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
150
Fluent Conf 2018: Building web apps with Elm Tutorial
jfairbank
2
830
Other Decks in Programming
See All in Programming
自分のために作ったアプリが、グローバルに使われるまで / Indie App Development Lunch LT
pixyzehn
1
160
スモールスタートで始めるためのLambda×モノリス(Lambdalith)
akihisaikeda
2
280
AIコーディングの理想と現実
tomohisa
22
29k
Qiita Bash
mercury_dev0517
2
200
Lambda(Python)の リファクタリングが好きなんです
komakichi
3
200
gen_statem - OTP's Unsung Hero
whatyouhide
1
200
API for docs
soutaro
2
1.3k
タイムゾーンの奥地は思ったよりも闇深いかもしれない
suguruooki
1
670
「影響が少ない」を自分の目でみてみる
o0h
PRO
2
1.1k
ミリしらMCP勉強会
watany
4
760
プロダクト横断分析に役立つ、事前集計しないサマリーテーブル設計
hanon52_
2
440
状態と共に暮らす:ステートフルへの挑戦
ypresto
1
560
Featured
See All Featured
Practical Orchestrator
shlominoach
186
11k
The Illustrated Children's Guide to Kubernetes
chrisshort
48
49k
Keith and Marios Guide to Fast Websites
keithpitt
411
22k
Learning to Love Humans: Emotional Interface Design
aarron
273
40k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
251
21k
Distributed Sagas: A Protocol for Coordinating Microservices
caitiem20
331
21k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
13
670
Java REST API Framework Comparison - PWX 2021
mraible
30
8.5k
Faster Mobile Websites
deanohume
306
31k
The Psychology of Web Performance [Beyond Tellerrand 2023]
tammyeverts
47
2.5k
Designing for humans not robots
tammielis
252
25k
Easily Structure & Communicate Ideas using Wireframe
afnizarnur
194
16k
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