steipete

The Ultimate Swift Testing Playbook (2024 WWDC Edition, expanded with Apple docs from June 2025)

Updated with info from https://developer.apple.com/documentation/testing fetched via Firecrawl on June 7, 2025.

See also my blog: See also my blog post: https://steipete.me/posts/2025/migrating-700-tests-to-swift-testing

A hands-on, comprehensive guide for migrating from XCTest to Swift Testing and mastering the new framework. This playbook integrates the latest patterns and best practices from WWDC 2024 and official Apple documentation to make your tests more powerful, expressive, and maintainable.

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1. Migration & Tooling Baseline

uvolchyk

import SwiftUI

struct HarmonicButton: View {
  var body: some View {
    Button(
      action: {},
      label: {}
    )
    .frame(width: 240.0, height: 70.0)
    .buttonStyle(HarmonicStyle())

morajabi

import AppKit
import Charts
import CoreVideo
import SwiftUI

struct FPSMeasurement: Identifiable, Equatable {
    let id: Int
    let fps: Int
    
    static func == (lhs: FPSMeasurement, rhs: FPSMeasurement) -> Bool {

usagimaru

Use _NS_4445425547 or NS🐞 for enables debuggging panel. When enabled it, a ladybug 🐞 menu appears in the app menu bar.

“4445425547” means DEBUG in Unicode table.

0x44=D
0x45=E
0x42=B
0x55=U
0x47=G

stephancasas

//
//  NSApplication+openSettings.swift
//
//  Created by Stephan Casas on 12/3/23.
//

import SwiftUI;

fileprivate let kAppMenuInternalIdentifier  = "app"
fileprivate let kSettingsLocalizedStringKey = "Settings\\U2026";

Sherlouk

//
// DebugDevice.swift
//
// Copyright 2022 • Sidetrack Tech Limited
//

import Foundation

// This must be called on the main-thread.
var isDebugProfileInstalled: Bool {

taskcruncher

//How to use BaseState struct to share state between views in TCA architecture. 
// https://forums.swift.org/t/best-practice-for-sharing-data-between-many-features/37696/4

//This is a proof-of-concept only; it simply is an attempt to model how to get and set global shared state among different views in a TCA-style app.
import SwiftUI
import ComposableArchitecture

@dynamicMemberLookup

struct TCABaseState<State: Equatable>: Equatable{

jordansinger

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack(spacing: 0) {
            Color.green
            Color.green
            Color.green
            Color.yellow
            Color.orange

steipete

extension Color {
    /// Return a random color
    static var random: Color {
        return Color(
            red: .random(in: 0...1),
            green: .random(in: 0...1),
            blue: .random(in: 0...1)
        )
    }
}

ytyubox

extension Result {
    func tryMap<T>(_ transform:(Success) throws -> T)  -> Result<T, Swift.Error> {
        switch self {
            case let .success(success):
                do {
                    return .success(try transform(success))
                } catch {
                    return .failure(error)
                }
            case let .failure(failure):