C# Dev Kit Test Explorer doesn't run tests - Incorrect format for TestCaseFilter Error: Empty parenthesis ( )

[aaronenberg]

Describe the issue

Clicking the Run Tests button to run all tests, or clicking on the top-level project item in Testing tab builds the tests but does not run them.

In Test explorer I see this error:

[error] Incorrect format for TestCaseFilter Error: Empty parenthesis ( ). Specify the correct format and try again. Note that the incorrect format can lead to no test getting executed

Collect logs

csdevkit-logs-2026-07-09T21-39-30.zip

Steps to reproduce

No response

Expected behavior

No response

Environment information

C# Dev Kit v3.20.199
Version: 1.128.0 (user setup)
Commit: fc3def6774c76082adf699d366f31a557ce5573f
Date: 2026-07-07T15:14:24-07:00
Electron: 42.5.0
ElectronBuildId: 14525058
Chromium: 148.0.7778.271
Node.js: 24.17.0
V8: 14.8.178.33-electron.0
OS: Windows_NT x64 10.0.22631

[kschalk]

Had the same problem. Workaround was to disable the 'Dotnet › Test Window: Enable Next Test (Experimental)' setting in the C# Dev Kit for both User and Workspace.