Could not load type 'System.Threading.Lock' from assembly 'Microsoft.VisualStudio.TestPlatform.TestFramework, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

[Evangelink]

Describe the bug

Tests are crashing when targeting net9.0 WinUI for all MSTest 3.7. Tests are running well for 3.6.4 and lower

Investigation

In 3.7.0, we added support for net9.0 but the target is loading the winui platform services from net6.0 which is causing a mismatch in signature for the location of Lock.

[ghord]

Can confirm that downgrading MsTest.TestAdapter to version 3.6.4 fixed the issue for me. I was not able to run any winui3 tests on .net9 on versions 3.7+. Thanks for the workaround hint.

[Evangelink]

We will ship the fix next week

[Evangelink]

Fixed by #4793. I'll add some acceptance test to reduce chances of regression.