swift-testing-agent-skill

Swift Testing Agent Skill

Expert guidance for any AI coding tool that supports the Agent Skills open format - modern Swift Testing APIs, XCTest migration, parameterized tests, traits/tags, async testing, and parallel execution patterns.

This repository distills practical Swift Testing best practices into actionable, concise references for agents and code review workflows.

Who this is for

• Teams adopting Swift Testing who want quick, correct defaults
• Developers migrating existing XCTest suites incrementally
• Anyone debugging flaky tests, parallel test behavior, or async test reliability

See also my other skills:

• SwiftUI Expert
• Swift Concurrency Expert
• Core Data Expert

How to Use This Skill

Option A: Using skills.sh (recommended)

Install this skill with a single command:

npx skills add https://github.com/avdlee/swift-testing-agent-skill --skill swift-testing-expert

For more information, visit the skills.sh platform page.

Then use the skill in your AI agent, for example:

Use the swift testing skill and review this test target for migration opportunities and flaky parallel behavior.

Option B: Claude Code Plugin

Personal Usage

To install this Skill for your personal use in Claude Code:

1. Add the marketplace:

/plugin marketplace add AvdLee/Swift-Testing-Agent-Skill

2. Install the Skill:

/plugin install swift-testing-expert@swift-testing-agent-skill

Project Configuration

To automatically provide this Skill to everyone working in a repository, configure the repository's .claude/settings.json:

{
  "enabledPlugins": {
    "swift-testing-expert@swift-testing-agent-skill": true
  },
  "extraKnownMarketplaces": {
    "swift-testing-agent-skill": {
      "source": {
        "source": "github",
        "repo": "AvdLee/Swift-Testing-Agent-Skill"
      }
    }
  }
}

When team members open the project, Claude Code will prompt them to install the Skill.

Option C: Manual install

1. Clone this repository.
2. Install or symlink the swift-testing-expert/ folder following your tool's official skills installation docs (see links below).
3. Use your AI tool as usual and ask it to use the "swift-testing-expert" skill for Swift Testing tasks.

Where to Save Skills

Follow your tool's official documentation, here are a few popular ones:

• Codex: Where to save skills
• Claude: Using Skills
• Cursor: Enabling Skills

How to verify:

Your agent should reference the routing/playbook in swift-testing-expert/SKILL.md and jump into the relevant file in swift-testing-expert/references/.

What This Skill Offers

This skill gives your AI coding tool practical Swift Testing guidance. It can:

Guide Your Test Architecture Decisions

• Choose when to use suites, traits, tags, and display names
• Convert repetitive tests into parameterized tests with clean argument design
• Apply parallel-safe patterns and know when .serialized is a temporary compromise
• Set up tag-driven test plan filtering and report analysis workflows

Write Better Swift Tests

• Use #expect effectively with rich diagnostics
• Use #require for prerequisite flow and safer unwrapping
• Model thrown-error expectations clearly
• Improve output readability with test-specific descriptions

Migrate from XCTest Pragmatically

• Coexist Swift Testing and XCTest in one target during migration
• Map common XCTAssert* patterns to Swift Testing macros
• Keep XCTest where still required (XCUIApplication, XCTMetric, Objective-C tests)
• Convert duplicated XCTest methods into parameterized Swift Testing coverage

Improve Reliability and Performance

• Remove hidden inter-test dependencies surfaced by randomized, parallel execution
• Stabilize server-side tests with repository isolation and in-memory implementations
• Bridge callback APIs to async/await for deterministic tests
• Reduce CI noise with known-issue handling and actionable trait metadata

What Makes This Skill Different

Source-grounded: Built from SwiftLee's complete Swift Testing article set plus WWDC 2024 sessions "Meet Swift Testing" and "Go further with Swift Testing."

Non-Opinionated: Focuses on test correctness, readability, and maintainability without forcing a project architecture.

Modern-first: Prioritizes Swift Testing primitives, parallel defaults, and macro-based diagnostics over legacy assertion styles.