Unit test projects can't reference MAUI projects

[Adam--]

Description

Given a solution with a MAUI project and a unit test project, when the unit test project has a project reference to the MAUI project, I get a build error:

Project '..\MauiApp3\MauiApp3.csproj' targets 'net8.0-android;net8.0-ios;net8.0-maccatalyst;net8.0-windows10.0.19041.0'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v8.0'.

In #3552, @mattleibow mentioned that it was fixed in .NET 8 preview 2 and closed the bug, however, it is not working with 8.0,200 or 8.0.202, VS 17.9.3 or VS 17.10.0 Preview 2.0. I marked this as a regression, but I didn't attempt to validate that it worked in .NET 8 preview 2.

In his screenshot on the linked bug, he was unit testing a class library. I tried both a MAUI app and class library and got the same error.

Steps to Reproduce

1. Create a new MAUI project using Visual Studio
2. Within the solution, add a new unit test project (xUnit, NUnit)
3. Add a project reference form the unit test project to the MAUI project
4. Attempt to build the unit test project

Observed behavior:
Error: Project '..\MauiApp3\MauiApp3.csproj' targets 'net8.0-android;net8.0-ios;net8.0-maccatalyst;net8.0-windows10.0.19041.0'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v8.0'.

Link to public reproduction project repository

https://github.com/Adam--/MauiUnitTestReferenceIssue

Version with bug

8.0.7 SR2

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

8.0.0-preview.2.7871

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?

Yes!
To the MAUI app csproj:

• add ;net8.0 to the TargetFrameworks
• change the OutputType to <OutputType Condition="'$(TargetFramework)' != 'net8.0'">Exe</OutputType>
• and if needed remove the compilation of MauiProgram.cs with

  <ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
    <Compile Remove="MauiProgram.cs" />
  </ItemGroup>

I didn't need to do this last part on the example project, but on a project with handlers, I needed to.

Relevant log output

No response

[ninachen03]

Verified this issue on VS 17.10.0 Preview 2. can repro it.

<style> </style>

Severity	Code	Description	Project	File	Line	Suppression State
Error		Project '..\MauiApp3\MauiApp3.csproj' targets 'net8.0-android;net8.0-ios;net8.0-maccatalyst;net8.0-windows10.0.19041.0'. It cannot be referenced by a project that targets '.NETCoreApp,Version=v8.0'.	MauiApp3.Test	C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets	1879

[mattleibow]

Duplicate of #3552

[Adam--]

@mattleibow, as I mentioned in the description, this is still happening and appears to be a regression. @ninachen03 reproduced it too.

In #3552, @mattleibow mentioned that it was fixed in .NET 8 preview 2 and closed the bug, however, it is not working with 8.0,200 or 8.0.202, VS 17.9.3 or VS 17.10.0 Preview 2.0. I marked this as a regression, but I didn't attempt to validate that it worked in .NET 8 preview 2.

Could you please reopen this issue?