LibGit2Sharp can't find native assembly under PowerShell Core

I maintain a PowerShell module, GitAutomation, that wraps the LibGit2Sharp library. Yesterday, I was trying to get it to run on PowerShell Core. It doesn't seem to work. It is looking for the native git assembly in the LibGit2Sharp.dll assembly's folder instead of the lib/win32/xXX folder, like it does under Windows PowerShell (.NET Framework).

The issue appears to be your check for whether or not you're running under .NET Core. It looks like you're looking for the Mono.Runtime type, which doesn't exist in the version of .NET Core that PowerShell Core is using.

It looks like the current best way to determine if you're running under .NET Core is to use the System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription property, which begins with .NET Framework when running under the .NET Framework and .NET Core when running under .NET Core.

Windows PowerShell:

$ [Runtime.InteropServices.RuntimeInformation]::FrameworkDescription
.NET Framework 4.7.3260.0
$ [Mono.Runtime]
Unable to find type [Mono.Runtime].
At line:1 char:1
+ [Mono.Runtime]
+ ~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (Mono.Runtime:TypeName) [], RuntimeException
    + FullyQualifiedErrorId : TypeNotFound

PowerShell Core

 $ [Runtime.InteropServices.RuntimeInformation]::FrameworkDescription
.NET Core 4.6.26919.02
 $ [Mono.Runtime]
Unable to find type [Mono.Runtime].
At line:1 char:1
+ [Mono.Runtime]
+ ~~~~~~~~~~~~~~
+ CategoryInfo          : InvalidOperation: (Mono.Runtime:TypeName) [], RuntimeException
+ FullyQualifiedErrorId : TypeNotFound

Start by locating the runtime check and native assembly resolution in the LibGit2Sharp source. Reproduce the lookup under PowerShell Core and Windows PowerShell, then verify that the native assembly is found from the lib/win32/xXX folder in both environments. Done means GitAutomation can load LibGit2Sharp on PowerShell Core.