Richard Slade

Embarking on a new project I decided that it would be a much better idea this time to separate the nunit test cases into separate projects from the production assemblies. I had read the recent article in VSJ magazine and was ready put into practice those things that I wasn't routinely doing (I.e. separating my test cases from my production class libraries.

So, the first thing that I wanted to do was write some quick scratch code in order to make sure that everything would work. My scratch code doesn't always tend to be quick as I want to make sure that it works under as many scenarios as possible. Firstly, I made a class library called CompanyName.ExampleProject.dll, wrote a class in the class library, and of course a couple of methods in the class to be able to test. Let's say then we had:

CompanyName.ExampleProject.MyClass that contained:

public string SayHello() method.

All fine so far. Then, being that I like to make sure that everything is set up in the normal fashion, i altered the AssemblyInfo file, adding in all the usual bits like AssemblyTitle, AssemblyCopyright and AssemblyCulture.

Great, I'm all set-up. Now to try and write another project to test it.

So, I set-up another project called CompanyName.TestExampleProject.dll. In a class in this library, I added an nunit test to test the CompanyName.ExampleProject.MyClass class. All looked fine, very little code to test. Run the test.

CompanyName.TestExampleProject.Tests.TestMyClass : System.IO.FileNotFoundException : File or assembly name CompanyName.ExampleProject, or one of its dependencies, was not found.

How odd. Everything compiled correctly and i could even instantiate the SayHello() method from a separate web project, so there was certainly nothing missing.

I verified that everything was in the proper place and that the code was as simple as possible. However, the only thing that I needed to do to make the test pass was to remove any reference to MyClass.

Even if I simply made a fake test and added a line: MyClass c1 = new MyClass then nunit would return the same error message.

Ok, so what would happen if I added the test into the same assembly as the MyClass class? Yep, just as in other projects, now everything would pass. So i could now make my test pass or fail,simply by moving it into another assembly. This shouldn't happen.

Looked at the more specific error message generated by nunit.

at System.Reflection.RuntimeConstructorInfo.InternalInvoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean isBinderDefault)

at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

at NUnit.Core.Reflect.Construct(Type type) at NUnit.Core.TestFixture.DoSetUp(TestResult suiteResult)

After more testing, i found the answer. i had added an AssemblyCulture to the main project assembly. Yes, this is a good thing to do. The culture I had added was perfectly legal (en-GB). With the test in the test project (CompanyName.TestExampleProject.dll), if I changed the AssemblyCulture in the other assembly (CompanyName.ExampleProject.dll) to something illegal (E.g. hello) then nunit would tell me straight away that the culture info is not valid. That's good. However, if I changed it to a legal culture, then nunit would not complain until I tried to run the tests.

conclusion
It's my conclusion that this is a bug in nunit. In order to separate my nunit tests into a separate project I need to remove the AssemblyCulture information from the assembly that is being tested. Hardly ideal, but worth it to be able to separate the tests from the production code.

Cheers

R