Console output from application is logged as warnings

Summary

When writing console output from the application under test, the output is displayed as a warning in the Visual Studio Test Explorer. This holds true both for the standard output stream (Console.Out.Write()) as well as for the standard error stream (Console.Error.Write()).

internal class Program
{
    internal static void Main(string[] args)
    {
        Console.WriteLine("Hello, World!");
        Console.Error.WriteLine("Hello, error stream!");
    }
}

Steps to reproduce

1. Create a .NET console application project (“MyApp”)
2. Change the protection level of the Main method from implicit private to internal
3. Write to the standard output and/or standard error stream from within the Main method
4. Create an NUnit test project (“MyApp.Tests”)
5. Add a project reference from the test project to the application project
6. Make internals of the application project visible to the test project by editing MyApp.csproj:

   <ItemGroup>
     <InternalsVisibleTo Include="MyApp.Tests"/>
   </ItemGroup>
   

7. Add invocation of the Main method to the default test case:

   [Test]
   public void Test1()
   {
       Program.Main(new string[] { });
       Assert.Pass();
   }
   

8. Run the tests in Visual Studio’s Test Explorer
9. Observe the reported warning(s) in the Test Explorer

Version information

• NUnit 3.13.3
• NUnit3TestAdapter 4.4.2
• Visual Studio Community 2022 (64-bit), version 17.5.0
• Target framework: .NET 6.0

[OsirisTerje]

I think the reason is historical. There was something many years ago that only error streams were displayed, so that started it. And in order not to break people who used that to get stuff into their CI logs, we kept it that way, but added the ConsoleOut. The default however, should have been changed, as you point out, so next breaking version I’ll get that done 😃

[OsirisTerje]

That was weird. I’ll check this out! Thanks for checking this with MSTest.