testing grunt-contrib-less with external options

.lessrc

{
  "compile": false,
  "compress": false,
  "noIDs": true,
  "noJSPrefix": true,
  "noOverqualifying": true,
  "noUnderscores": true,
  "noUniversalSelectors": true,
  "zeroUnits": true,
  "strictPropertyOrder": true,
  "stripColors": true,
  "paths": ["../less"]
}

Gruntfile.js

/*
 * grunt-contrib-less
 * http://gruntjs.com/
 *
 * Copyright (c) 2012 Tyler Kellen, contributors
 * Licensed under the MIT license.
 */

'use strict';

module.exports = function(grunt) {

  // Project configuration.
  grunt.initConfig({

    // Configuration to be run (and then tested).
    less: {
      compile: {
        options: {
          lessrc: '.lessrc',
          paths: ['../less']
        },
        files: {
        //  'tmp/individual/*.css': ['test/fixtures/style*.less'],
          'tmp/theme1.css': ['theme1/theme1.less']
        }
      }
    }
  });

  // These plugins provide necessary tasks.
  grunt.loadNpmTasks('grunt-contrib-less');

  // Actually load this plugin's task(s).
 //grunt.loadTasks('tasks');

  // By default, lint and run all tests.
  grunt.registerTask('default', ['less']);

};

less.js

/*
 * grunt-contrib-less
 * http://gruntjs.com/
 *
 * Copyright (c) 2012 Tyler Kellen, contributors
 * Licensed under the MIT license.
 */

'use strict';

module.exports = function(grunt) {

  var path    = require('path');
  var less    = require('less');
  var kindOf  = grunt.util.kindOf;
  var _       = grunt.util._;
  var helpers = require('grunt-lib-contrib').init(grunt);

  var lessOptions = {
    parse: ['paths', 'optimization', 'filename', 'strictImports', 'dumpLineNumbers'],
    render: ['compress', 'yuicompress']
  };

  grunt.registerMultiTask('less', 'Compile LESS files to CSS', function() {
    var done = this.async();

    // Merge task-specific and/or target-specific options with these defaults.
    var options = this.options();

    // Read LESS options from a specified lessrc file.
    if (options.lessrc) {
      options = _.extends(options, grunt.file.readJSON(options.lessrc));
    }

    grunt.verbose.writeflags(options, 'Options');

    // get files
    var files = this.file.src;
    var destFile = this.file.dest;

    if (files.length === 0) {
      grunt.fail.warn('Unable to compile; no valid source files were found.');
      done();
    }

    // hack by chris to support compiling individual files
    if (helpers.isIndividualDest(destFile)) {
      var basePath = helpers.findBasePath(files, options.basePath);
      grunt.util.async.forEachSeries(files, function(file, next) {
        var newFileDest = helpers.buildIndividualDest(destFile, file, basePath, options.flatten);
        compileLess(file, options, function(css, err) {
          if(!err) {
            grunt.file.write(newFileDest, css||'');
            grunt.log.writeln('File ' + newFileDest.cyan + ' created.');
            next(null);
          } else {
            done(false);
          }
        });
      }, function() {
        done();
      });
    } else {
      // normal execution
      var compiled = [];
      grunt.util.async.concatSeries(files, function(file, next) {
        compileLess(file, options, function(css, err) {
          if(!err) {
            compiled.push(css);
            next(null);
          } else {
            done(false);
          }
        });
      }, function() {
        grunt.file.write(destFile, compiled.join('\n'));
        grunt.log.writeln('File ' + destFile.cyan + ' created.');
        done();
      });
    }
  });

  var compileLess = function(srcFile, options, callback) {
    options = grunt.util._.extend({filename: srcFile}, options);
    options.paths = options.paths || [path.dirname(srcFile)];

    var css;
    var srcCode = grunt.file.read(srcFile);

    var parser = new less.Parser(grunt.util._.pick(options, lessOptions.parse));

    parser.parse(srcCode, function(parse_err, tree) {
      if (parse_err) {
        lessError(parse_err);
        callback('',true);
      }

      try {
        css = tree.toCSS(grunt.util._.pick(options, lessOptions.render));
        callback(css, null);
      } catch (e) {
        lessError(e);
        callback(css, true);
      }
    });
  };

  var formatLessError = function(e) {
    var pos = '[' + 'L' + e.line + ':' + ('C' + e.column) + ']';
    return e.filename + ': ' + pos + ' ' + e.message;
  };

  var lessError = function(e) {
    var message = less.formatError ? less.formatError(e) : formatLessError(e);

    grunt.log.error(message);
    grunt.fail.warn('Error compiling LESS.');
  };


};