System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle failing in CI

[jakobbotsch]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1144025
Build error leg or test failing: System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
Pull request: #119528

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": ["System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle", "Assert.True() Failure", "Expected: True"],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1144025
Error message validated: [System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle Assert.True() Failure Expected: True]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 9/10/2025 12:16:36 PM UTC

Report

Build	Definition	Test	Pull Request
1344644	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#124544
1344588	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125821
1344101	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
1342209	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125758
1341738	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#124770
1341721	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125742
1341628	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
1340451	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125706
1338820	dotnet/runtime	System.Diagnostics.Process.Tests.WorkItemExecution	#125643
1338310	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
1338029	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125536
2927142	dotnet-runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
1335924	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125549
2926750	dotnet-runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle
1334315	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#124770
1333635	dotnet/runtime	System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle	#125416

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
3	15	16

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle tests failing #100647
• System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle failing in CI #89842

[adamsitnik]

It's a flaky test that fails once per year (see #100647 and #89842), so for now I am moving it to Future and removing "blocking-clean-ci"

[JulieLeeMSFT]

Failed in:

• runtime-coreclr libraries-jitstressregs 20260315.1

Console Log: Console Log

Failed tests:

- net11.0-windows-Release-x64-jitstressregs3-Windows.10.Amd64.Open
- net11.0-windows-Release-x86-jitstressregs2-Windows.10.Amd64.Open
  - System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle

Error Message:

    System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(windowStyle: Normal, useShellExecute: True) [FAIL]
      Assert.True() Failure

Stack Trace:

        /_/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs(118,0): at System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(ProcessWindowStyle windowStyle, Boolean useShellExecute)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(174,0): at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)

[adamsitnik]

I took a look at this test today, it starts a process using remote executor, checks if specific flag was enabled and then just exits.

To my surprise it seems to be timing out, because this line fails:

runtime/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs

Line 118 in 37c9693

Assert.True(p.WaitForExit(WaitInMS));

The interesting thing is that it happens only for useShellExecute: True.

Details

  Starting:    System.Diagnostics.Process.Tests (parallel test collections = on [4 threads], stop on fail = off)
    System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(windowStyle: Normal, useShellExecute: True) [FAIL]
      Assert.True() Failure
      Expected: True
      Actual:   False
      Stack Trace:
        /_/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs(118,0): at System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(ProcessWindowStyle windowStyle, Boolean useShellExecute)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(174,0): at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
    System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(windowStyle: Hidden, useShellExecute: True) [FAIL]
      Assert.True() Failure
      Expected: True
      Actual:   False
      Stack Trace:
        /_/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs(118,0): at System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(ProcessWindowStyle windowStyle, Boolean useShellExecute)
           at InvokeStub_ProcessStartInfoTests.TestWindowStyle(Object, Span`1)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(136,0): at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
    System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(windowStyle: Minimized, useShellExecute: True) [FAIL]
      Assert.True() Failure
      Expected: True
      Actual:   False
      Stack Trace:
        /_/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs(118,0): at System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(ProcessWindowStyle windowStyle, Boolean useShellExecute)
           at InvokeStub_ProcessStartInfoTests.TestWindowStyle(Object, Span`1)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(136,0): at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   System.Diagnostics.Process.Tests: [Long Running Test] 'System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle', Elapsed: 00:02:02
    System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(windowStyle: Maximized, useShellExecute: True) [FAIL]
      Assert.True() Failure
      Expected: True
      Actual:   False
      Stack Trace:
        /_/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs(118,0): at System.Diagnostics.Tests.ProcessStartInfoTests.TestWindowStyle(ProcessWindowStyle windowStyle, Boolean useShellExecute)
           at InvokeStub_ProcessStartInfoTests.TestWindowStyle(Object, Span`1)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(136,0): at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
    System.Diagnostics.Tests.ProcessStartInfoTests.ShellExecute_Nano_Fails_Start [SKIP]
      Condition(s) not met: "IsWindowsNanoServer"
    System.Diagnostics.Tests.ProcessTests.NonElevatedUser_QueryProcessNameOfSystemProcess [SKIP]

And for shell execute we just want to verify that it has not set anything:

runtime/src/libraries/System.Diagnostics.Process/tests/ProcessStartInfoTests.Windows.cs

Lines 98 to 99 in 37c9693

	// UseShellExecute always sets the flag but no shell does not for Normal.
	_ => useShellExecute ? (1, 1) : (0, 0),

I believe it's testing ShellExecute sys-call implementation which gives us no value. The ShellExecute logic should be simply removed from it.