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.

---

1. Migration & Tooling Baseline

LeoNatan

/**
 The MIT License (MIT)
 
 Copyright (c) 2024 Léo Natan
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is

ivmirx

Disclaimer: many of those are extremely important but I believe that social media isn't fit to discuss them

## Politics ##
alt-right
bipartisan
Brexit
Capitol
CCP
China
CIA

stephancasas

//
//  CGWindowDictionary.swift
//
//  Created by Stephan Casas on 11/2/23.
//

import Foundation
import CoreGraphics
import AppKit

stephancasas

//
//  CGCoordinateSpaces.swift
//
//  Created by Stephan Casas on 11/7/23.
//

import Foundation;

// MARK: - CGPoint

mackuba

[
  {
    "id": "wwdc2010-118",
    "title": "Mastering Core Data",
    "description": "Core Data contains a vast set of advanced features to help you better manage your data and evolve your application over time. Master the techniques for working with data in your application, from being more efficient to doing more in the database and changing how you store your data over time. Take your Core Data knowledge to the next level.",
    "links": [
      [
        "HD",
        "https://developer.apple.com/devcenter/download.action?path=/videos/wwdc_2010__hd/session_118__mastering_core_data.mov"
      ],

saagarjha

// Usage should be fairly self-explanatory, just paste this in a header and use
// CRASH_WITH_MESSAGE("foobar") in your function.
// Example backtrace:
// Thread 0 Crashed::  Dispatch queue: com.apple.main-thread
// 0   ???                           	       0x1022d8000 CRASHING IN test.c:20 (foobar) + 0
// 1   a.out                         	       0x1022d7f60 main + 24
// 2   dyld                          	       0x195f07e50 start + 2544

#define STRINGIFY(a) #a
#define CRASH_FUNCTION_NAME(file, line, message) "CRASHING IN " file ":" STRINGIFY(line) " (" message ")"

saagarjha

// Example usage:
// Swizzler<NSString *, NSDateFormatter *, NSDate *> NSDateFormatter_stringFromDate_ {
//     NSDateFormatter.class, @selector(stringFromDate:), [&](auto self, auto date) {
//         if ([NSCalendar.currentCalendar components:NSCalendarUnitWeekday fromDate:date].weekday == 4) {
//             return @"It Is Wednesday My Dudes";
//         } else {
//             return NSDateFormatter_stringFromDate_(self, date);
//         }
//     }
// };

pilky

class SourceListTableCellView: NSTableCellView {
    override var draggingImageComponents: [NSDraggingImageComponent] {
        let components = super.draggingImageComponents
        guard
            self.backgroundStyle == .emphasized, //emphasized = selected
            let textField = self.textField,
            let newStyle = textField.attributedStringValue.mutableCopy() as? NSMutableAttributedString,
            let labelIndex = components.firstIndex(where: { $0.key == .label })
        else {
            return components

Catfish-Man

// Compile with clang -framework Foundation sethack.m

#import <Foundation/Foundation.h>
#import <objc/runtime.h>

/*
 CFHashBytes from http://www.opensource.apple.com/source/CF/CF-1153.18/CFUtilities.c
 */
#define ELF_STEP(B) T1 = (H << 4) + B; T2 = T1 & 0xF0000000; if (T2) T1 ^= (T2 >> 24); T1 &= (~T2); H = T1;