Keir BowdenCTO, BrightGen

@bob_buzzard

Unit Testing Lightning ComponentsWith Jasmine

Keir Bowden@bob_buzzard

CTO, BrightGen

PLACE COMPANY LOGO HERE

Introduction

● Give confidence

● Reduce cost of bugs

● Produce Testable Code

● Promote refactoring

Why Write Unit Tests

JavaScript Testing on Salesforce

● No test context for client

○ Changes aren't rolled back

● Side effects

○ DOM manipulation

○ Server side actions

● You don't have to!

Challenges

Techniques

● Use unobtrusive JavaScript

● Avoid anonymous functions

○ Can't test in isolation

○ Have to execute action

Write Testable Code

Techniques

● Decompose functions

○ Function to decide on action

○ Function to execute the action

Write Testable Code

Demo App

Github repository

http://bobbuzz.me.uk/UTLCJSM

Job Board

Jasmine

Jasmine

● Pure JavaScript testing framework

● Executes in-browser

○ Execute tests from anywhere

○ Lightning Component JavaScript only executable from browser

● Open source : http://bobbuzz.me.uk/2bVjTEr

● Minor changes for locker service

Overview

Jasmine

● Behaviour-driven development testing framework

○ Given the job page is openWhen the user searches for jobsThen the search method should be invoked

● Also known as Setup (Given) - Exercise (When) - Verify (Then)

Overview

Jasmine

● Suite

○ Collection of tests○ describe function

● Spec

○ Single test○ it function

● Expectation

○ Verifies behaviour (equivalent of assert in Apex)○ expect function○ Chained with matcher function

Features

Jasmine

● Setup/Teardown

○ beforeAll - called once, before first spec○ afterAll - called once, after last spec○ beforeEach - called before each spec○ afterEach - called after each spec

● Spies

○ Stubs function○ Tracks calls○ Tracks arguments

Features

JasmineSpies

Reset when spec/suite completes

doSearch function calls getJobs

getJobs executes server side action

spy on the getJobs functionJasmine spy code replaces getJobs implementation - no server side action

interrogate spy to confirm behaviour

Jasmine

● Object with functions to handle Jasmine events

○ e.g. JasmineStarted, specStarted, specDone

● HTML reporter included

○ Disabled in the github repository○ Replaced with SLDS version

● Console reporter available

○ But deprecated!

Reporter

Testing Lightning Components

Locker Service

● Delete from Jasmine JavaScript:

● Can't spy framework methods

How to Trigger Tests?

TestApplication

ReporterComponent

JasmineTestable

Component

1 create

2 Initialise

5 queue tests

6 queue tests

4 Initialised

7 tests queued

8 execute

9 notify

10 Complete

3 register

Lightning component

Jasmine

Lightning event

Attribute change event

JavaScript function

Key

Triggering Tests

1. The test application creates the Jasmine instanceThe Jasmine instance is visible to all components in the same namespace.This includes all testable components.

2. The application fires an event asking the reporters to initializeThis is an application event that can be received by any component with an appropriate handler

3. Each reporter registers an object to receive notifications with JasmineThe object can take action on each event, but my samples simply capture the information as the tests progress and then take action once all are complete.

4. Each reporter fires an event to indicate it has completed initialization

5. Once all reporters have initialised, the application fires a queue tests eventThe application knows how many responses to expect.

Triggering Tests

6. Each testable component receives the event and queues their tests with JasmineThe tests are not run at this point!

7. Each testable component fires an event to indicate it has queued its testsThe test application knows how many responses to expect.

8. The test application invokes the Jasmine execute methodThis executes the queued tests

9. As tests execute, they notify the reporter(s) of the outcomesThe sample reporters record this information but take no action

10. The application notifies the reporter(s) that all tests are completeThe sample reporters take appropriate action once all tests are complete.Posting to chatter, for example.

Key Takeaways

● Front end code deserves unit tests

● Decompose functions

● Isolate framework calls

● It's probably not the locker service!

Useful LinksJasmine source

https://github.com/jasmine/jasmine

Jasmine introductionhttp://jasmine.github.io/2.4/introduction.html

Jasmine JavaScript Testing (Book)https://www.packtpub.com/web-development/jasmine-javascript-testing-second-edition

Jasmine Reportershttps://github.com/larrymyers/jasmine-reporters

Thank Y u