// use with https://www.npmjs.org/package/deep-diff

toEqualObj: function () {
  var KINDS = {
    'N': 'newly added property/element',
    'D': 'property/element was deleted',
    'E': 'property/element was edited',
    'A': 'change occurred within an array'
  };

  function formatDiff(objdiff) {
    return objdiff.map(function (diff) {
      return '\t'+diff.kind +' at '+ diff.path.join('.') +'\n'+
             '\t'+diff.actual +' should be '+ diff.expected;
    }).join('\n\n');
  }

  return {
    compare: function (actual, expected) {
      var objdiff = (deepDiff(expected, actual) || []).map(function (diff) {
        return {
          kind: KINDS[diff.kind],
          path: diff.path,
          expected: diff.lhs,
          actual: diff.rhs
        };
      });

      return {
        pass    : objdiff.length === 0,
        message : 'Expected object not to have differences\n\n' + formatDiff(objdiff)
      };

    }
  };
}