Git pre-commit hook that fails for changes introducing Jest/Jasmine's exclusive tests using "it.only"

pre-commit

#!/bin/sh
# A git pre-commit hook that verifies that the change does not introduce
# the use of a Jest/Jasmine exclusive test via 'it.only(..)', which would
# prevent most other tests from being run without any clear indication thereof

# Redirect output to stderr.
exec 1>&2

ADDED_IT_ONLY=$(git diff -U0 --cached -S"(\W|^)it\.only\s+?\(" --pickaxe-regex | egrep "(^\+.*it.only)|\+{3}")

if [ -n "$ADDED_IT_ONLY" ]; then
    echo "PRE-COMIT CHECK FAILED: You have added calls to it.only(..) thus preventing other tests from running, please fix: $ADDED_IT_ONLY"
    exit 1
fi

Thanks a lot for that simple and elegant solution! I adapted it to my needs. Just out of curiosity the regex you are using doesn't "+?" behave the same way as "*" would have?