Jest 承诺返回未定义

Question

My code:

this.apiStore.fetchOrder(id).then(() => {
  alert("Success");
  // TODO - ui updates
})

Jest test:

  describe("order", () => {
    it("fetches the order", () => {
      const fetchOrder = jest.fn();
      const id = 100;
      expect(fetchOrder).toHaveBeenCalledWith(id);
    });
  });

But I am getting the following error:

Cannot read property 'then' of undefined

Any idea on how to fix this?

Edit 1:

Fetchorder api call is defined as follows

fetchOrder = (orderId) => {
    return this.fetch(
      `/api/order.json`,
      {
        method: "POST",
        body: {
          id: orderId
        },
      }
    );
  };

For now i am returning the response as

{"status":"ok"}

if i remove the .then() => {..} then the test is running fine. Any ideas?

Edit 2: The backend code is as follows

def fetch_order
  render json: { status: :ok }
end

Answer 1

fetchOrder 函数不返回 Promise 实例，您应该检查其实现或共享它。