pre-commit hook to check mailmap

.pre-commit-config.yaml

---
# Configure various overrides and exceptions in this file.
# See https://pre-commit.com/ for details.

fail_fast: false

repos:
  - repo: local
    hooks:
      - id: check-mailmap
        name: Detect if an email address needs to be added to mailmap
        language: script
        entry: ./check-mailmap
        always_run: true
        exclude: .*

check-mailmap

#!/bin/sh
if [ -n "${DEBUG}" ]; then
  set -x
fi

# Global return code.
RC=0

main() {
  check_email
}

check_email() {
  # Check if any email address is associated with more than one name.
  #
  # Example:
  #   John Doe <jdoe@example.com>
  #   jdoe <jdoe@example.com>
  #
  # The above example can be fixed by adding these two lines to .mailmap file:
  #   John Doe <jdoe@example.com> John Doe <jdoe@example.com>
  #   John Doe <jdoe@example.com> jdoe <jdoe@example.com>
  #   ^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  #   How we want it to appear    How it appears in git commit
  #
  # See git-shortlog(1) for more details.
  output="$(! 2>&1 git log --use-mailmap --pretty='%aN %aE' | tr '[:upper:]' '[:lower:]' | sort -u | awk '{print $NF}' | sort | uniq -c | sed -e 's/^[ \t]*//' | grep -v '^1[[:space:]]' | awk '{print $NF}')"

  if [ -n "${output}" ]; then
    RC=1
    echo 'The following email addresses are associated with more than one name:'
    echo
    for email in ${output}; do
      echo "        ${email}"
    done
    echo
    echo 'The associations include:'
    for email in ${output}; do
      echo
      git log --pretty='%aN <%aE>' --regexp-ignore-case --author="${email}" | sort | uniq -c
    done
  fi
}

main
exit ${RC}

for a good condition

$ pre-commit run check-mailmap --all-files --verbose
[check-mailmap] Detect if an email address needs to be added to mailmap.......................Passed

for a bad condition

$ pre-commit run check-mailmap --all-files --verbose
[check-mailmap] Detect if an email address needs to be added to mailmap.......................Failed
hookid: check-mailmap

The following email addresses are associated with more than one name:

        jdoe@example.com
        billy.bob@example.com

The associations include:

     13 John Doe <jdoe@example.com>
      4 jdoe <jdoe@example.com>

      2 Billy Bob <billy.bob@example.com>
      2 Bubba <billy.bob@example.com>

I've added this hook to https://github.com/jumanjihouse/pre-commit-hooks#check-mailmap

Update .pre-commit-config.yaml to include:

---
- repo: https://github.com/jumanjihouse/pre-commit-hooks
      sha: 1.8.0
      hooks:
        - id: check-mailmap