Swift Testing

This walks you through Swift Testing, Apple's macro-based replacement for XCTest. It covers the #expect/#require distinction (most checks should use #expect, not #require), async testing without the Task wrapper nonsense, and parameterized tests with zip to avoid accidental Cartesian products. The migration table from XCTest assertions is handy if you're converting existing tests. Biggest gotcha: tests run in parallel by default, so you'll need .serialized for anything touching shared state. Good reference if you're tired of XCTest's verbosity or finally moving a real codebase to the new framework.

skills.sh installs: 209
GitHub stars: 233
last updated: Aug 21, 2026

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Install

$ npx -y skills add johnrogers/claude-swift-engineering --skill swift-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

Swift Testing Framework

Modern testing with Swift Testing framework. No XCTest.

Overview

Swift Testing replaces XCTest with a modern macro-based approach that's more concise, has better async support, and runs tests in parallel by default. The core principle: if you learned XCTest, unlearn it—Swift Testing works differently.

References

Core Concepts

Assertions

Macro	Use Case
`#expect(expression)`	Soft check — continues on failure. Use for most assertions.
`#require(expression)`	Hard check — stops test on failure. Use for preconditions only.

Optional Unwrapping

let user = try #require(await fetchUser(id: "123"))
#expect(user.id == "123")

Test Structure

import Testing
@testable import YourModule

SKILL.md on GitHub

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Details

Repository: github.com/johnrogers/claude-swift-engineering
Categories: Testing & QA, Documentation, Mobile Development
First seen: Jun 3, 2026

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