MSBuild get assembly names of tests

I'm working on generating coverage. One of the tests was taking a long time if the OpenCover filter was just +[*] so I've decided to add the assembly names. But this isn't an efficient approach as the assemblies may increase. I want to do something like extract the assembly name from UnitTestAssemblies and pass it on to filters as argument with the brackets and all.

The UnitTestAssembly.Filename gives Assembly1.Tests and I want the Assembly1 to be added as filter.

<ItemGroup>
   <UnitTestAssemblies Include="$(ProjectRoot)\**\bin\$(Configuration)\*.Tests.dll" />
</ItemGroup>


<Exec Command="$(OpenCoverToolPath)\OpenCover.Console.exe 
                -target:$(NUnitToolPath)\nunit3-console.exe 
                -register
                -targetargs:%(UnitTestAssemblies.FullPath) 
                -filter:&quot;+[Assembly1]* +[Assembly2]*&quot;
                -output:$(somepath)\%(UnitTestAssemblies.Filename).coverage.xml" 
              ContinueOnError="true" Timeout="1800000"/>

I amn't sure if this approach is efficient but this worked for me.

<ItemGroup>
   <UnitTestAssemblies>
      <AssemblyName>+[$([System.String]::Copy('%(Filename)').Replace('.Tests', ''))]*</AssemblyName>
   <UnitTestAssemblies>
</ItemGroup>

<PropertyGroup>
   <AssemblyFilters>@(UnitTestAssemblies->'%(AssemblyName)'->Distinct(), ' ')</AssemblyFilters>
<PropertyGroup>

Then I passed $(AssemblyFilters) as argument. -filters:"$(AssemblyFilters)"