NUnit extension

Question

Hi All i have a question regarding NUnit Extension (2.5.10). What i am trying to do is write some additional test info to the database. For that i have created NUnit extension using Event Listeners. The problem i am experiencing is that public void TestFinished(TestResult result) method is being called twice at runtime. And my code which writes to the database is in this method and that leaves me with duplicate entries in the database. The question is: Is that the expected behaviour? Can i do something about it? The extension code is below. Thanks.

using System;
using NUnit.Core;
using NUnit.Core.Extensibility;

namespace NuinitExtension
{
[NUnitAddinAttribute(Type = ExtensionType.Core,
                     Name = "Database Addin", 
                     Description = "Writes test results to the database.")]
public class MyNunitExtension : IAddin, EventListener
{
    public bool Install(IExtensionHost host)
    {
        IExtensionPoint listeners = host.GetExtensionPoint("EventListeners");
        if (listeners == null)
            return false;

        listeners.Install(this);
        return true;
    }

    public void RunStarted(string name, int testCount){}
    public void RunFinished(TestResult result){}
    public void RunFinished(Exception exception){}
    public void TestStarted(TestName testName){}

    public void TestFinished(TestResult result)
    {
        // this is just sample data
        SqlHelper.SqlConnectAndWRiteToDatabase("test", test", 
                                               2.0, DateTime.Now);
    }

    public void SuiteStarted(TestName testName){}
    public void SuiteFinished(TestResult result){}
    public void UnhandledException(Exception exception){}
    public void TestOutput(TestOutput testOutput){}
}

}

Answer 1

I have managed to fix the issue by simply removing my extension assembly from NUnit 2.5.10\bin\net-2.0\addins folder. At the moment everything works as expected but i am not sure how. I thought that you have to have the extension/addin assembly inside the addins folder. I am running tests by opening a solution via NUnit.exe. My extension project is part of the solution i am testing. I have also raised this issue with NUnit guys and got the following explanation:

Most likely, your addin was being loaded twice. In order to make it easier to test addins, NUnit searches each test assembly for addins to be loaded, in addition to searching the addins directory. Normally, when you are confident that your addin works, you should remove it from the test assembly and install it in the addins folder. This makes it available to all tests that are run using NUnit. OTOH, if you really only want the addin to apply for a certain project, then you can leave it in the test assembly and not install it as a permanent addin. http://groups.google.com/group/nunit-discuss/browse_thread/thread/c9329129fd803cb2/47672f15e7cc05d1#47672f15e7cc05d1

Answer 2

Not sure this answer is strictly relevant but might be useful.

I was having a play around with the NUnit library recently to read NUnit tests in so they could easily be transfered over to our own in-house acceptance testing framework.

It turns out we probably wont stick with this but thought it might be useful to share my experiences figuring out how to use the NUnit code:

It is different in that it doesn't get run by the NUnit console or Gui Runner but just by our own console app.

public class NUnitTestReader
{
    private TestHarness _testHarness;

    public void AddTestsTo(TestHarness testHarness)
    {
        _testHarness = testHarness;
        var package = new TestPackage(Assembly.GetExecutingAssembly().Location){AutoBinPath = true};
        CoreExtensions.Host.InitializeService();
        var testSuiteBuilder = new TestSuiteBuilder();
        var suite = testSuiteBuilder.Build(package);

        AddTestsFrom(suite);
    }

    private void AddTestsFrom(Test node)
    {
        if (!node.IsSuite)
            AddTest(node);
        else
        {
            foreach (Test test in node.Tests)
                AddTestsFrom(test);
        }
    }

    private void AddTest(Test node)
    {
        _testHarness.AddTest(new WrappedNUnitTest(node, TestFilter.Empty));
    }
}

The above reads NUnit tests in from the current assembly wraps them up and then adds them to our inhouse test harness. I haven't included these classes but they're not really important to understanding how the NUnit code works.

The really useful bit of information here is the static to "InitialiseService" this took quite a bit of figuring out but is necessary to get the basic set of test readers loaded in NUnit. You need to be a bit careful when looking at the tests in NUnit aswell as it includes failing tests (which I assume dont work because of the number of statics involved) - so what looks like useful documentation is actually misleading.

Aside from that you can then run the tests by implementing EventListener. I was interested in getting a one to one mapping between our tests and NUnit tests so each test is run on it's own. To achieve this you just need to implement TestStarted and TestFinished to do logging:

    public void TestStarted(TestName testName)
    {

    }
    public void TestFinished(TestResult result)
    {
        string text;
        if (result.IsFailure) 
            text = "Failure";
        else if (result.IsError)
            text = "Error";
        else
            return;

        using (var block = CreateLogBlock(text))
        {
            LogFailureTo(block);
            block.LogString(result.Message);
        }
    }

There are a couple of problems with this approach: Inherited Test base classes from other assemblies with SetUp methods that delegate to ones in the current assembly dont get called. It also has problems with TestFixtureSetup methods which are only called in NUnit when TestSuites are Run (as opposed to running test methods on their own).

These both seem to be problems with NUnit although if you dont want to construct wrapped tests individually I think you could just put in a call to suite.Run with the appropriate parameters and this will fix the latter problem