macos-test-diagnoser

name	macos-test-diagnoser
description	macOS Xcode and SwiftPM tests: run focused scopes and diagnose build, assertion, crash, async-flake, fixture, entitlement, and host-app failures; separate regressions from setup issues.

macOS Test Diagnoser

Before invoking Apple-only binaries, confirm the execution context is macOS. From Windows or Linux, run those steps in a Mac SSH project or through an already configured remote transport; do not retry missing Apple binaries locally.

Quick Start

Use this skill to run the smallest meaningful test scope first, classify failures precisely, and avoid treating every test failure like a product bug.

Workflow

1. Detect the test harness.

   • Use xcodebuild test for Xcode-based projects.
   • Use swift test for SwiftPM packages.

2. Narrow the scope.

   • If the user gave a target, product, or test filter, use it.
   • If not, prefer the smallest likely failing target before a full suite.

3. Classify the result.

   • Build failure
   • Assertion failure
   • Crash or signal
   • Async timing or flake
   • Environment or fixture setup issue
   • Missing entitlement or host app issue

4. Rerun intelligently.

   • Use focused reruns when a specific case fails.
   • Avoid burning time on full-suite reruns without new information.

5. Summarize clearly.

   • What command ran
   • Which tests failed
   • What kind of failure it was
   • The best next proof step or fix path

Result Bundle Inspection

When console output alone is not enough, read the .xcresult bundle instead of rerunning:

• Pass -resultBundlePath ./Tests.xcresult to xcodebuild test so evidence lands at a known path.
• Run summary: xcrun xcresulttool get test-results summary --path Tests.xcresult
• Per-test outcomes: xcrun xcresulttool get test-results tests --path Tests.xcresult
• One failure in depth: xcrun xcresulttool get test-results test-details --test-id <id> --path Tests.xcresult
• Attachments such as screenshots and logs: xcrun xcresulttool export attachments --path Tests.xcresult --output-path ./attachments
• Older bundles or full object graph: xcrun xcresulttool get --legacy --format json --path Tests.xcresult (drop --legacy on pre-Xcode 16 toolchains).

swift test produces no .xcresult; use console output, --filter reruns, and --xunit-output when a machine-readable report is needed.

Guardrails

• Distinguish compilation failures from test execution failures.
• Call out when a test appears to assume iOS-only or simulator-only behavior.
• Mark likely flakes as such instead of overstating confidence.

Output Expectations

Provide:

• the command used
• the smallest failing scope
• the .xcresult path when one was produced
• the top failure category
• a concise explanation of the likely cause
• the next rerun or fix step