Javi Lorbada JaviLorbada

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.

1. Migration & Tooling Baseline

1. Using ZSH in your Terminal

MacOS Catalina has changed the default terminal from Bash to ZSH. As a result, we'll be adding configs to ~/.zshrc instead of ~/.bash_profile like we used in the past. You can manually change from Bash to ZSH anytime by running the following command:

chsh -s /bin/zsh

2. Install Homebrew

First, we need to install Homebrew. Homebrew allows us to install and compile software packages easily from source. Homebrew comes with a very simple install script. When it asks you to install XCode CommandLine Tools, say yes. Open Terminal and run the following command:

Threads

Foundation offers a Thread class, internally based on pthread, that can be used to create new threads and execute closures.

// Detaches a new thread and uses the specified selector as the thread entry point.
Thread.detachNewThreadSelector(selector: Selector>, toTarget: Any, with: Any)

// Subclass
class MyThread: Thread {

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

Hide iOS Simulator when running Unit Tests.

Based on this work, that @Dan2552 pointed out.

Instructions:

Clone this gist (git clone https://gist.github.com/6201428.git hide_ios_simulator)
Xcode -> Preferences -> Behavior -> Testing -> Generates output
Run script -> Choose script -> Select hide_simulator

	import UIKit
	import WebKit

	final class ReCAPTCHAViewController: UIViewController {
	private var webView: WKWebView!
	private let viewModel: ReCAPTCHAViewModel

	init(viewModel: ReCAPTCHAViewModel) {
	self.viewModel = viewModel

	#!/bin/bash
	# Place this file in `.git/hooks/`

	if which swiftlint >/dev/null; then
	swiftlint autocorrect
	else
	echo "warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint"
	fi

	git diff --diff-filter=d --staged --name-only \| grep -e '\(.*\).swift$' \| while read line; do

	#!/bin/bash

	# To update or install in a new repository, run the following command
	# N=.git/hooks/prepare-commit-msg ; curl -L https://goo.gl/5Mmuoi -o $N --create-dirs; chmod 744 $N

	# Assuming all branches are created as `WWW-nnn-Human-readable-suffixes`
	# this commit-msg hook will prepend all commit messages with the ticket
	# name/number, for example:
	# Branch: ADV-007-License-to-kill
	# Message: Bad guy has been identified.

	typedef enum _UIBackgroundStyle {
	UIBackgroundStyleDefault,
	UIBackgroundStyleTransparent,
	UIBackgroundStyleLightBlur,
	UIBackgroundStyleDarkBlur,
	UIBackgroundStyleDarkTranslucent
	} UIBackgroundStyle;

	@interface UIApplication (UIBackgroundStyle)
	-(void)_setBackgroundStyle:(UIBackgroundStyle)style;

	// Just before switching jobs:
	// Add one of these.
	// Preferably into the same commit where you do a large merge.
	//
	// This started as a tweet with a joke of "C++ pro-tip: #define private public",
	// and then it quickly escalated into more and more evil suggestions.
	// I've tried to capture interesting suggestions here.
	//
	// Contributors: @r2d2rigo, @joeldevahl, @msinilo, @_Humus_,
	// @YuriyODonnell, @rygorous, @cmuratori, @mike_acton, @grumpygiant,