When using the quiet mode, nothing is printed to stdout.
This may be useful in automation, when only the exit status will tell if the tests have passed or not:
> ./doctest.fish --quiet docs/include/one-ok.md; echo $status
0
> ./doctest.fish --quiet docs/include/one-fail.md; echo $status
1
Note that even in the quiet mode, error messages are still shown:
> ./doctest.fish -q /
doctest.fish: Error: input file is a directory: /