Pre-commit git hook to avoid committing non-formatted Go code

pre-commit

#!/bin/sh

gofiles=$(git diff --cached --name-only --diff-filter=ACM | grep '.go$')
[ -z "$gofiles" ] && exit 0

unformatted=$(gofmt -l $gofiles)
if [ ! -z "$unformatted" ]; then
  echo "Go files must be formatted with gofmt. Please run:" >&2
  for fn in $unformatted; do
    echo "  gofmt -w $PWD/$fn" >&2
  done

  exit 1
fi

exit 0

Place this into .git/hooks/pre-commit and make it executable.