[flaky-ci] Recover MAUI R2R Helix device failures

build-tools/automation/scripts/RunMauiR2RHelix.Tests.Process.ps1

@@ -0,0 +1,50 @@
+$ErrorActionPreference = 'Stop'
+
+$testScript = Join-Path $PSScriptRoot 'RunMauiR2RHelix.Tests.ps1'
+$powerShell = Get-Command 'pwsh' -ErrorAction Stop
+$testRoot = Join-Path ([IO.Path]::GetTempPath()) "Maui R2R process $([IO.Path]::GetRandomFileName())"
+$testsPassed = $false
+
+function Invoke-TestProcess ([string] $Name, [string []] $AdditionalArguments)
+{
+	$stdoutPath = Join-Path $testRoot "$Name.out.log"
+	$stderrPath = Join-Path $testRoot "$Name.err.log"
+	$arguments = @('-NoLogo', '-NoProfile', '-File', "`"$testScript`"") + $AdditionalArguments
+	$process = Start-Process -FilePath $powerShell.Source -ArgumentList $arguments -RedirectStandardOutput $stdoutPath -RedirectStandardError $stderrPath -NoNewWindow -PassThru
+	# Windows PowerShell requires the process handle to be cached before waiting when output is redirected.
+	$null = $process.Handle
+	$process.WaitForExit()
+
+	return [pscustomobject]@{
+		ExitCode = $process.ExitCode
+		StandardOutput = [string](Get-Content -LiteralPath $stdoutPath -Raw -ErrorAction Ignore)
+		StandardError = [string](Get-Content -LiteralPath $stderrPath -Raw -ErrorAction Ignore)
+	}
+}
+
+try {
+	New-Item -ItemType Directory -Path $testRoot | Out-Null
+
+	$success = Invoke-TestProcess 'success' @()
+	if ($success.ExitCode -ne 0) {
+		throw "The successful MAUI R2R Helix suite exited with code $($success.ExitCode). Output:`n$($success.StandardOutput)`n$($success.StandardError)"
+	}
+	Write-Host $success.StandardOutput.TrimEnd()
+
+	$failure = Invoke-TestProcess 'injected-failure' @('-InjectAssertionFailure')
+	if ($failure.ExitCode -eq 0) {
+		throw 'The injected MAUI R2R Helix assertion failure unexpectedly exited with code 0.'
+	}
+	if ($failure.StandardError -notmatch 'Injected process-level assertion failure') {
+		throw "The injected MAUI R2R Helix assertion failure did not report the expected error. Output:`n$($failure.StandardOutput)`n$($failure.StandardError)"
+	}
+
+	Write-Host 'MAUI R2R Helix process exit-code tests passed.'
+	$testsPassed = $true
+} finally {
+	Remove-Item -LiteralPath $testRoot -Recurse -Force -ErrorAction Ignore
+}
+
+if ($testsPassed) {
+	exit 0
+}