Get NuGet package folder in MSBuild - msbuild

Question

I want to call executable tools like NUnit which I manage via NuGet in MSBuild:
<Target Name="Test">
<CreateItem Include="$(BuildCompileDirectory)\*.Tests.*dll">
<Output TaskParameter="Include" ItemName="TestAssemblies" />
</CreateItem>
<NUnit
Assemblies="#(TestAssemblies)"
ToolPath="$(PackagesDirectory)\NUnit.2.5.10.11092\tools"
WorkingDirectory="$(BuildCompileDirectory)"
OutputXmlFile="$(BuildDirectory)\$(SolutionName).Tests.xml" />
</Target>
The problem is that the folder of a NuGet packages is containing the version number of the package. For instance nunit-console.exe is in the folder packages\NUnit.2.5.10.11092\tools. If I update the NUnit package this path will change and I have to update my MSBuild script. That isn't acceptable.
MSBuild doesn't allow Wildcards in directories, so this isn't working:
ToolPath="$(PackagesDirectory)\NUnit.*\tools"
How can I call tools in MSBuild without having to update my build script whenever I update a NuGet package?

Answer 1

You can use MSBuild Transforms to get the relative directory of a specific tool:
<ItemGroup>
<NunitPackage Include="$(PackagesDirectory)\NUnit.*\tools\nunit-console.exe"/>
</ItemGroup>
<Target Name="Test">
<CreateItem Include="$(BuildCompileDirectory)\*.Tests.*dll">
<Output TaskParameter="Include" ItemName="TestAssemblies" />
</CreateItem>
<NUnit
Assemblies="#(TestAssemblies)"
ToolPath="#(NunitPackage->'%(relativedir)')"
WorkingDirectory="$(BuildCompileDirectory)"
OutputXmlFile="$(BuildDirectory)\$(SolutionName).Tests.xml" />
</Target>

Answer 2

The comment of Mike Rosoft links to Patrik Svensson his blog post and it helped me as follows:
Add GeneratePathProperty="true" to PackageReference of the NuGet package you want to have the location of.
Use it as $(PkgPackage_Name) whereby the dots are replaced by an underscore. Note the Pkg prefix.
This example forces Nswag to use the 32 bit dotnet.exe by overwriting the existing NSwagExe_Net60 property. This was necessary on an x86 project.
<PropertyGroup>
<NSwagExe_Net60>"$(MSBuildProgramFiles32)\dotnet\dotnet.exe" "$(PkgNSwag_MSBuild)\tools\Net60\dotnet-nswag.dll"</NSwagExe_Net60>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="NSwag.MSBuild" Version="13.16.1" GeneratePathProperty="true">
</ItemGroup>