How to Write Add-ins to Extend Visual Studio for Mac

I just shipped a test build of xUnit.net add-in at GitHub, which enables Visual Studio for Mac to run xUnit unit test cases.

So what are the steps to build such an add-in? Below I try to show some technical details.

Visual Studio for Mac

Microsoft announced this new IDE last year at Connect 2016 keynote, which is a surprise for many developers. But if we check this IDE further, easily we can see it is not a surprise at all.

• This IDE is based on MonoDevelop/Xamarin Studio, which has a very long history already.
• It reuses many useful ingredients from Visual Studio itself, such as the editor experience.

Extension Authoring

Previously to develop extensions for MonoDevelop/Xamarin Studio, we need to target the 5.x or 6.x profiles of MonoDevelop core binaries. That’s why for xUnit.net add-in there are two branches, 5.0 and 6.0.

The core assemblies have significant differences in editor related APIs, due to the big upgrade in Xamarin Studio 6.x. And now again, Visual Studio for Mac (based on MonoDevelop 7.x) requires a new branch.

So to create a new add-in, you can always get start from the official guide for Xamarin Studio,

Updated (Jan 12, 2023): This guide is no longer valid.

Extending Xamarin Studio with Add-Ins

Replace all texts of “Xamarin Studio” with “Visual Studio for Mac”, and you should be able to get Addin Maker (>=1.3.4) installed and a sample add-in created.

Note that MonoDevelop.Addins NuGet package should be upgraded to 0.3.9 and above, so that debugging add-ins can be enabled.

Finally to pack up your add-in and share with others, go to the assembly output folder to locate the add-in assembly (MonoDevelop.XUnit.dll for example), and call vstool.exe utility

mono /Applications/Visual\ Studio.app/Contents/Resources/lib/monodevelop/bin/vstool.exe setup pack MonoDevelop.XUnit.dll

Then a .mpack file would be generated and everyone can manually add it to Visual Studio for Mac once you share it publicly.

Note that once the add-in repository for Visual Studio for Mac is alive, you don’t need to share .mpack file in this way.

Now Microsoft/Xamarin has opened up the addin feed for Visual Studio for Mac, so as publisher you should use https://addins.monodevelop.com to publish your addin. Users then use the integrated Extension Manager to search and install.

Updated (Jan 12, 2023): The latest news can be found in this post