test-require-arg feature compatibility

[Dracape]

Make done.fish compatible with test-require-arg feature

For historical reasons, test supports the one-argument form (test foo), and this will also be triggered by e.g. test -n $foo if $foo is unset. We recommend you don’t use the one-argument form and quote all variables or command substitutions used with test.
This confusing misfeature will be removed in future. test -n without any additional argument will be false, test -z will be true and any other invocation with exactly one or zero arguments, including test -d and test "foo" will be an error.
The same goes for [, e.g. [ "foo" ] and [ -d ] will be errors.
This can be turned on already via the test-require-arg feature flag, and will eventually become the default and then only option.

— Fish documentation