How to write a unit test with Jest for code with Promise

I am trying to write a unit test with Jest and Jasmine-pit for the below code and am totally stumped with it. The code is an ajax call which retrieves some data from resource and saves it in the variable.

init = function() {
    var deferred = Q.defer();
    $.ajax({
        type: 'GET',
        datatype: 'json',
        url: window.location.origin + name,
        success: function (data) {
            userId = data.userId;
            apiKey = data.apiKey;
            deferred.resolve();
        }
    });
    return deferred.promise;
},