Use shared EmulatorRunner from android-tools for BootAndroidEmulator

[rmarinho]

Summary

Replaces the 454-line BootAndroidEmulator MSBuild task with a ~180-line thin wrapper that delegates boot logic to EmulatorRunner.BootEmulatorAsync() from Xamarin.Android.Tools.AndroidSdk (shared via the external/xamarin-android-tools submodule).

This is the consumer PR that @jonathanpeppers requested on android-tools#284:

"Is there a dotnet/android PR that tests this API? I think the task is <BootAndroidEmulator/> we could replace existing code and call this instead."

What Changed

BootAndroidEmulator.cs (454 → ~180 lines)

Removed:

• All process management (Process.Start, async output capture, CancelOutputRead/CancelErrorRead)
• All polling logic (WaitForEmulatorOnline, WaitForFullBoot, Thread.Sleep loops)
• All ADB interaction (IsOnlineAdbDevice, FindRunningEmulatorForAvd, GetRunningAvdName, GetShellProperty, RunShellCommand)
• MonoAndroidHelper.RunProcess calls (6 occurrences)

Added:

• Single ExecuteBoot() virtual method that creates AdbRunner + EmulatorRunner and calls BootEmulatorAsync()
• ParseExtraArguments() to split EmulatorExtraArguments string → string[]
• Error mapping: EmulatorBootResult.ErrorMessage → XA0143 (launch fail) / XA0145 (timeout/other)

Preserved:

• Same MSBuild task interface (all inputs/outputs unchanged)
• Same error codes (XA0143, XA0145) with same format strings
• ResolveAdbPath() / ResolveEmulatorPath() logic unchanged
• this.CreateTaskLogger() for MSBuild logging integration

BootAndroidEmulatorTests.cs (244 → ~250 lines, 9 → 10 tests)

New mock pattern: MockBootAndroidEmulator overrides ExecuteBoot() to return a canned EmulatorBootResult — much simpler than the previous approach of overriding 6 individual virtual methods.

Tests:

Test	Validates
AlreadyOnlineDevice_PassesThrough	Device already online → pass-through
AlreadyOnlinePhysicalDevice_PassesThrough	Physical device serial → pass-through
AvdAlreadyRunning_WaitsForFullBoot	AVD name → resolved serial
BootEmulator_AppearsAfterPolling	New emulator → assigned serial
LaunchFailure_ReturnsError	Launch fail → XA0143
BootTimeout_ReturnsError	Timeout → XA0145
MultipleEmulators_FindsCorrectAvd	Correct AVD resolution
ToolPaths_ResolvedFromAndroidSdkDirectory	Path defaults
ExtraArguments_PassedToOptions	✨ NEW — extra args parsed
UnknownError_MapsToXA0145	✨ NEW — fallback error code

Submodule Update

external/xamarin-android-tools updated from main (1a26c0c) → feature/emulator-runner (d8ee2d5)

API Used

From Xamarin.Android.Tools.AndroidSdk:

// EmulatorRunner — handles the full 3-phase boot flow
EmulatorRunner(string emulatorPath, logger: Action<TraceLevel, string>?)
EmulatorRunner.BootEmulatorAsync(string deviceOrAvdName, AdbRunner adbRunner, EmulatorBootOptions? options, CancellationToken)
  → Task<EmulatorBootResult>

// EmulatorBootResult — success/fail + serial + error message
record EmulatorBootResult { bool Success; string? Serial; string? ErrorMessage; }

// EmulatorBootOptions — timeout, extra args, cold boot
class EmulatorBootOptions { TimeSpan BootTimeout; IEnumerable<string>? AdditionalArgs; bool ColdBoot; }

// AdbRunner — device listing, shell properties (used internally by BootEmulatorAsync)
AdbRunner(string adbPath, logger: Action<TraceLevel, string>?)

Dependencies

⚠️ Draft PR — depends on dotnet/android-tools#284 merging first. After it merges:

1. Update submodule external/xamarin-android-tools to main
2. Take this PR out of draft

How dotnet/android Benefits

This establishes EmulatorRunner as the shared emulator management API. The same API is also consumed by:

• MAUI DevTools CLI (maui command) — for maui android emulator boot
• VS Code MAUI extension — for one-click emulator management

Having a single shared implementation means bug fixes and improvements benefit all consumers automatically.

cc @jonathanpeppers