Why Nunit3 OneTimeSetUp() is called after [Test] and not before - nunit

Question

I have my unit tests written in Nunit 2.6 but planning to upgrade to Nunit 3.6.1 , however I noticed a weird problem with Nunit 3.6.1 (or may be I did not understood it correctly). The problem is around OneTimeSetUp().
In Nunit 2.6.3, I had SetUpFixtureAttribute [SetUpFixture] and inside that SetUpAttribute [SetUp] and it worked as expected for me, the flow was
SetUpFixture.Setup
TestFixture.Setup
TestFixture.Test
TestFixture.TearDown
TestFixture.Setup
TestFixture.Test
TestFixture.TearDown
SetUpFixture.TearDown
When I upgraded to Nunit 3, I replaced the SetUp() inside SetUpFixture with OneTimeSetUp, and after running my code I got following flow
TestFixture.Setup
TestFixture.Test
TestFixture.TearDown
SetUpFixture.OneTimeSetUp
SetUpFixture.OneTimeTearDown
Following is the sample code which I tried on my machine and also the command line output
[SetUpFixture]
public class TestBase
{
[OneTimeSetUp]
//[SetUp]
public static void MyTestSetup()
{
Console.WriteLine(" ---------- Calling OneTimeSetUp ----------");
}
}
[TestFixture]
class TestClass : TestBase
{
[Test]
public void test()
{
Console.WriteLine("\n ....I'm inside TestClass.test() ....");
}
}
Console Output
=> TestSample.TestClass.test
....I'm inside TestClass.test() ....
=> TestSample.TestClass
---------- Calling OneTimeSetUp ----------
=> TestSpecflow.TestBase
---------- Calling OneTimeSetUp ----------
Can someone please suggest what am i missing here ?
I'm running the test via nunit-console

Answer 1

The issue is that the output is misleading and not in the order the code is executed. Because NUnit 3 supports parallel execution, it captures output and displays it on the console when that level of test execution is completed.
In your case, the fixture setup wraps the tests, so it finishes executing after the tests and outputs the captured text afterward.
If you debug your tests, or switch your Console.WriteLine calls to TestContext.Progress.WriteLine which outputs immediately, you will see that the code is executed in the order you expect.
If it is not in the order you expect, look at the namespaces. Remember that a [SetupFixture] is used to setup at the namespace level. If your tests are in a different namespace, they may be called in a different order. If you want a setup for all of your tests, put the class in your top level namespace, or if you have multiple namespaces, in no namespace.
Here is some test code,
namespace NUnitFixtureSetup
{
[SetUpFixture]
public class SetupClass
{
[OneTimeSetUp]
public void MyTestSetup()
{
TestContext.Progress.WriteLine("One time setup");
}
}
[TestFixture]
public class TestClass
{
[Test]
public void TestMethod()
{
TestContext.Progress.WriteLine("Test Method");
}
}
}
And here is the output from running with nunit3-console.exe
=> NUnitFixtureSetup.SetupClass
One time setup
=> NUnitFixtureSetup.TestClass.TestMethod
Test Method

Answer 2

Rob's answer is the fundamental reason you have a problem, but there is an additional one, which is present in your code although not in Rob's.
In your code, you are using TestBase twice: as a SetUpFixture and as the base class for your TestFixture.
That means the OneTimeSetUp method will be used twice... Once before all the fixtures in the namespace and once before any test fixture that inherits from it. Using a SetUpFixture in this way defeats it's purpose, which is to have some code that runs only once before all the fixtures in a namespace.
Use separate classes as a base class (if you need one) and as a setup fixture (if you need one of those).