Rocket.Chat/packages/rocketchat-authorization/client/lib/models/Users.js

Meteor.subscribe('scopedRoles', 'Users');

if (_.isUndefined(RocketChat.models.Users)) {
	RocketChat.models.Users = {}
}

RocketChat.models.Users.isUserInRole = function(userId, roleName) {
	query = {
		_id: userId,
		roles: roleName
	};

	return !_.isUndefined(this.findOne(query));
}

RocketChat.models.Users.findUsersInRoles = function(roles, scope, options) {
	roles = [].concat(roles);

	var query = {
		roles: { $in: roles }
	}

	return this.find(query, options);
}