original.spec.js

describe('##getItemsGroupedByCategory', ()=> {
    it('should receive a callback', ()=> {
      assertFnParams(itemModel.getItemsGroupedByCategory, 1);
    });

    it('should call the callback with the mongoose response', ()=> {
      let callback = function () {};

      mock.schema.aggregate.andReturn(mock.schema);
      mock.schema.match.andReturn(mock.schema);
      mock.schema.sort.andReturn(mock.schema);
      mock.schema.group.andReturn(mock.schema);

      itemModel.getItemsGroupedByCategory.call(mock, callback);
      
      expect(mock.schema.aggregate).toHaveBeenCalled();
      expect(mock.schema.match).toHaveBeenCalledWith(itemModel.getMongooseObjects.match.showable);
      expect(mock.schema.sort).toHaveBeenCalledWith(itemModel.getMongooseObjects.sort.stateType.desc);
      expect(mock.schema.group).toHaveBeenCalledWith(itemModel.getMongooseObjects.group.categoryId);
      expect(mock.handleCallback).toHaveBeenCalledWith(callback, httpStatus.BAD_REQUEST);
    });
  });

proposal.spec.js

describe('##getItemsGroupedByCategory', ()=> {
  //setup
  let callback = function () {};

  mock.schema.aggregate.andReturn(mock.schema);
  mock.schema.match.andReturn(mock.schema);
  mock.schema.sort.andReturn(mock.schema);
  mock.schema.group.andReturn(mock.schema);
  
  //action
  itemModel.getItemsGroupedByCategory.call(mock, callback);
  
  it('should receive a callback', ()=> {
    //assert  
    assertFnParams(itemModel.getItemsGroupedByCategory, 1);
  });
  it('should call the callback aggregate the mongoose response', () => {
      expect(mock.schema.aggregate).toHaveBeenCalled();   
  });
  it('should call the callback schema.match with match.showable', () => {
      expect(mock.schema.match).toHaveBeenCalledWith(itemModel.getMongooseObjects.match.showable);
  });
  it('should call the callback schema.match with match.showable', () => {
      expect(mock.schema.sort).toHaveBeenCalledWith(itemModel.getMongooseObjects.sort.stateType.desc);
  });
  it('should call the callback schema.group with match.showable', () => {
      expect(mock.schema.group).toHaveBeenCalledWith(itemModel.getMongooseObjects.group.categoryId);
  });
  it('should call the callback handleCallback with match.showable', () => {
      expect(mock.handleCallback).toHaveBeenCalledWith(callback, httpStatus.BAD_REQUEST);
  });    
});

proposal2.spec.js

describe('##getItemsGroupedByCategory', ()=> {
  let callback;
  before(() => {
    callback = function () {};
    mock.schema.aggregate.andReturn(mock.schema);
    mock.schema.match.andReturn(mock.schema);
    mock.schema.sort.andReturn(mock.schema);
    mock.schema.group.andReturn(mock.schema);
  });
  
  it('should receive a callback', ()=> {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      assertFnParams(itemModel.getItemsGroupedByCategory, 1);
  });
  it('should call the callback aggregate the mongoose response', () => {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      expect(mock.schema.aggregate).toHaveBeenCalled();   
  });
  it('should call the callback schema.match with match.showable', () => {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      expect(mock.schema.match).toHaveBeenCalledWith(itemModel.getMongooseObjects.match.showable);
  });
  it('should call the callback schema.match with match.showable', () => {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      expect(mock.schema.sort).toHaveBeenCalledWith(itemModel.getMongooseObjects.sort.stateType.desc);
  });
  it('should call the callback schema.group with match.showable', () => {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      expect(mock.schema.group).toHaveBeenCalledWith(itemModel.getMongooseObjects.group.categoryId);
  });
  it('should call the callback handleCallback with match.showable', () => {
      itemModel.getItemsGroupedByCategory.call(mock, callback);
      expect(mock.handleCallback).toHaveBeenCalledWith(callback, httpStatus.BAD_REQUEST);
  });    
});