WWDC 2017

Table of Contents

Engineering for Testability - Friday
Testable App Code
Scalable Test Code
- Balance Between UI & Unit Tests
- Code to help UI Tests Scale
Treat your test code with the same amount of care as your app code
- Quality of Test Code

Engineering for Testability - Friday

Session video and resources: https://developer.apple.com/videos/play/wwdc2017/414/ This is the best session !

Testable App Code

Structure of a Unit Test

Prepare input
Run the code being tested
Verify output

Characteristics of Testable Code

Control over inputs
Visibility into outputs

Protocols and Parameterization

Reduce references to shared instances
Accept parameterized input
Introduce a protocol
Create a testing implementation (mocks)

Seperating Logic and Effects

Extract algorithms into separate types, away from the code using side effects
Functional style with value types. Input -> Outputs
Thin layer on top to execute effects

Scalable Test Code

Balance Between UI & Unit Tests

Testing pyramid -> UI, Integration Tests, Unit Tests

Code to help UI Tests Scale

Abstracting UI element queries

Store part of queries in a variable
Wrap complex queries in utility methods
Reduces noise and clutter in UI tests

Creating objects and utility functions

Encapsulate common testing workflows
Cross-platform code sharing
Improves maintainability

Utilizing Keyboard Shortcuts

Avoid working through menu bar for macOS
Make code more compact

Treat your test code with the same amount of care as your app code

Important to consider even though it isn't shipping
Test code should support the evolution of your app
Coding principles should apply to tests as well
Code reviews for test code, not code reviews with test code

Quality of Test Code