How to use the @jupyterlab/outputarea.OutputAreaWidget.ContentFactory function in @jupyterlab/outputarea

it('should create a gutter widget', () => {
          let factory = new OutputAreaWidget.ContentFactory();
          expect(factory.createGutter().executionCount).to.be(null);
        });

return Kernel.startNew().then(kernel => {
            let factory = new OutputAreaWidget.ContentFactory();
            let options = {
              prompt: 'hello',
              password: false,
              kernel
            };
            expect(factory.createStdin(options)).to.be.a(Widget);
            return kernel.shutdown().then(() => { kernel.dispose(); });
          });
        });