Testing 101
Or that time i got way too obsessed with testing a package I was building
Hew
@hewIngram
THE BASICS
Avoid bugs
Ensure functionality works
Safely deploy anytime
Reliable, predictable code
Better code?
E2E
Integration
Unit
Linting
Linting
Find possible logic errors
Promote best practice
Promote stylistic consistency
Pssst...
Fail fast
Zero setup
(basically)
Great configs to start with
Customizable
🎉
Accessibility + security
File by file
🤮
Annoying to introduce in legacy codebases
Unit
E2E
Integration
Unit
Linting
Should return 'apples' if inputAnimal is hippo
Should return null if inputAnimal is not in animalConfig
Snapshot tests mean I don't need unit tests anymore... right?
Fast to run
Easy setup
🎉
Promotes good code
Fast to build
Tests only a single function
🤮
Can be fragile
Not all code is unit testable
E2E
Integration
Unit
Linting
More real
Slower
Harder to build
Integration
Closer to 'real' usage
Great as code/team grows
🎉
Hard to setup
🤮
Errors can be hard to pinpoint
Slower to run
E2E
Super real
Tests loads of things at once
🎉
Getting easier to write
SO SLOW
🤮
Hard setup
(historically)
Brittle
Can be hard to find root cause if there are errors
Linting
Unit tests
Integration
End to End
✅
✅
Mutation
E2E
Integration
Unit
Linting
Fuzz testing
F̷̢̧̧̧̧̛͓͚̦̼̺̝̝̞̱̦̟̘͍͈͈͕̩̼̣̩̠͍̥̤̤̹̦̝̺̼͓̤̯̱̳͎͚̺͔̯̯͕͓̝̯͎͔̱̯͖͖̞̊̈́̓̈̒͊̈́̿̀̀̌̈̀̏̄̿̃͗̈́̉̉̆̐̌̒͑̔͑̿̈́̏̾̌͌̏̓̿̐̅̓͗̄̂͌̂̂̂̋͂̈́̄̾̆̐̐̀̈́̀̅̿̑̇̎̿̐̒́̿́͒͗̽̓͒͐̋̍͋̕͘̚͘̚͠͝ͅư̴̢̧̨̨̡̛̬̣͎͔̗̬͖̟̠̤̹͖͙̺̻̹̼̦̬͈̟̰͔̟̹̟̭͉̝̳̩͓̦̙̰͔̣̱͙̣͓͓̻̱̪͓̤̭͙̞̫̗̭̯̖͙̱̠͉̖̺̪̰̬̺͉̝̜̠͎͕̪̭͎͎͖̼͎͇̲̝̰̣͋̾͐͛̃̓́̓͜͜͜͜ẕ̴̨̧̨̡̨̡̰̟̲͔̱͍̬͈̲̬͖̟̦̭̳̣͓̣̖̙̩̺̤̭͓̫͔̬̰̮͙̰̪͍̠̭̲͖̞̰̳͍̲̞̭̥̘͖̫̙̥͉̮̱̮́͋̔̇̅̎̽̾̑͌̏̈́̈̃̈̄̊̎͒̒͂̂̇̏̀͋̉̔̾̓̃̈́́͆̀̓̊̋̈́͐͂͆́͐͂̈́̕̚̚͘͜͜͜͝͝͝͝ͅz̸̛̛̻̯̱̱̺̫͍͔̔̋́͑̉̔̀́̈̈́͗̐̈̀̐͑̋̏͂̈́͐͑̆͐̂̈͊̑̈́̽̈́́̀́̿̇͋́͐̊̏̒́́͂̈́̋́̕̚̕̕̕͝͝͠͝͝ ̴̧̨̡̧̡̟͎̭͔͖̮̺͖͙̼̦̻͍͚̭̠̟̯͔͍̖̝͎̠̭̱̦̱̻̤͚̺̲̞̩͍̭̼̲̻͎͙̝͔̺̖̘̫̰͚̮͉̯̬̩͖̭̞̹̻̻͍͖͉̥̮͖̫͙̦͉̘͙̞̲̼̯̩̞̯̗̗̬̫͍̇́̀̍̎̾̏͋̅̀͌̓̋̾͊̀̃͆̄͋͌̇͆̈́̊̊̆̿́̊͑̏̄̐̎̄̈́̔̐̀̽̃̄̓͊͗̋̇̓̽̐͐͒͒̔̈͌̀͂̆̊̍̉́͑̕̚̕̕͜͜͜͜͝͝ͅͅͅt̷̢̨̡̡̧̛̛̙̱̦̗̹̫̥̭͉̩͙̯̖̖̟̥͕̥̳̥̹̩̳̮̟̝͔̬͇̠̰̠̮̳̖͍̮̬̝̜͇̠̠̱̗̖̩͕̲̤̬̱̲̹̗̳̞̣͕̼̳̯̰̮͆̋́̅̄͂͋̐̐̑̄̿̀̑̿̿̎̆̉̔̅̉̾̈́͛̔̐̈́͐̌͗́͗̀̀̊̄̉̽̉͛̅̽̃̉́̅͒̇̃́̍̈́̄͋̕̚͘̚̚̚̚͜͜͜͜͠͠͝͝͠͝͠͝ͅé̵̡̡̢̡̨̛̤͉̦͈̟̱̜̯͈͎͉͎̹͖͎̘̮͓̻͓̱̫̩̘̥͙̺̖̟̿̑̀̔̑̈́͛̓͌̊̔̔̑̒͗̈͆̂̉̅̏̽̇̚̕͝ͅͅs̷̡̛̙͓̲̱͉̥̩̠͋̓̽͑̃̉͌̐̐͗̀̃̓̌̇̿̓̆͂͗̇̍͘̚̕ţ̴̨̨̢̙̠̝̼̭̗̞͉̲͇̜̙͔̩̻̠̟̯̪̫̯̜̞͚̼͚͚̫̬̪̰͍͎̭̻̳̘̩͇͍̖͕̣̱̤̥͖̫̊̏̄́͑̀i̴̧̦͙͙̱̹̰̲̭͔̤͍̦̼̰̻̱̩̩͍̘̪̘̥͉͓̟̰̳̱̖̍͆̋͆͊̉̉̀̿̑́̇̇͆̎̒͘͘͜͝͝n̶̛̛̬̤̱̼̯̰͖̮̲̦̻͍̯͖̈̒̃͆̌̔̍̿̐̆͒͂͊̂͒̽̈̑̔̊́̃̂̋͒̈́̃͂͆̀̓̂͐̃̔̅̀̊̆̽̆͑̄̅͋̑͋̓̈́̌̏͐̉͌͐͋̓̓̑͒͌́̿̃̋̔͊̿̐̓̔̍̋͛̾̅̄̃̄̈̚͘͘̚̚̕͝͝͠͠͝͝ģ̸̛̮͎͙̱̘̺̝̹̾̓̉͗͗͛͌͆̽̇̃̌̓͊͂̇͗̈́͗̄̎̐̆́̋̊̃́̍̃̏̈́̔̌̈́͐̿̾̋̍̌̒̑̄̈́̊̑̋͗̽̈́̍̇̽̕̕̚̚͘̚͠
REALLY test your code
Get to feel super cool using a weird testing method
🎉
Increased confidence
Can be very slow
🤮
Immature in JS
Only applicable to some things
But... I want to know my tests are good
Tests your tests!
Easy with libraries like Stryker
🎉
