Testing

How to test our model reducer?

Testing functions of models is easy, since we just have to import the model in a file and test it.

But testing the reducer of a particular model is harder. For that iceCream provides a function getArrayFromModelReducers that take, as arguments, the modelname and the reducers object of your model and returns an array of all your reducers of the model you are testing. With the library reduce-reducers you can create a reducer and test it to see if it mutates the state as desired:

import reduceReducers from "reduce-reducers";
import { getArrayFromModelReducers } from "icecream-please";
import counterModel from "./counter";

const { modelname, state, reducers } = counterModel;

describe("Reducers of counter model...", () => {
  const reducer = reduceReducers(
    state,
    ...getArrayFromModelReducers(modelname, reducers)
  );
  test("should increment the counter", () => {
    expect(reducer(state, { type: "counter/add" })).toEqual({ number: 1 });
  });
  test("should decrement the counter", () => {
    expect(reducer({ number: 3 }, { type: "counter/sub" })).toEqual({
      number: 2
    });
  });
  test("should reset the counter", () => {
    expect(reducer({ number: 5 }, { type: "counter/reset" })).toEqual({
      number: 0
    });
  });
});