test(name, conf, cb) --> conf is not used ever

[isaacs]

This prevents you from making whole sets of tests skipped, which is insanely convenient:

var isWindows = process.platform !== 'win32'
test('unix stuff', { skip: isWindows }, function(t) {
  // blardeebloop
})

Same for t.test(name, config, cb).

Actually, it looks like the Test class just takes an opts argument, but then doesn't do anything with it, and that argument isn't passed anything any of the places where it's called.