How to test jQuery beforeSend method with Jasmine?

Question

I've found out how to test promises in jasmine, but I couldn't find a way to test the beforeSend method.

var xhr = $.ajax({
    url: 'http://example.com',
    type: 'POST',
    data: '...',
    beforeSend: function() {
        methodToBeTested();
    }
});

I do need the code to run before the request is sent so using the always promise is not an option.

Answer 1

Here's my slightly hackie feeling solution but it worked for me.

it('test beforeSend', function() {

    spyOn(window, 'methodToBeTested')

    spyOn($, "ajax").andCallFake(function(options) {

        options.beforeSend();
        expect(methodToBeTested).toHaveBeenCalled();

        //this is needed if you have promise based callbacks e.g. .done(){} or .fail(){}
        return new $.Deferred();
    });

    //call our mocked AJAX
    request()
});

You could also try the Jasmine AJAX plugin https://github.com/pivotal/jasmine-ajax.

Answer 2

You can use this:

if ( $.isFunction($.fn.beforeSend) ) {
//function exists
}

Answer 3

Or you can access the arguments passed on to the spied ajax call later:

$.ajax.calls.argsFor(0)[0].beforeSend();
//instead of argsFor(), you can use first(), mostRecent(), all() ...

This is in case you do not want to have beforeSend() called each time.