[jquery] Check if a radio button is checked jquery

I have this HTML:

<input type="radio" name="test" id="test" value="1"><br>
<input type="radio" name="test" id="test" value="2"><br>
<input type="radio" name="test" id="test" value="3"><br>

<input type="button" onclick="CreateJobDo">

When the page loads, none of them will be checked. I want to use jQuery to check if one of the radio buttons is checked when the button is pressed.

I have this:

function CreateJobDo(){
    if ($("input[@name=test]:checked").val() == 'undefined') {

        // go on with script

    } else {

        // NOTHING IS CHECKED
    }
}

But this does not work. How to get it working?

  $('#submit_button').click(function() {
    if (!$("input[@name='name']:checked").val()) {
       alert('Nothing is checked!');
        return false;
    }
    else {
      alert('One of the radio buttons is checked!');
    }
  });

First of all, have only one id="test"

Secondly, try this:

if ($('[name="test"]').is(':checked'))

if($("input:radio[name=test]").is(":checked")){
  //Code to append goes here
}

Something like this:

 $("input[name=test]").is(":checked");

Using the jQuery is() function should work.