This is a bit weird sometimes, e.g. to test the return status (that
fish actually *returns $status*), we use a #RUN line with %fish
invoking %fish, so we can use the substitution.
Still much nicer.
The missing scripts are those that rely on config.
This is a nice test (ha!) for how this works and what littlecheck can
do for us.
1. Input is now the actual file, not "Standard Input" anymore. So
any errors mentioning that now include the filename.
2. Regex are really nice for filenames, but especially for line
numbers
3. It's much nicer to have the output where it's created, instead of
needing to follow three files at the same time.
This adds support for .check files inside the tests directory. .check
files are tests designed to be run with littlecheck.
Port printf test to littlecheck and remove the printf.in test.
