Test Loop

iOS Test Pilot: Build-Test-Fix Loop

Build an iOS app, launch it on the simulator, inspect and test the UI, fix issues, and repeat until it works.

Arguments

First argument: build command (required). Remaining text: test description (optional).

If no test description, do a general inspection: build, launch, screenshot, read the accessibility tree, report what you see.

Protocol

1. Prepare

If the build command is a custom script, read it first to understand what it handles (compile only? install/launch too?). This determines which later steps you can skip.

2. Build

Run the build command. On failure, don't dump the full log — scan for lines containing error: and the few lines around them. Read the referenced source file, fix the issue, and rebuild. Common patterns:

• Type errors / missing imports — straightforward code fix
• Signing errors — set CODE_SIGNING_ALLOWED=NO in the build command for simulator builds
• Missing dependencies — check if a Swift Package needs resolving (xcodebuild -resolvePackageDependencies)

3. Find the .app

Skip if the build script already installed and launched the app.

Locate the built .app bundle:

1. Check build output for the path — xcodebuild prints it, and scripts often echo it
2. If not found, search DerivedData:

   find ~/Library/Developer/Xcode/DerivedData -name "*.app" -path "*/Debug-iphonesimulator/*" -newer /tmp/.build_start_marker -maxdepth 6 2>/dev/null
   

   (Create /tmp/.build_start_marker with touch before the first build to filter stale bundles.)
3. Fallback — search the working directory: find . build/ output/ -name "*.app" -maxdepth 4 2>/dev/null

If multiple results, pick the newest by modification time.

4. Boot Simulator and Launch

Skip if the build script already handled this.

xcrun simctl boot "iPhone 16" 2>/dev/null || true
open -a Simulator

Extract the bundle ID from the app:

/usr/libexec/PlistBuddy -c "Print :CFBundleIdentifier" /path/to/Built.app/Info.plist

Install with mcp__iosef__install_app, then launch with mcp__iosef__launch_app (set terminate_running: true to ensure a clean start).

Wait for the app to render. After launch, pause 2-3 seconds before inspecting — SwiftUI apps often show a blank frame initially while the view hierarchy loads. If the first screenshot is blank or shows only a launch screen, wait another 2 seconds and retry once before treating it as a bug.

5. Inspect and Test

Take a screenshot (mcp__iosef__view) and read the accessibility tree (mcp__iosef__describe).

If there's a test description: plan the interaction sequence, then execute step by step using iosef tools — tap, type, swipe, find, wait, exists. Screenshot after each significant action so you can trace what happened if something goes wrong.

If no test description: do a general walkthrough — screenshot the initial state, tap the main interactive elements, verify the app responds sensibly, and report what you find.

Handling permission dialogs: iOS may show system alerts (location, notifications, camera, etc.) that block your app's UI. If mcp__iosef__describe shows a system alert, either tap "Allow" / "Don't Allow" as appropriate for the test, or dismiss it. Don't mistake a permission dialog for a bug in the app.

6. On Failure

1. Diagnose first. Compare what you expected vs. what you see. Check mcp__iosef__log_show for crash logs or assertion failures — filter by the app's bundle ID or process name to cut through noise.
2. Read the relevant source, then fix the code. If elements are hard to target, add .accessibilityIdentifier("descriptive-id") to key views — this is a legitimate fix, not a refactor.
3. Rebuild and retest (go back to step 2).

Iteration limits: You have up to 5 build-test-fix cycles. If you're not making progress by iteration 3, step back and reconsider — are you fixing symptoms instead of the root cause? On iteration 5, if the issue persists, stop and report to the user: what you've tried, what the current state is, and your best theory on what's wrong.

7. On Success

Take a final screenshot as evidence. Report:

• The final state of the app (screenshot)
• A summary of any fixes you made (files changed, what was wrong, what you did)
• If no fixes were needed, just confirm the app works as expected

Rules

• Verify after every fix — rebuild and retest, never assume a fix worked.
• Minimum changes only — fix the issue, don't refactor surrounding code.
• Read before writing — always read a file before modifying it.
• Don't modify the build system unless the build error specifically requires it.
• Screenshot after every significant state change — screenshots are your evidence trail. If something goes wrong later, you can trace back through them to understand what happened.