Testing

You MUST use this skill for ANY testing-related question, including writing tests, debugging test failures, making tests faster, or choosing between testing approaches.

Bundled tools on Claude Code: if command -v <tool> finds nothing (hooks off or --bare), use <plugin-root>/tools/<tool> in place of the bare name; <plugin-root> is two levels above this skill's Base directory for this skill: path.

Can't launch Axiom agents? Where this router sends you to an agent, follow its procedure inline. Over MCP, axiom_get_agent returns it; elsewhere, read its file below, which needs only file search and read.

Available here: skills/test-failure-analyzer.md, skills/testing-auditor.md.

For any other agent, over MCP axiom_get_agent returns it too; run its xclog, xcsym and xcprof steps with the axiom_xclog_*, axiom_xcsym_* and axiom_xcprof_* tools. Elsewhere, search Axiom's skills for skills/<agent>.md; if there is none, do that work yourself with this suite's skills, using any Axiom tool on your PATH.

Quick Reference

Symptom / Task	Reference
Writing unit tests, Swift Testing (@Test, #expect)	See skills/swift-testing.md
Making tests run without simulator	See skills/swift-testing.md
Parameterized tests, tags, traits	See skills/swift-testing.md
Migrating from XCTest to Swift Testing	See skills/swift-testing.md
Warning-severity issues / cancelling a test — Issue.record(severity:), Test.cancel (OS27)	See skills/swift-testing.md
Testing async/await functions	See skills/testing-async.md
confirmation for callbacks	See skills/testing-async.md
@MainActor tests, parallel execution	See skills/testing-async.md
Writing UI tests, XCUITest	See skills/ui-testing.md
Driving VoiceOver from a UI test, asserting spoken output (OS27)	See skills/ui-testing.md Pattern 7
Testing App Intents through the system, AppIntentsTesting (OS27)	See skills/ui-testing.md Pattern 8, then axiom-integration (skills/app-intents-ref.md)
Condition-based waiting patterns	See skills/ui-testing.md
Recording UI Automation (Xcode 26)	See skills/ui-testing.md
Network conditioning, multi-factor testing	See skills/ui-testing.md
Testing resizable apps: dimension matrix, RTL/pseudoloc launch args, live-resize passes	See skills/ui-testing.md
Test Face ID/Touch ID, orientation, or simulator state from CI — devicectl	See skills/ui-testing.md
XCUIElement queries, waiting strategies	See skills/xctest-automation.md
Accessibility identifiers, test plans	See skills/xctest-automation.md
CI/CD test execution	See skills/xctest-automation.md
Record/Replay/Review workflow (Xcode 26)	See skills/ui-recording.md
Test plan multi-configuration replay	See skills/ui-recording.md
Enhancing recorded tests for stability	See skills/ui-recording.md
Testing a generative AI feature — output isn't deterministic, so #expect(result == expected) doesn't hold (OS27)	See axiom-ai (skills/foundation-models-evaluations.md) for the discipline, then axiom-ai (skills/foundation-models-evaluations-ref.md) for the API

Decision Tree

digraph testing {
    start [label="Testing task" shape=ellipse];
    what [label="What kind of test?" shape=diamond];

    start -> what;
    what -> "skills/swift-testing.md" [label="unit tests,\nSwift Testing,\nfast tests"];
    what -> "skills/testing-async.md" [label="testing async code,\ncallbacks,\nconfirmation"];
    what -> "skills/ui-testing.md" [label="UI tests,\nflaky tests,\nrecording"];
    what -> "skills/xctest-automation.md" [label="XCUITest patterns,\nelement queries"];
    what -> "skills/ui-recording.md" [label="Xcode 26\nRecord/Replay/Review"];
    what -> "axiom-ai (skills/foundation-models-evaluations.md)" [label="generative AI feature\n(nondeterministic output)"];
}

1. Writing unit tests / Swift Testing? → skills/swift-testing.md
2. Testing async/await code? → skills/testing-async.md
3. Writing UI tests / XCUITest / flaky tests? → skills/ui-testing.md
4. XCUIElement queries, waiting, test plans, CI? → skills/xctest-automation.md
5. Record UI interactions (Xcode 26)? → skills/ui-recording.md
6. Flaky tests / race conditions (Swift Testing)? → test-failure-analyzer (Agent)
7. Tests crash / environment wrong? → See axiom-build (skills/xcode-debugging.md)
8. Run tests from CLI / parse results? → test-runner (Agent)
9. Fix failing tests automatically? → test-debugger (Agent)
10. Want test quality audit? → testing-auditor (Agent) or /axiom:audit testing
11. Automate without XCUITest / AXe CLI? → simulator-tester (Agent) + See axiom-xcode-mcp (skills/axe-ref.md)
12. Testing a Foundation Models / generative feature? → See axiom-ai (skills/foundation-models-evaluations.md) for the discipline (dataset design, guardrails vs optimization target, judge calibration), then axiom-ai (skills/foundation-models-evaluations-ref.md) for the API. The Evaluations framework (OS27) runs inside Swift Testing via the .evaluates trait — it doesn't replace it. A model isn't a pure function, so you score outputs against a dataset and gate on an aggregate metric instead of asserting on one exact string.

Swift Testing vs XCTest Quick Guide

Need	Use
Unit tests (logic, models)	Swift Testing
UI tests (tap, swipe, assert screens)	XCUITest (XCTest)
App Intents run through the system (AppIntentsTesting)	UI Testing Bundle with XCTest. Swift Testing works there only with an undocumented build-setting override
Tests without simulator	Package/Framework (either framework)
Parameterized tests	Swift Testing
Performance measurements	XCTest (XCTMetric)
Objective-C tests	XCTest

Critical Patterns

Swift Testing (skills/swift-testing.md):

• @Test/@Suite macros, #expect/#require assertions
• Parameterized testing for eliminating repetitive tests
• Fast tests architecture: Package extraction, Host Application: None
• Reliable async testing with withMainSerialExecutor and TestClock
• Migration guide from XCTest (comparison table)
• XCTestCase + Swift 6.2 MainActor compatibility fix

Async Testing (skills/testing-async.md):

• confirmation for single/multiple callbacks
• expectedCount: 0 to verify something never happens
• @MainActor test isolation
• Timeout control with .timeLimit
• Parallel execution gotchas and .serialized

UI Testing (skills/ui-testing.md):

• Condition-based waiting (replaces sleep())
• Recording UI Automation (Xcode 26)
• Network conditioning for 3G/LTE testing
• Multi-factor testing (device size + network speed)
• Crash debugging from UI test failures

XCUITest Automation (skills/xctest-automation.md):

• Element identification with accessibilityIdentifier
• Waiting strategies (appear, disappear, hittable)
• Test plans for multi-configuration testing
• CI/CD integration with parallel execution

UI Recording (skills/ui-recording.md):

• Xcode 26 Record/Replay/Review workflow
• Enhancing recorded code for stability
• Query selection guidelines
• Test plan configuration for multi-language replay