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

まず、LibGit2Sharp のソース内でランタイムチェックとネイティブアセンブリの解決箇所を特定します。PowerShell Core と Windows PowerShell で検索を再現し、その後、両方の環境で lib/win32/xXX フォルダーからネイティブアセンブリが見つかることを確認します。GitAutomation が PowerShell Core で LibGit2Sharp を読み込めれば完了です。