Git Pre Commit Hook for ESLint and Jest

pre-commit

#!/usr/bin/env bash
 
 
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep '\.jsx\?$')
BIN_PATH="$(git rev-parse --show-toplevel)/node_modules/.bin"
 
eslint() {
  ESLINT="$BIN_PATH/eslint"
 
  # Check for eslint
  if [[ ! -x "$ESLINT" ]]; then
    printf "\t\033[41mPlease install ESLint\033[0m\n"
    exit 1
  fi
 
  echo "Linting modified files"
 
  echo $STAGED_FILES | xargs $ESLINT
 
  if [[ $? == 0 ]]; then
    printf "\n\033[1;32mLint Passed\033[0m\n"
  else
    printf "\n\033[41mLint Failed:\033[0m Fix lint errors and try again!\n"
    exit 1
  fi
}
 
jest() {
  JEST="$BIN_PATH/jest"
 
  # Check for jest
  if [[ ! -x "$JEST" ]]; then
    printf "\t\033[41mPlease install Jest\033[0m\n"
    exit 1
  fi
 
  echo "Testing related to modified files"
 
  $JEST --bail --findRelatedTests $STAGED_FILES
 
  if [[ $? == 0 ]]; then
    printf "\n\033[1;32mTest Passed\033[0m\n"
  else
    printf "\n\033[41mTest Failed:\033[0m Fix test errors and try again!\n"
    exit 1
  fi
}
 
# Exit if no files modified
if [[ "$STAGED_FILES" = "" ]]; then
  exit 0
fi
 
eslint
jest
 
exit $?

This article shows an arguably better approach, as the use of lint-staged and husky avoids a lot of boilerplate and also means that any user that clones the repo for a project will get the behaviour without having to set up their precommit hooks.

how would this work with coverage threshold? like for commit to fail if test coverage is below certain percentage?

This gist helped me to write a new hook, thank you for sharing it, I really appreciate you doing that!!