Fix emulator boot and deploy flow for `dotnet run` by rmarinho · Pull Request #10969 · dotnet/android

rmarinho · 2026-03-18T18:18:54Z

Summary

Running dotnet run --project <app>.csproj with a stopped Android emulator fails to boot the emulator and deploy the app, producing adb: no devices/emulators found or adb: device '<avd>' not found errors.

This PR fixes the MSBuild target ordering so _EnsureDeviceBooted fires reliably during dotnet run deploy.

Fixes #10965

Problem & Fix

`_EnsureDeviceBooted` not firing during `DeployToDevice`

The .NET SDK's dotnet run invokes DeployToDevice via ProjectInstance.Build(["DeployToDevice"]) in-process. In this execution mode, BeforeTargets hooks are not reliably triggered — only DependsOnTargets chains are respected.

Fix: Add _EnsureDeviceBooted to DeployToDeviceDependsOnTargets in BuildOrder.targets, and to _AndroidComputeRunArgumentsDependsOn in Application.targets, ensuring the emulator boots via the dependency chain during both the main build and the deploy step.

Note: The BootAndroidEmulator.cs task itself was already updated to delegate to EmulatorRunner.BootEmulatorAsync in #10949 (now merged). This PR only addresses the MSBuild target wiring.

A related issue where Device was not passed as a global property to the deploy step was fixed in the .NET SDK (dotnet/sdk#53018).

Changes

Microsoft.Android.Sdk.Application.targets — Added _EnsureDeviceBooted to _AndroidComputeRunArgumentsDependsOn, simplified BeforeTargets to just _GetPrimaryCpuAbi (commercial builds), updated comments
Microsoft.Android.Sdk.BuildOrder.targets — Added _EnsureDeviceBooted to both DeployToDeviceDependsOnTargets variants (fast-deploy and non-fast-deploy)
BuildOrderTests.cs — Added DeployToDeviceDependsOn_ContainsEnsureDeviceBooted test

Testing

Unit test: DeployToDeviceDependsOn_ContainsEnsureDeviceBooted validates the target chain
Manual E2E: Verified on macOS with emulator 36.4.10 — emulator boots from cold, app deploys and launches with logcat streaming

jonathanpeppers

The problem on the description sounds like:

dotnet/sdk@07d7aa4

Which should be in main, if you have at least:

287f27d

Copilot

Pull request overview

Fixes dotnet run --project <app>.csproj deploy failures when the selected Android emulator is stopped by ensuring the emulator-boot target runs via DependsOnTargets, and improving emulator detection/boot polling in the BootAndroidEmulator MSBuild task.

Changes:

Add _EnsureDeviceBooted into DeployToDeviceDependsOnTargets and _AndroidComputeRunArgumentsDependsOn so it runs reliably during in-proc ProjectInstance.Build(["DeployToDevice"]).
Improve AVD name detection by preferring adb shell getprop ro.boot.qemu.avd_name, with fallback to adb emu avd name.
Handle macOS emulator launcher “fork then exit 0” behavior by continuing to poll adb devices on exit code 0.
Add a unit test asserting _EnsureDeviceBooted is included in DeployToDeviceDependsOnTargets.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Application.targets	Ensures `_EnsureDeviceBooted` participates in run-argument computation and clarifies execution rationale.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.BuildOrder.targets	Adds `_EnsureDeviceBooted` to deploy dependency chains (fast deploy + non-fast deploy).
src/Xamarin.Android.Build.Tasks/Tasks/BootAndroidEmulator.cs	Updates AVD name detection and improves macOS emulator process exit handling.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs	Adds coverage to validate deploy dependency chain includes `_EnsureDeviceBooted`.

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src/Xamarin.Android.Build.Tasks/Tasks/BootAndroidEmulator.cs

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs

Address multiple issues preventing 'dotnet run --project' from successfully booting an Android emulator and deploying the app. Fixes: #10965 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The dotnet/sdk fix (dotnet/sdk#53018) now properly passes the Device global property to DeployToDevice via InvalidateGlobalProperties. Remove the device.props write/read cache that was working around this. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The DeployToDeviceDependsOnTargets property expands to multiple log lines because it includes $(_MinimalSignAndroidPackageDependsOn). The test was only checking the first line, which never contained _EnsureDeviceBooted. Switch to MSBuild property functions (Contains/IndexOf) to validate directly in MSBuild, avoiding log parsing entirely. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Keep the readable log-parsing approach (fixed by joining all output lines for multi-line property matching) and add a separate MSBuild property function test as a safety net. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The IndexOf check for _EnsureDeviceBooted vs _DeployApk was scanning the entire build output, not just the property value. _DeployApk appears as a target reference earlier in the log, causing a false positive failure. Ordering is already validated reliably by DeployToDeviceDependsOn_MSBuildValidation which checks the property value directly via MSBuild functions. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jonathanpeppers

I'd rather this have a single end-to-end test that emulates the dotnet run pipeline:

dotnet build
dotnet build --no-restore -t:DeployToDevice
Assert DeployToDevice ran _EnsureDeviceBooted target
Assert the app is installed

You'll need to put this in tests/MSBuildDeviceIntegration, so you'll have access to a running emulator.

An emulator will already be booted, but that is OK. I think the bug here is that DeployToApk doesn't run _EnsureDeviceBooted.

Check there isn't an existing test that runs DeployToApk -- you could maybe update the existing test instead of adding new.

jonathanpeppers · 2026-03-23T22:05:14Z

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs

+		[Test]
+		public void DeployToDeviceDependsOn_ContainsEnsureDeviceBooted ()
+		{
+			// _EnsureDeviceBooted must be in DeployToDeviceDependsOnTargets so that it fires
+			// when the .NET SDK calls ProjectInstance.Build(["DeployToDevice"]) in-process,
+			// where BeforeTargets hooks are not reliably triggered.
+			var checkTargets = new Import (() => "CheckDeployOrder.targets") {
+				TextContent = () => """
+<Project>
+  <Target Name="_CheckDeployOrder">
+    <Message Text="DeployToDeviceDependsOnTargets=$(DeployToDeviceDependsOnTargets)" Importance="high" />
+  </Target>
+</Project>
+"""


This test is kind of pointless? It just checks a target named _EnsureDeviceBooted is in $(DeployToDeviceDependsOnTargets)?

That isn't really testing anything.

jonathanpeppers · 2026-03-23T22:06:03Z

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs

+			using var builder = CreateApkBuilder ();
+			Assert.IsTrue (builder.RunTarget (proj, "_CheckDeployOrder"),
+				"Build should have succeeded — _EnsureDeviceBooted must be in DeployToDeviceDependsOnTargets before _DeployApk.");


Same with this test, it's not really testing anything. It just checks a target named _EnsureDeviceBooted is in a property.

jonathanpeppers reviewed Mar 18, 2026

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rmarinho marked this pull request as ready for review March 18, 2026 20:37

rmarinho requested review from grendello and simonrozsival as code owners March 18, 2026 20:37

Copilot AI review requested due to automatic review settings March 18, 2026 20:37

Copilot AI reviewed Mar 18, 2026

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rmarinho force-pushed the dev/ensure-device-booted-deploy branch 2 times, most recently from aa3f844 to d188a4b Compare March 19, 2026 16:27

rmarinho mentioned this pull request Mar 19, 2026

Update copilot-instructions.md with learnings from recent PRs #10974

Merged

rmarinho force-pushed the dev/ensure-device-booted-deploy branch 2 times, most recently from 62a458e to a2787ca Compare March 19, 2026 22:45

rmarinho and others added 5 commits March 23, 2026 15:12

Fix emulator boot and deploy flow for 'dotnet run'

8ad821d

Address multiple issues preventing 'dotnet run --project' from successfully booting an Android emulator and deploying the app. Fixes: #10965 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

rmarinho force-pushed the dev/ensure-device-booted-deploy branch from 54bfb68 to 17d3f5f Compare March 23, 2026 15:13

rmarinho requested a review from jonathanpeppers March 23, 2026 16:39

jonathanpeppers reviewed Mar 23, 2026

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Fix emulator boot and deploy flow for `dotnet run`#10969

Fix emulator boot and deploy flow for `dotnet run`#10969
rmarinho wants to merge 5 commits intomainfrom
dev/ensure-device-booted-deploy

rmarinho commented Mar 18, 2026 •

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Summary

Problem & Fix

_EnsureDeviceBooted not firing during DeployToDevice

Changes

Testing

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rmarinho commented Mar 18, 2026 •

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`_EnsureDeviceBooted` not firing during `DeployToDevice`