nunit : global variable initialisation in setupfixture - nunit

Question

I am very new to C# and nunit. Pls bear with me if this is basic and has been already been asked here.
We have a global setup,defined by [SetupFixture] class,which is expected to be run only once. The private variables are defined in it's [setup]. We wish to use the same variables in all our testfixtures,hence inheriting the testbase class in all our testfixtures.
But, while executing Testcase1, i observe that globalSetup() is called more than once. Can anyone point me the issue? sample code is as below.
namespace CTB
{
[SetupFixture]
public class Testbase
{
private byte val1;
private byte val2;
[setup]
public void globalSetup
{
val1 = 5;
val2 = 10;
}
[Teardown]
public void globalTeardown
{
//
}
}
}
namespace CTB.Testcase
{
public class TestCase : Testbase
{
[Setup]
public void Setup()
{
}
[Teardown]
public void Teardown()
{
}
[Test]
public void Testcase1()
{
byte val3 = val1 + val2; // Expect 15
}
}
}

Answer 1

I'm assuming that the answer to my comment is "No" and that you are using a current version of NUnit 3. Please correct me if I'm wrong. :-)
You have made the class TestBase serve two functions:
It's the base class for your TestFixture and therefore it's a TestFixture itself.
It's marked as a SetUpFixture so it also serves that function - a completely different function, by the way.
To be clear, you should never do this. It's a sort of "trick" that almost seems designed to confuse NUnit - not your intention of course. Your test fixtures should have no inheritance relationship with any SetUpFixture. Use different classes for the test fixture base and the setup fixture.
With that out of the way, here is the longer story of what is happening...
Before your tests even execute, the SetUpFixture is first "run" - in quotes because it actually does nothing. That's because it doesn't contain any methods marked with [OneTimeSetUp] or '[OneTimeTearDown]`.
NOTE: As an alternate explanation, if you are using a pretty old version of NUnit, the [SetUp] and [TearDown] methods are actually called at this point. Nnit V2 used those attributes with different meanings when encountered in a SetUpFixture versus a TestFixture.
Next your tests execute. Before each test, the inherited [SetUp] and [TearDown] methods are run. Of course, these are actually the same methods as in step 1. NUnit has been tricked into doing this!
Here is some general guidance for the future...
If you want multiple fixtures to use the same data, a base class is useful. Any public or protected fields or properties will be shared by the inheriting fixtures.
If you want to do some common setup or teardown for a group of unrelated test fixtures, use a SetUpFixture. Note that the only way to pass data from a SetUpFixture to the test fixtures is through static fields or properties. Generally, you use a SetUpFixture to set up the environment in which the test is run, not to provide data.
Never use the same class for both purposes.