<PackageReference Include="NUnit" Version="4.3.1" />

NUnit.Framework.Internal.TestProgressReporter

public sealed class TestProgressReporter : ITestListener
TestProgressReporter translates ITestListener events into the async callbacks that are used to inform the client software about the progress of a test run.
namespace NUnit.Framework.Internal { public sealed class TestProgressReporter : ITestListener { public TestProgressReporter(ICallbackEventHandler handler); public void TestStarted(ITest test); public void TestFinished(ITestResult result); public void TestOutput(TestOutput output); public void SendMessage(TestMessage message); } }