How to test and get full code coverage on ajax request and it's done and fail callbacks of jQuery ajax request using Jasmine and Blanket.js?

So I have something like this:

var Utils = {};

Utils.genericAddRowPost = function(url) {
    return $.post(url);
};

Utils.genericAddRow = function(dataSource, url) {
    genericAddRowPost(url).done(function(data, textStatus, jqXHR) {
        // add on to dataSource and other stuff
    }).fail(function (jqXHR, textStatus, errorThrown) {
        //handle error
    });
};

I am attempting to test and achieve 100% code coverage using jasmine and blanket, but I can't seem to be able to mock/execute the done and fail handlers. Any help would be greatly appreciated. I would prefer not to have to restructure any of the code posted if possible.

So here is what I did:

it('Verify Utils.genericAddRow', function () {
    var wasSuccessful = false;

    mockObj = {
        data: ko.observableArray([{}])
    };

    // spy on genericAddRowPost that is called inside this test function
    spyOn(Utils, "genericAddRowPost").andReturn({
        done: function (callback) {
            callback({});
            wasSuccessful = true;
            return this;
        },
        fail: function (callback) {
            return this;
        }
    });

    // Call our test function and make first set of expectations
    Utils.genericAddRow(mockObj, 'fakeUrl');
    expect(Utils.genericAddRowPost).toHaveBeenCalledWith('fakeUrl');
    expect(wasSuccessful).toBeTruthy();

    // Override original spy implementations
    Utils.genericAddRowPost().done = function (callback) {
        return this;
    };
    Utils.genericAddRowPost().fail = function(callback) {
        callback(null, null, 'testError');
        wasSuccessful = false;
        return this;
    };

    // Call our test function and make second set of expectations
    Utils.genericAddRow(mockObj, 'anotherFakeUrl');
    expect(Utils.genericAddRowPost).toHaveBeenCalledWith('anotherFakeUrl');
    expect(wasSuccessful).toBeFalsy();
});

I will edit my question to reflect that genericAddRow and genericAddRowPost are both functions that live on a Utils object literal.