JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/jquery.validate.min.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/additional-methods.js"></script>
<form id="myform">
    <input type="checkbox" value="1" name="items[test1]" id="items_test1">
    <input type="checkbox" value="1" name="items[test2]" id="items_test2">
    <input type="submit" />
</form>

CSS

input {
    display: block;
}

JavaScript

// add a class to the checkboxes in the group, here I have added to all
$('[type=checkbox]').addClass('test_checkboxes');

// set up a rule for the class
$.validator.addClassRules("test_checkboxes", {
    require_from_group: [1, ".test_checkboxes"]
});

$("form").validate({
    groups: {
        checkTest: 'items[test1] items[test2]'
    }
});