9.2: Have to add `<IsAspireHost>false</IsAspireHost>` to test project

[afscrome]

After upgrading my test project from 9.1 to 9.2, my test project refused to compile with the following error:

The type or namespace name 'ABC' does not exist in the namespace 'XYZ' (are you missing an assembly reference?)

Looking in the logs, I had a bunch of warnings of the following

'..\MY.INTEGRATION\MY.INTEGRATION.csproj' is referenced by an Aspire Host project, but it is not an executable. Did you mean to set IsAspireProjectResource="false"?

To fix this, I had to explicitly add <IsAspireHost>false</IsAspireHost> into my project - presumably a side effect of #8144 .

1. Can the SDK not automatically set IsAspireHost for a test project?
2. If not, does this need to be highlighted in the upgrade docs that tests may now need to explicitly set <IsAspireHost>false</IsAspireHost>.

For reference, here is my test csproj.

<Project Sdk="Microsoft.NET.Sdk">

    <Sdk Name="Aspire.AppHost.Sdk" Version="9.1.0" />
    <!--<Sdk Name="Aspire.AppHost.Sdk" Version="9.2.0-preview.1.25205.2" />-->
    <PropertyGroup>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
        <IsPackable>false</IsPackable>
        <IsTestProject>true</IsTestProject>
        <!-- Have to add the following with 9.2 -->
        <!--<IsAspireHost>false</IsAspireHost> -->
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Aspire.Hosting.AppHost" />
        <PackageReference Include="Aspire.Hosting.Testing" />
        <PackageReference Include="coverlet.collector">
          <PrivateAssets>all</PrivateAssets>
          <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
        </PackageReference>
        <PackageReference Include="Extensions.Logging.NUnit" />
        <PackageReference Include="Microsoft.NET.Test.Sdk" />
        <PackageReference Include="NUnit" />
        <PackageReference Include="NUnit.Analyzers">
          <PrivateAssets>all</PrivateAssets>
          <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
        </PackageReference>
        <PackageReference Include="NUnit3TestAdapter" />
        <PackageReference Include="prometheus-net.AspNetCore" />
    </ItemGroup>

    <ItemGroup>
      <ProjectReference Include="..\MYINTEGRATION\MY.INTEGRATION.csproj" />
      <!-- … Several more project references ... -->
    </ItemGroup>

    <ItemGroup>
        <Using Include="System.Net" />
        <Using Include="Microsoft.Extensions.DependencyInjection" />
        <Using Include="Aspire.Hosting.ApplicationModel" />
        <Using Include="Aspire.Hosting.Testing" />
        <Using Include="NUnit.Framework" />
    </ItemGroup>

</Project>

[danmoseley]

@DamianEdwards ?

[DamianEdwards]

Not sure. @ReubenBond @joperezr?

[joperezr]

Hey @afscrome, can you help me understand why do you reference the apphost sdk if this project is not meant to be used as an apphost? To answer your question, the new sdk will now always set 'IsAspireHost' to true starting from 9.2, but that is because you should only reference this SDK from AppHost projects. Is your test project not meant to be treated as an apphost? And if not, why do you need to reference the SDK?

[afscrome]

I'm writing tests for custom internal Aspire integrations, and not an App Host specifically. This means I am using DistributedApplicationTestingBuilder.Create() for testing rather than DistributedApplicationTestingBuilder.CreateAsync<TagHelperServicesExtensions>().

It's not an AppHost and I don't really want the SDK, but if I don't reference it, then tests fail to run - see #7808 - so I am referencing the sdk to purely to appease the requirements of DistributedApplicationTestingBuilder.Create().

Aspire.Hosting.Testing.csproj does the same thing of setting IsAspireHost to false -

aspire/src/Aspire.Hosting.Testing/Aspire.Hosting.Testing.csproj

Line 11 in 5f9a547

<IsAspireHost>false</IsAspireHost>

[joperezr]

You should still be able to reference the Apphost package without having to use the SDK, correct? I know it's confusing as they have similar names, but the NuGet package you need is a regular package reference: Aspire.Hosting.AppHost while the other one is the SDK Aspire.AppHost.Sdk. For your purposes I'd expect you to use the former but not the latter.

[afscrome]

The error is misleading, whilst the text is Ensure that your project references 'Aspire.Hosting.AppHost', the only way to make the error go away is to reference Aspire.AppHost.Sdk

The error itself is somewhat nonsensical - it is thrown from

aspire/src/Aspire.Hosting.Testing/DistributedApplicationTestingBuilder.cs

Line 332 in dbd0026

throw new InvalidOperationException("No application host assembly was found. Ensure that your project references 'Aspire.Hosting.AppHost'.");

However that project has a reference to Aspire.Hosting.AppHost so it should be impossible to be using DistributedApplicationTestingBuilder without having a reference to Aspire.Hosting.AppHost

aspire/src/Aspire.Hosting.Testing/Aspire.Hosting.Testing.csproj

Line 20 in dbd0026

<ProjectReference Include="..\Aspire.Hosting.AppHost\Aspire.Hosting.AppHost.csproj" />

[joperezr]

I see, we should figure out what it is that you need from the Apphost package that is only in the SDK, as it should be fine to use the apphost package on its own. Do you have a minimal repro that we can take a look at?

[afscrome]

Pretty sure this csproj came from one of the aspire starter templates

    [Test]
    public async Task SomeTest()
    {
        var builder = DistributedApplicationTestingBuilder.Create();

        var app = builder.Build();

        await app.StartAsync();
    }

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <IsPackable>false</IsPackable>
    <IsTestProject>true</IsTestProject>
  </PropertyGroup>

  <ItemGroup>
	<PackageReference Include="Aspire.Hosting.Testing" Version="9.2.0" />
    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.2.0" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
    <PackageReference Include="NUnit" Version="4.2.2" />
    <PackageReference Include="NUnit.Analyzers" Version="4.2.0"  />
    <PackageReference Include="NUnit3TestAdapter" Version="5.0.0" />
  </ItemGroup>

  <ItemGroup>
    <Using Include="System.Net" />
    <Using Include="Microsoft.Extensions.DependencyInjection" />
    <Using Include="Aspire.Hosting.ApplicationModel" />
    <Using Include="Aspire.Hosting.Testing" />
    <Using Include="NUnit.Framework" />
  </ItemGroup>

</Project>

Result

  Message: 
System.InvalidOperationException : No application host assembly was found. Ensure that your project references 'Aspire.Hosting.AppHost'.

  Stack Trace: 
TestingBuilder.<CreateInnerBuilder>g__FindApplicationAssembly|3_2()
<>c__DisplayClass3_0.<CreateInnerBuilder>b__0(DistributedApplicationOptions applicationOptions, HostApplicationBuilderSettings hostBuilderOptions)
Object>>.OnNext(KeyValuePair`2 value)
DiagnosticListener.Write(String name, Object value)
DiagnosticSource.Write[T](String name, T value)
DistributedApplicationBuilder.LogBuilderConstructing(DistributedApplicationOptions appBuilderOptions, HostApplicationBuilderSettings hostBuilderOptions)
DistributedApplicationBuilder.ctor(DistributedApplicationOptions options)
DistributedApplicationBuilder.ctor(String[] args)
TestingBuilderFactory.CreateBuilder(String[] args, Action`2 onConstructing)
TestingBuilder.CreateInnerBuilder(String[] args, Action`2 configureBuilder)
TestingBuilder.ctor(String[] args, Action`2 configureBuilder)
DistributedApplicationTestingBuilder.Create(String[] args, Action`2 configureBuilder)
DistributedApplicationTestingBuilder.Create(String[] args)
WebTests.Test() line 10
GenericAdapter`1.GetResult()
AsyncToSyncAdapter.Await[TResult](Func`1 invoke)
AsyncToSyncAdapter.Await(Func`1 invoke)
TestMethodCommand.RunTestMethod(TestExecutionContext context)
TestMethodCommand.Execute(TestExecutionContext context)
<>c__DisplayClass3_0.<PerformWork>b__0()
<>c__DisplayClass1_0`1.<DoIsolated>b__0(Object _)
ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
ContextUtils.DoIsolated(ContextCallback callback, Object state)
ContextUtils.DoIsolated[T](Func`1 func)
SimpleWorkItem.PerformWork()