Unable to create XUnit Project referencing .NET 8 MAUI

[owenashurst]

Description

Whenever I try and create an XUnit project targeting my .NET 8 MAUI project, the IDE shows the following error:

Severity Code Description Project File Line Suppression State Details
Error NU1201 Project MyMauiApp is not compatible with net8.0 (.NETCoreApp,Version=v8.0). Project MyMauiApp supports:

• net8.0-android34.0 (.NETCoreApp,Version=v8.0)
• net8.0-ios17.2 (.NETCoreApp,Version=v8.0)
• net8.0-maccatalyst17.2 (.NETCoreApp,Version=v8.0)
• net8.0-windows10.0.19041 (.NETCoreApp,Version=v8.0) MyMauiApp.UnitTests C:\dev\MyMauiApp\MyMauiApp .UnitTests\MyMauiApp.UnitTests.csproj 1

Steps to Reproduce

1.) Create a .NET 8 MAUI project
2.) Create an XUnit test project
3.) Reference the .NET MAUI project from the XUnit Project
4.) Observe the error

Link to public reproduction project repository

No response

Version with bug

8.0.6 SR1

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android, Windows, macOS, Other (Tizen, Linux, etc. not supported by Microsoft directly)

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[drasticactions]

This is not a bug with MAUI, the error you're getting is correct for what you're doing. See #17791 (comment)

The XUnit project is net8.0. MAUI Projects are platform projects (net8.0-android;net8.0-ios...). This is unrelated to MAUI, you would see the same error if you tried referencing other platform-specific .NET projects to a non platform specific project. This isn't a bug, it has always and will always do this.

If you want to test platform specific code, you would need an XUnit test runner that would run the code on the platform in question. If you want to test generic cross-platform code and don't need it running on the platform, then you would need to move that into another class library so you could reference it inside the generic XUnit (or whatever .NET Test framework) you have.

You could also change your MAUI csproj to add the target framework

<TargetFrameworks>net8.0;net8.0-android;net8.0-ios;net8.0-maccatalyst</TargetFrameworks>
<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net8.0-windows10.0.19041.0</TargetFrameworks>
<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
<!-- <TargetFrameworks>$(TargetFrameworks);net8.0-tizen</TargetFrameworks> -->
<OutputType Condition="'$(TargetFramework)' != 'net8.0'">Exe</OutputType>

The key is making sure that the generic code doesn't have the output type of an exe, since it can't be run that way.

@PureWeen @BretJohnson Do you have any other advice?

[RoiChen001]

Can repro this issue on the latest 17.10 Preview 2.

[owenashurst]

This is not a bug with MAUI, the error you're getting is correct for what you're doing. See #17791 (comment)

The XUnit project is net8.0. MAUI Projects are platform projects (net8.0-android;net8.0-ios...). This is unrelated to MAUI, you would see the same error if you tried referencing other platform-specific .NET projects to a non platform specific project. This isn't a bug, it has always and will always do this.

If you want to test platform specific code, you would need an XUnit test runner that would run the code on the platform in question. If you want to test generic cross-platform code and don't need it running on the platform, then you would need to move that into another class library so you could reference it inside the generic XUnit (or whatever .NET Test framework) you have.

You could also change your MAUI csproj to add the target framework

<TargetFrameworks>net8.0;net8.0-android;net8.0-ios;net8.0-maccatalyst</TargetFrameworks>
<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net8.0-windows10.0.19041.0</TargetFrameworks>
<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
<!-- <TargetFrameworks>$(TargetFrameworks);net8.0-tizen</TargetFrameworks> -->
<OutputType Condition="'$(TargetFramework)' != 'net8.0'">Exe</OutputType>

The key is making sure that the generic code doesn't have the output type of an exe, since it can't be run that way.

@PureWeen @BretJohnson Do you have any other advice?

Thank you. Adding net8.0 to the target frameworks does indeed work and adding a conditional output, however it then breaks visual studio for me. If I use Rider, I'm able to compile successfully and run my tests. The downside is I obviously lose visual studio and its UI for publishing ad hoc builds.

I have however found the command line to publish, so it's a bit of a manual task which I'm willing to do if I can actually test my business logic which is more important.

[PureWeen]

Can you elaborate on "breaks visual studio"?

[owenashurst]

Can you elaborate on "breaks visual studio"?

Sorry, was a rushed reply.

I get the following errors in the Errors tab which prevents me from building, however Rider is fine.

Project MyProject is not compatible with net8.0 (.NETCoreApp,Version=v8.0). Project MyProject does not support any target frameworks. MyProject .UnitTests C:\dev\MyProject\MyProject .UnitTests\MyProject .UnitTests.csproj

And then several errors which are the same:

Unable to read project information for 'MyProject': The property PackageVersion was expected to have a single value across all target frameworks, but instead had the following values: 0.23, 1.0.0 MyProject C:\dev\MyProject\MyProject\MyProject.csproj

If i then look at the Dependencies in the solution explorer, all of them except net8.0-android shows a yellow triangle. No matter how many times I run Clean and Rebuild, I get the same issues.

I've even tried running dotnet workload restore and I get the same issues.

[mattleibow]

Duplicate of #17791

[PureWeen]

@owenashurst if you use devkit with vscode do you get the same exception?

[mattleibow]

This is because the app TFMs are setting a project version property using the ApplicationVersion, however, plain .net 8 does not have this concept. You need to also add a <Version Condition="'$(TargetFramework)' == 'net8.0">0.23</Version>

However, this still does not mean that this is the best way to do testing. It is much better to create a shared project that just has testable items in it - pages, VMs and models. Then make that be multi-targeted.

Both the app and unit test project can then reference this singe shared project.