Unit testing

in JavaScript world

Dmytro Golysh

Agenda:

Why?
Approaches to write Unit tests
Frameworks:
Mocha, Chai, Sinon
Jasmine
Jest
Enzyme
Advanced: Protractor. Cucumber
Live coding: Jasmine, write angular functionality in TDD from scratch
Best practices

Find Software Bugs Early

Simplifies Integration

Provides Documentation

Approaches to write unit tests

Stub everything

describe('CompanyModule:: CompanyHome Component', () => {
    let sut;

    let store;
    let route;

    beforeEach(() => {
        store = jasmine.createSpyObj('store', [
            'dispatch'
        ]);

        route = {
            snapshot: {
                data: {
                    company: {}
                }
            }
        };

        sut = new CompanyHomeComponent(store, route);
    });

Use real dependencies

import { ActivatedRoute } from '@angular/router';
import { Store } from '@ngrx/store';

describe('CompanyModule:: CompanyHome Component', () => {
    let sut;

    beforeEach(() => {
        spyOn(store, 'dispatch');

        sut = new CompanyHomeComponent(Store, ActivatedRoute);
    });

Approaches to write unit tests

Use compiled component Dom as entry point

Enzyme (React)

TestBed (Angular2)

Approaches to write unit tests

Frameworks for unit testing in JavaScript

Enzyme

Jest

Suitable for any UI framework

Chai sinon `should` syntax

describe("A suite is just a function", function() {
  var a;

  it("and so is a spec", function() {
    a = true;

    a.should.be.true;
  });
});

Let's jump to real example

describe("A suite is just a function", function() {
  var a;

  it("and so is a spec", function() {
    a = true;

    expect(a).toBe(true);
  });
});