Documenting running tests in precommit hook

Created by: vivekkalyan

I want a git pre-commit hook that runs test on staged files before commits (similar to this)

This will require access to jest configs such as bail and findRelatedTests.

currently i am running this pre-commit

#!/bin/sh
PASS=true
echo "running tests"
CI=true npm test
if [[ "$?" == 0 ]]; then
    echo "\t\033[32mJest Tests Passed\033[0m"
else
    echo "\t\033[41mJest Tests Failed\033[0m"
    PASS=false
fi

but this results in every single test being run, which takes a long time. i want to effectively run

#!/bin/sh
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep "js$")
if [[ "$STAGED_FILES" = "" ]]; then
    exit 0
fi

PASS=true
echo "running tests"
jest --bail --findRelatedTests $STAGED_FILES
if [[ "$?" == 0 ]]; then
    echo "\t\033[32mJest Tests Passed\033[0m"
else
    echo "\t\033[41mJest Tests Failed\033[0m"
    PASS=false
fi

I believe allowing for this will encourage better practices and am willing to take a stab at it if the maintainers think that it would be useful.

(also open to other solutions that people might use to achieve the same functionality)