validate-commit-msg.js

#!/usr/bin/env node

/**
 * Git COMMIT-MSG hook for validating commit message
 * See https://docs.google.com/document/d/1rk04jEuGfk9kYzfqCuOlPTSJw3hEDZJTBN5E5f1SALo/edit
 *
 * Installation:
 * >> cd lx-helpers
 * >> ln -s validate-commit-msg.js .git/hooks/commit-msg
 */
var fs = require('fs');
var util = require('util');


var MAX_LENGTH = 200;
var PATTERN = /^(?:fixup!\s*)?(\w*)(\(([\w\$\.\-\*/]*)\))?\: (.*)$/;
var IGNORED = /^WIP\:/;
var TYPES = {
    feat: true,
    fix: true,
    docs: true,
    style: true,
    refactor: true,
    test: true,
    chore: true,
    revert: true
};


var error = function() {
    // gitx does not display it
    // http://gitx.lighthouseapp.com/projects/17830/tickets/294-feature-display-hook-error-message-when-hook-fails
    // https://groups.google.com/group/gitx/browse_thread/thread/a03bcab60844b812
    console.error('INVALID COMMIT MSG: ' + util.format.apply(null, arguments));
};


var validateMessage = function(message) {
    var isValid = true;

    if (IGNORED.test(message)) {
        console.log('Commit message validation ignored.');
        return true;
    }

    if (message.length > MAX_LENGTH) {
        error('is longer than %d characters !', MAX_LENGTH);
        isValid = false;
    }

    var match = PATTERN.exec(message);

    if (!match) {
        error('does not match "<type>(<scope>): <subject>" ! was: ' + message);
        return false;
    }

    var type = match[1];
    var scope = match[3];
    var subject = match[4];

    if (!TYPES.hasOwnProperty(type)) {
        error('"%s" is not allowed type !', type);
        return false;
    }

    // Some more ideas, do want anything like this ?
    // - allow only specific scopes (eg. fix(docs) should not be allowed ?
    // - auto correct the type to lower case ?
    // - auto correct first letter of the subject to lower case ?
    // - auto add empty line after subject ?
    // - auto remove empty () ?
    // - auto correct typos in type ?
    // - store incorrect messages, so that we can learn

    return isValid;
};


var firstLineFromBuffer = function(buffer) {
    return buffer.toString().split('\n').shift();
};



// publish for testing
exports.validateMessage = validateMessage;

// hacky start if not run by jasmine :-D
if (process.argv.join('').indexOf('jasmine-node') === -1) {
    var commitMsgFile = process.argv[2];
    var incorrectLogFile = commitMsgFile.replace('COMMIT_EDITMSG', 'logs/incorrect-commit-msgs');

    fs.readFile(commitMsgFile, function(err, buffer) {
        var msg = firstLineFromBuffer(buffer);

        if (!validateMessage(msg)) {
            fs.appendFile(incorrectLogFile, msg + '\n', function() {
                process.exit(1);
            });
        } else {
            process.exit(0);
        }
    });
}