mocha test for node.js

Please see the arguments of the following Node.js function:

function SearchUser(request) {
            areaInterest =  request.param('areaInterest'),
            searchByName =  request.param('searchByName');
            request.session.searchByName = searchByName;
            request.session.areaInterest = areaInterest;
        if (searchByName !== '' && searchByName !== undefined &&
            (searchByName !== '' && searchByName !== undefined)) {
            query.push(" (c.firstname ~~* '%" + searchByName + "%' or c.lastname ~~* '%" + searchByName + "%')");
        }

        //more logic here
    }

I want to create a unit test framework (mocha) to test the above function. So I created a mocha test as the following:

describe('search', function(){
   describe('#searchRender()', function(){
    it('It should display a user', function(done){
        //create fake request object with parameters ans pass it
        search.SearchUser(null, function (result, err){
               should.not.exist(err);
               should.exists(result);
               done();
           });
    });
   });
});

Instead of passing null values, I have to pass the request object with parameters. How can I create fake request object with parameters and use here instead of null values?