Add -NoCoverage switch and improve crash diagnostics

tools/artifacts/testResults.ps1

@@ -4,21 +4,25 @@ Param(
 
 $result = @{}
 
+# Hang and crash dumps are copied into the TRX attachment directory when a TRX report is requested.
+# Prefer that copy to avoid uploading the same dump twice, but keep the original when no attachment
+# copy exists (e.g. GitHub Actions runs, which don't request a TRX report) so crashes stay diagnosable.
+function Select-TestResultFile($files) {
+    $attachedDumpNames = @($files | Where-Object { $_.Extension -eq '.dmp' -and $_.FullName -match '[/\\]In[/\\]' } | ForEach-Object { $_.Name })
+    $files | Where-Object { $_.Extension -ne '.dmp' -or $_.FullName -match '[/\\]In[/\\]' -or $attachedDumpNames -notcontains $_.Name }
+}
+
 $RepoRoot = Resolve-Path "$PSScriptRoot\..\.."
 $testRoot = Join-Path $RepoRoot test
 $legacyTestResults = Join-Path $testRoot TestResults
 if (Test-Path $legacyTestResults) {
-    $result[$testRoot] = Get-ChildItem $legacyTestResults -Recurse -Directory |
-        Get-ChildItem -Recurse -File |
-        Where-Object { $_.Extension -ne '.dmp' -or $_.FullName -match '[/\\]In[/\\]' }
+    $result[$testRoot] = Select-TestResultFile @(Get-ChildItem $legacyTestResults -Recurse -Directory | Get-ChildItem -Recurse -File)
 }
 
 $artifactStaging = & "$PSScriptRoot/../Get-ArtifactsStagingDirectory.ps1"
 $testlogsPath = Join-Path $artifactStaging "test_logs"
 if (Test-Path $testlogsPath) {
-    # Hang and crash dumps are copied into the TRX attachment directory.
-    $result[$testlogsPath] = Get-ChildItem $testlogsPath -Recurse |
-        Where-Object { $_.Extension -ne '.dmp' -or $_.FullName -match '[/\\]In[/\\]' }
+    $result[$testlogsPath] = Select-TestResultFile @(Get-ChildItem $testlogsPath -Recurse)
 }
 
 $result

tools/dotnet-test-cloud.ps1

@@ -13,14 +13,17 @@
     A switch to run the tests in an x86 process.
 .PARAMETER dotnet32
     The path to a 32-bit dotnet executable to use.
+.PARAMETER NoCoverage
+    A switch to skip code coverage collection.
 #>
 [CmdletBinding()]
 Param(
     [string]$Configuration='Debug',
     [string]$Agent='Local',
     [switch]$PublishResults,
     [switch]$x86,
-    [string]$dotnet32
+    [string]$dotnet32,
+    [switch]$NoCoverage
 )
 
 $RepoRoot = (Resolve-Path "$PSScriptRoot/..").Path
@@ -60,23 +63,32 @@ if ($isMTP) {
         ,'--hangdump'
         ,'--hangdump-timeout','120s'
         ,'--crashdump'
+        ,'--crashdump-type','Heap'
+        # The native crash report accompanies the dump and is often the only way to identify the
+        # faulting thread and instruction when a test host dies of an access violation on Linux.
+        ,'--crash-report-if-supported'
     )
     $mtpArgs = @(
-        ,'--coverage'
-        ,'--coverage-output-format','cobertura'
         ,'--diagnostic'
         ,'--diagnostic-output-directory',$testLogs
         ,'--diagnostic-verbosity','Information'
         ,'--results-directory',$testLogs
         ,'--report-trx'
     )
 
+    if (-not $NoCoverage) {
+        $mtpArgs += @(
+            ,'--coverage'
+            ,'--coverage-output-format','cobertura'
+            ,'--coverage-settings',"$PSScriptRoot/test.runsettings"
+        )
+    }
+
     & $dotnet test --solution $RepoRoot `
         --no-build `
         -c $Configuration `
         -bl:"$testBinLog" `
         --filter-not-trait 'TestCategory=FailsInCloudTest' `
-        --coverage-settings "$PSScriptRoot/test.runsettings" `
         @mtpArgs `
         @dumpSwitches `
         @extraArgs
@@ -85,17 +97,24 @@ if ($isMTP) {
     $trxFiles = Get-ChildItem -Recurse -Path $testLogs\*.trx
 } else {
     $testDiagLog = Join-Path $ArtifactStagingFolder (Join-Path test_logs diag.log)
+    $coverageArgs = @()
+    if (-not $NoCoverage) {
+        $coverageArgs = @(
+            ,'--collect','Code Coverage;Format=cobertura'
+            ,'--settings',"$PSScriptRoot/test.runsettings"
+        )
+    }
+
     & $dotnet test $RepoRoot `
         --no-build `
         -c $Configuration `
         --filter "TestCategory!=FailsInCloudTest" `
-        --collect "Code Coverage;Format=cobertura" `
-        --settings "$PSScriptRoot/test.runsettings" `
         --blame-hang-timeout 60s `
         --blame-crash `
         -bl:"$testBinLog" `
         --diag "$testDiagLog;TraceLevel=info" `
         --logger trx `
+        @coverageArgs `
         @extraArgs
     if ($LASTEXITCODE -ne 0) { $failedTests += 1 }