.8. (See https://github.com/Homebrew/legacy-homebrew/pull/48144#r49928971).
super
This will allow us to have global setup and teardown for tests. For example, we can automatically clear caches after each test, to avoid annoying intermittent failures like #1879 and #1886.
test/