Add ability to print live output messages in Test Explorer/`dotnet test` output

[bradwilson]

This adds the ability to show output messages in real time, which may assist in debugging a test which is long-running.

[bradwilson]

Available in 2.8.1-pre.4 https://xunit.net/docs/using-ci-builds

Documentation has been updated on enabling this feature:

• Via xunit.runner.json file: https://xunit.net/docs/configuration-files#showLiveOutput
• Via RunSettings: https://xunit.net/docs/runsettings#ShowLiveOutput

Using this example test:

using Xunit;
using Xunit.Abstractions;

namespace Empty;

public class TestClass(ITestOutputHelper helper)
{
    [Fact]
    public void TestMethod()
    {
        helper.WriteLine("This is a line of output");
    }
}

Output for dotnet test requires passing --logger console;verbosity=normal to that VSTest does not hide the output from xUnit.net:

Output for Test Explorer is in the Output Window, under the Tests tab:

[Piedone]

That was quick, thank you!

[Piedone]

Is there any reason not to always enable this, at least in CI? Does it have a noticable impact on performance, for example?

[bradwilson]

There should be no significant performance impact. It's not enabled by default because it's really a debugging tool more than anything else, and live printing output messages makes the output significantly more cluttered (especially with tests running in parallel that are all outputting messages).

[Piedone]

I see, thanks.