swift-testing-pro Skill for Claude: What It Does and How to Install It

Makes Claude write and review Swift Testing code with current APIs, and avoid XCTest habits that models carry over from training data.

Installs: 10.3K; on skills.sh
Stars: 472; on GitHub
Files: 9; besides SKILL.md
Updated: May 2026; last repo commit

This skill is Paul Hudson's Swift Testing guide for AI coding assistants. Claude checks your tests against five reference files: core rules, test structure and assertions, async tests, new features such as exit tests and attachments, and XCTest migration.

For a review it reports problems by file, with the line, the rule broken and a before-and-after fix. It then ends with a prioritized summary. SKILL.md says to report only genuine problems. If you ask it to write or improve tests, it makes the changes directly.

Good for

iOS and Mac developers moving from XCTest to Swift Testing
Teams reviewing test suites for modern Swift Testing style
Anyone adding parameterized, async or exit tests

Install swift-testing-pro

Claude Code

Copy this prompt.

Install the swift-testing-pro skill in Claude Code. Run this command:

/plugin marketplace add twostraws/Swift-Testing-Agent-Skill
/plugin install swift-testing-pro@swift-testing-agent-skill

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Pick one route. The plugin route installs swift-testing-pro from the repo's marketplace, which lists one plugin. The README documents the skills command for Codex, Gemini, Cursor and others. The skill bundles no scripts. It targets Swift 6.2 or later.

From the project README. Source.

What's in the skill

When it loads

Writes, reviews, and improves Swift Testing code using modern APIs and best practices. Use when reading, writing, or reviewing projects that use Swift Testing.

Sections in SKILL.md

Core Instructions
Output Format
UserTests.swift
Summary
References

Key facts

Author: Paul Hudson
License: MIT (SKILL.md frontmatter and README)
Installs on skills.sh: 10,315 (Nov 2, 2026)
GitHub stars: 472 for the whole twostraws/swift-testing-agent-skill repo (Nov 2, 2026)
Last repo commit: May 17, 2026
What it includes: 12 files in the folder: SKILL.md, 5 reference files, 2 icon files, agents/openai.yaml, a plugin.json and a plugin copy of SKILL.md with a references link. No scripts
Needs: Swift 6.2 or later. The skill targets Swift 6.2+ and says UI tests must stay on XCTest
Works in: Claude Code, Codex, Cursor and Gemini, per the README

What it includes

Structs over classes, init over setUp, parallel runs, tags
First review step. Covers parameterized tests, withKnownIssue and the point that UI tests still need XCTest (references/core-rules.md).
Try: “Review the tests in this project with swift-testing-pro.”
Read · Core rules
Structure, #expect vs #require, Issue.record, #expect(throws:)
Checks test hygiene, hidden dependencies, dependency injection and how results are verified.
Read · Writing better tests
Serialized tests, confirmation(), time limits, actor isolation
Also covers testing pre-concurrency code and mocking networking.
Read · Async tests
Raw identifiers, exit tests, attachments, test scoping traits
Checks use of newer APIs, including range-based confirmations and the updated #expect(throws:) return value.
Read · New features
Conversion steps and assertion mappings
Used when you ask to move XCTest code to Swift Testing, including floating-point tolerance with Swift Numerics.
Write · Migrating from XCTest
By file: line, rule, before and after, then a ranked summary
Files with no issues are skipped. Each finding names the rule it breaks.
Read · Review output format
Makes the edits directly instead of a findings report
Used when you ask for new or improved tests.
Write · Write or improve mode

From the official docs

Permissions

Low risk

Claude can edit your test files directly when you ask it to write or improve tests. Review the diff before you commit.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It edits your test files
SKILL.md says that when you ask it to write or improve tests it makes the changes directly instead of returning a findings report. Review the diff before you commit. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	No read-only mode. Use version control.
Sign-in and keys	SKILL.md mentions no account or key.
Scopes	In write or improve mode, Claude edits your test files directly In review mode, Claude reports findings by file and line

Questions

What does the swift-testing-pro skill do?

It makes Claude write and review tests with Apple's Swift Testing framework. It targets mistakes models make, such as reskinning XCTest or missing newer features.

How do I install swift-testing-pro?

Use the install box at the top of this page. The README gives a plugin route for Claude Code and a skills command for Codex, Gemini, Cursor and others.

How do I trigger it?

The README says to type /swift-testing-pro in Claude Code or $swift-testing-pro in Codex, optionally followed by instructions. You can also ask in plain words to use the Swift Testing Pro skill.

Does it cover UI tests?

No. SKILL.md says Swift Testing does not support UI tests, so XCTest must be used there.

Which Swift version does it assume?

Swift 6.2 or later with modern Swift concurrency. SKILL.md says to treat the toolchain you have installed as authoritative, because Apple's documentation for new APIs may be stale.

Is it safe?

It bundles no scripts. In write mode Claude edits your test files, so review the diff. The skill itself tells Claude to report only genuine problems and not invent issues.

Information

updated Nov 2, 2026

Repository: twostraws/swift-testing-agent-skill
Folder: swift-testing-pro

twostraws/swift-testing-agent-skill skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 4

swift-testing-pro SKILL.md · github.com
Swift Testing Agent Skill README · github.com
marketplace.json · github.com
core-rules.md · github.com