Lifecycle.cs

using NUnit.Framework;

[SetUpFixture]
public class RootFixtureSetup
{
    [OneTimeSetUp]
    public void OneTimeSetUp() => TestContext.Progress.WriteLine("RootFixtureSetup:OneTimeSetUp");

    [OneTimeTearDown]
    public void OneTimeTearDown() => TestContext.Progress.WriteLine("RootFixtureSetup:OneTimeTearDown");
}

namespace TestLifeCycle
{
    [SetUpFixture]
    public class FixtureSetup
    {
        [OneTimeSetUp]
        public void OneTimeSetUp() => TestContext.Progress.WriteLine("FixtureSetup:OneTimeSetUp");

        [OneTimeTearDown]
        public void OneTimeTearDown() => TestContext.Progress.WriteLine("FixtureSetup:OneTimeTearDown");
    }

    [TestFixture]
    public class Tests
    {
        [OneTimeSetUp]
        public void OneTimeSetUp() => TestContext.Progress.WriteLine("Tests:OneTimeSetUp");

        [SetUp]
        public void Setup() => TestContext.Progress.WriteLine("Tests:SetUp");

        public Tests() => TestContext.Progress.WriteLine("Tests:Constructor");

        [Test]
        public void Test1() => TestContext.Progress.WriteLine("Tests:Test1");

        [Test]
        public void Test2() => TestContext.Progress.WriteLine("Tests:Test2");

        [TearDown]
        public void TearDown() => TestContext.Progress.WriteLine("Tests:TearDown");

        [OneTimeTearDown]
        public void OneTimeTearDown() => TestContext.Progress.WriteLine("Tests:OneTimeTearDown");
    }
}

RootFixtureSetup:OneTimeSetUp
FixtureSetup:OneTimeSetUp
Tests:Constructor
Tests:OneTimeSetUp
Tests:SetUp
Tests:Test1
Tests:TearDown
Tests:SetUp
Tests:Test2
Tests:TearDown
Tests:OneTimeTearDown
FixtureSetup:OneTimeTearDown
RootFixtureSetup:OneTimeTearDown
NUnit Adapter 3.16.1.0: Test execution complete
----- Test Execution Summary -----

TestLifeCycle.Tests.Test1:
    Outcome: Passed
    
TestLifeCycle.Tests.Test2:
    Outcome: Passed
    
Total tests: 2. Passed: 2. Failed: 0. Skipped: 0