TypeError: expect(...).toEqual is not a function

Question

I am following Dan Abramov's tutorial on Redux. (https://egghead.io/lessons/javascript-redux-avoiding-object-mutations-with-object-assign-and-spread)

In lesson's 9 he introduces testing and using expect and .toEqual()

This is my code:

var expect = require('chai').expect;
var freeze = require('deep-freeze-node');

const testToggleTodo = () => {
    const todoBefore = {
        id: 0,
        text: 'Learn Redux',
        completed: false
    };

    const todoAfter = {
        id: 0,
        text: 'Learn Redux',
        completed: true
    };

    expect(
        toggleTodo(todoBefore)
        ).toEqual(todoAfter)
}

testToggleTodo();
console.log('All tests passed.')

and I keep getting an error:

.../react_redux/src/a.js:24
        ).toEqual(todoAfter)
          ^

TypeError: expect(...).toEqual is not a function

What am I doing wrong? I am copying his code verbatim, but it leads to errors.

Answer 1

For me, my .toEqual was following the wrong brackets. Make sure it's expect(...).toEqual(..), and not expect(...(...).toEqual(...))

Answer 2

in my case to make it work I done following:

1. npm install --save expect                                install package from npm
2. import expect from 'expect';                             import lib in file
3. expect(toggleTodo(stateBefore, action)).toEqual(stateAfter);

Answer 3

Not sure if the provided syntax was ever correct for the chai library. (I would assume they are using some other assertion library)

The way the equality should be checked with its expect function is

expect(toggleTodo(todoBefore)).to.equal(todoAfter);

References:

• http://chaijs.com/api/bdd/#method_equal