Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
JazzCon 2018: Effective React Testing
Search
Jeremy Fairbank
March 22, 2018
Programming
1
340
JazzCon 2018: Effective React Testing
Jeremy Fairbank
March 22, 2018
Tweet
Share
More Decks by Jeremy Fairbank
See All by Jeremy Fairbank
Connect.Tech 2020: Advanced Cypress Testing
jfairbank
1
190
CodeMash 2020: Solving the Boolean Identity Crisis
jfairbank
1
140
CodeMash 2020: Practical Functional Programming
jfairbank
1
310
Connect.Tech 2019: Practical Functional Programming
jfairbank
0
340
Connect.Tech 2019: Solving the Boolean Identity Crisis
jfairbank
0
170
Lambda Squared 2019: Solving the Boolean Identity Crisis
jfairbank
0
120
All Things Open 2018: Practical Functional Programming
jfairbank
2
260
Connect.Tech 2018: Effective React Testing
jfairbank
1
140
Fluent Conf 2018: Building web apps with Elm Tutorial
jfairbank
2
830
Other Decks in Programming
See All in Programming
Day0 初心者向けワークショップ実践!ソフトウェアテストの第一歩
satohiroyuki
0
780
リアクティブシステムの変遷から理解するalien-signals / Learning alien-signals from the evolution of reactive systems
yamanoku
2
1.2k
Being an ethical software engineer
xgouchet
PRO
0
180
CRE Meetup!ユーザー信頼性を支えるエンジニアリング実践例の発表資料です
tmnb
0
580
Boost Your Performance and Developer Productivity with Jakarta EE 11
ivargrimstad
0
780
AHC 044 混合整数計画ソルバー解法
kiri8128
0
320
アーキテクトと美学 / Architecture and Aesthetics
nrslib
12
3.2k
ベクトル検索システムの気持ち
monochromegane
30
9.6k
SLI/SLOの設定を進めるその前に アラート品質の改善に取り組んだ話
tanden
2
790
Going Structural with Named Tuples
bishabosha
0
190
Vibe Codingをせずに Clineを使っている
watany
15
5k
PHPUnit 高速化テクニック / PHPUnit Speedup Techniques
pinkumohikan
1
1.3k
Featured
See All Featured
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
17
1.1k
Building Flexible Design Systems
yeseniaperezcruz
328
38k
Understanding Cognitive Biases in Performance Measurement
bluesmoon
28
1.6k
Unsuck your backbone
ammeep
670
57k
The Cost Of JavaScript in 2023
addyosmani
48
7.6k
Put a Button on it: Removing Barriers to Going Fast.
kastner
60
3.8k
The Psychology of Web Performance [Beyond Tellerrand 2023]
tammyeverts
46
2.4k
How to Think Like a Performance Engineer
csswizardry
22
1.5k
Learning to Love Humans: Emotional Interface Design
aarron
273
40k
Producing Creativity
orderedlist
PRO
344
40k
XXLCSS - How to scale CSS and keep your sanity
sugarenia
248
1.3M
Measuring & Analyzing Core Web Vitals
bluesmoon
6
370
Transcript
Effective React Testing Jeremy Fairbank @elpapapollo
@testdouble helps improves how the world build software. testdouble.com/agency
In beta now! bit.ly/programming-elm
My shiny new React application…
…without tests.
None
None
API Design
Refactoring
?
redux-thunk +
Components Test expected output.
Reducer Test state changes as expected.
Actions Test actions through reducer tests. Test thunks for coordination.
E2E Integration Unit Snapshot $$$ $
E2E Integration Unit Snapshot $$$ $
E2E Integration Unit Snapshot $$$ $
E2E Integration Unit Snapshot $$$ $
E2E Integration Unit Snapshot $$$ $
None
Jest facebook.github.io/jest
1. Automatic with create-react-app 2. Or add yourself: yarn add
jest npm install --save jest
Enzyme JavaScript testing utilities for React. github.com/airbnb/enzyme yarn add enzyme
enzyme-adapter-react-16
TDD with Components <NameTag name="Jeremy" employer="Test Double" /> expect "Hello.
I'm Jeremy from Test Double."
DEMO
Unit Tests Recap
Unit Tests Recap
Unit Tests Recap Easy to write
Unit Tests Recap Easy to write Fast
Unit Tests Recap Easy to write Fast Isolated design feedback
Unit Tests Recap Easy to write Fast Isolated design feedback
Unit Tests Recap Easy to write Fast Isolated design feedback
Tedious to test all components
Unit Tests Recap Easy to write Fast Isolated design feedback
Tedious to test all components Coupled to implementation
Unit Tests Recap Easy to write Fast Isolated design feedback
Tedious to test all components Coupled to implementation No interaction with other components
Snapshot Tests Recap
Snapshot Tests Recap
Snapshot Tests Recap Easily test component tree
Snapshot Tests Recap Easily test component tree Fast
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly Regression safety
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly Regression safety
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly Regression safety No design feedback
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly Regression safety No design feedback Break from markup changes
Snapshot Tests Recap Easily test component tree Fast Fill in
test gaps quickly Regression safety No design feedback Break from markup changes Prone to human error
Integration Tests Recap
Integration Tests Recap ⚙⚙
Integration Tests Recap ⚙ Test component’s interaction with child components
⚙
Integration Tests Recap ⚙ Test component’s interaction with child components
⚙
Integration Tests Recap ⚙ Test component’s interaction with child components
Coupled to child component implementation ⚙
Integration Tests Recap ⚙ Test component’s interaction with child components
Coupled to child component implementation Redundant test coverage ⚙
Integration Tests Recap ⚙ Test component’s interaction with child components
Coupled to child component implementation Redundant test coverage Harder to debug ⚙
E2E Integration Unit Snapshot $$$ $
E2E Integration Unit Snapshot $$$ $
Reducer Action New State State Testing Redux
DEMO
Unit Tests “Redux”
Unit Tests “Redux”
Unit Tests “Redux” Easier to write Fast Isolated design feedback
Unit Tests “Redux” Easier to write Fast Isolated design feedback
Unit Tests “Redux” Easier to write Fast Isolated design feedback
Thunk tests coupled to implementation
Unit Tests “Redux” Easier to write Fast Isolated design feedback
Thunk tests coupled to implementation No interaction with the rest of the application
Integration Tests “Redux”
Integration Tests “Redux” ⚙⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together ⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together Test entire application ⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together Test entire application ⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together Test entire application More setup ⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together Test entire application More setup Harder to debug ⚙
Integration Tests “Redux” ⚙ Test reducer, actions, and API library
together Test entire application More setup Harder to debug Doesn’t test user interaction ⚙
End-to-end Testing
Test entire application in browser End-to-end Testing
Test entire application in browser Simulate user interactions End-to-end Testing
Test entire application in browser Simulate user interactions Interact with
a real API (with test data) End-to-end Testing
Test entire application in browser Simulate user interactions Interact with
a real API (with test data) Focus on happy path End-to-end Testing
yarn add cypress
DEMO
E2E Tests Recap
E2E Tests Recap
E2E Tests Recap Test all pieces working together in user
scenarios
E2E Tests Recap Test all pieces working together in user
scenarios Cypress makes E2E pleasant and easier to debug
E2E Tests Recap Test all pieces working together in user
scenarios Cypress makes E2E pleasant and easier to debug
E2E Tests Recap Test all pieces working together in user
scenarios Cypress makes E2E pleasant and easier to debug Slow
E2E Tests Recap Test all pieces working together in user
scenarios Cypress makes E2E pleasant and easier to debug Slow Break from markup changes or pepper source code with identifiers
E2E Tests Recap Test all pieces working together in user
scenarios Cypress makes E2E pleasant and easier to debug Slow Break from markup changes or pepper source code with identifiers Still harder to debug than unit tests
E2E Integration Unit Snapshot $$$ $
Snapshot E2E Integration Unit $$$ $
Write tests!
Thank you! Jeremy Fairbank @elpapapollo Slides: bit.ly/react-testing-jazzcon Code: bit.ly/react-testing-jazzcon-code