Strong pre-commit hook I'm working on.Not done yet, but getting there.

pre-commit

#!/bin/sh

# Rebase commits run in headless branches named with 'no branch'
# If we're in a branch with that name, assume we're rebasing
# If we really want to run checks during rebasing,
# there's a pre-rebase hook available
BRANCH_NAME=$(git branch | grep '*' | grep -c 'no branch')
if [ "$BRANCH_NAME" != "0" ]
then
  exit 0
fi

# Run a program, making sure to use only changes that are staged for commit
# Otherwise, errors could slip through the cracks
# {@link #RESULT} modifies RESULT to the exit status of the given program
runWithStagedFiles () {
  if [[ UNSTAGED_FILES -ne 0 ]]; then
    git stash --quiet --keep-index
  fi
  "$@"
  RESULT=$?
  if [[ UNSTAGED_FILES -ne 0 ]]; then
    git stash pop --quiet
  fi
}

# Check if we need to stash
git diff-files --quiet
UNSTAGED_FILES=$?

# Deploy the safety net
runWithStagedFiles grunt lint
if [[ $RESULT -ne 0 ]]; then
    echo ""
    echo "JSHint detected syntax problems."
    echo "Commit aborted."
    exit 1
fi
echo "--------------------------------------\n"

# Check style guide compliance
STAGED_FILES=$(git diff --cached --name-only -z | tr '\0' ' ')
runWithStagedFiles ./node_modules/.bin/jscs $STAGED_FILES
if [[ $RESULT -ne 0 ]]; then
    echo ""
    echo "Style guide linting failed."
    echo "Commit aborted."
    exit 1
fi
echo "--------------------------------------\n"

runWithStagedFiles grunt lint-templates
if [[ $RESULT -ne 0 ]]; then
    echo ""
    echo "Template linting failed."
    echo "Commit aborted."
    exit 1
fi
echo "--------------------------------------\n"

echo "Checking localizable messages..."
runWithStagedFiles grunt validate-messages
if [[ $RESULT -ne 0 ]]; then
    echo "Commit aborted."
    exit 1
fi
echo "--------------------------------------\n"

echo "Running unit tests."
runWithStagedFiles grunt unit-tests > /dev/null
if [[ $RESULT -ne 0 ]]; then
    echo "Unit test failures."
    echo "Commit aborted."
    exit 1
fi
echo "Unit tests passed.\n"
echo "--------------------------------------\n"

echo "All clear to commit\n"
exit 0

There is still a small problem where using both git stash -k and git stash pop on a file with both staged and unstaged changes will lose the unstaged changes.
Looking for a fix.

Still, it will safely run any validations against the staged commits. This helps guard against committing code that wouldn't pass lint / unit tests.

Taylor what does "$@" do?

"$@" runs all the arguments passed to the function as a command.
So, for example, when runWithStagedFiles grunt lint runs, the $@ becomes grunt lint, and runs like it normally would.