Test and stub params in POST request

Guys how can I stub params in POST request, for example here a part of function

 gridCalculator : function(req,res){
        // calculation logic
        var options=[];
        options.dateFirstLicensed = req.param('DateFirstLicensed');
        options.dateFirstInsured = req.param('DateFirstInsured');
        options.claimList = req.param('ClaimList');
        options.suspenList = req.param('SuspenList');

...etc

if I did this

  it('grid Calculate', function (done) {
    var req = {
     'DateFirstLicensed' : "01-01-2010",
   'DateFirstInsured': "01-01-2011",
   'ClaimList': ['05-03-2012'],
   'SuspenList': [{'StartDate':'05-03-2012','EndDate':'05-05-2012' }]
    };
    gridCalculator.gridCalculator(req,function (err, result) {
      result.should.exist;
      done();
    });
  });

I get error because I'm simply passing an object not POST request

 TypeError: req.param is not a function