Microsoft.Testing.Platform: not equal operator not working in mstest runner graph query filtering

[sergey-rybalkin]

Describe the bug

Using new Microsoft.Testing.Platform library with TUnit framework. It seems like not all of the test filtering operators documented in graph query filtering are supported. For example, when using TUnit with --treenode-filter command line parameter the not equal != operator doesn't seem to be working for me.

Steps To Reproduce

Consider the following code snippet:

public class MyTests
{
    [Test]
    [Category("Smoke")]
    public void TestWithCategory()
    {
        // ...
    }

    [Test]
    public void TestWithoutCategory()
    {
        // ...
    }
}

The following command runs only the first test, as expected dotnet run --treenode-filter /*/*/*/*[Category=Smoke]:

Test run summary: Passed! - bin\Debug\net9.0\Engine.Tests.dll (net9.0|x64)
  total: 1
  failed: 0
  succeeded: 1
  skipped: 0
  duration: 91ms

However, dotnet run --treenode-filter /*/*/*/*[Category!=Smoke] doesn't seem to find anything:

Test run summary: Zero tests ran - bin\Debug\net9.0\Engine.Tests.dll (net9.0|x64)
  total: 0
  failed: 0
  succeeded: 0
  skipped: 0
  duration: 88ms

Expected behavior

Filter should exclude tests with Category property set to Smoke.

Actual behavior

Filter excludes all tests.

Additional context

Seems like filter parser doesn't support != operator at all - https://github.com/microsoft/testfx/blob/main/src/Platform/Microsoft.Testing.Platform/Requests/TreeNodeFilter/TreeNodeFilter.cs#L56
Related issue in TUnit repository - thomhurst/TUnit#1381

SDK version: 9.0.101
OS version: Microsoft Windows [Version 10.0.26100.2454]
TUnit version: 0.4.86
Microsoft.Testing.Platform version: 1.4.3

[Evangelink]

I don't recall how much was actually implemented in the current version of the tree filter but that's definitely supported by our design: https://github.com/microsoft/testfx/blob/main/docs/mstest-runner-graphqueryfiltering/graph-query-filtering.md

Hence marking this as a bug.