Getting Started with xUnit pt. 2

Test Fixture Setup and Tear Down

In the last xUnit post we covered how xUnit handles setup and tear down of tests by using the constructor for setup and implementing IDisposable for tear down instead of the usual attributes. That's great but since xUnit instantiates an instance of the test class for each test, what if your tests require some common setup that you'd rather not have happen for every single test.

Again no attributes for test fixture setup or test fixture tear down. Instead you create a separate class to contain the required actions. Then you have the class containing your tests inherit IClassFixture where T is the class containing the fixture setup. xUnit will then recognize that the class needs to be instantiated before the tests are run. If you need to access members or methods inside the setup class you then need to have your test class contain a constructor with that type as a parameter and xUnit will inject it for you.

public class FixtureState:IDisposable
{

public void FixtureState()
{
//Fixture Setup Here 
}

public void Dispose()
{

//Fixture Tear Down Here
}


}

public class Tests:IClassFixture<FixtureState>
{

private FixtureState _fixture;

//if you want access to members of the shared fixture FixtureState
public Tests(FixtureState theState)
{
  _fixture=theState;
}

//tests

}

I'm not sure exactly how I feel about this arrangement. I felt like using the constructor for setup and and IDisposable for tear down made logical sense. This however seems like it might start to convolute your test classes. It may seem like a heavy solution to some, since a whole separate class has to wired up and injected. Part of me says that it makes sense to start separating the concerns like this. Looking at the code though it feels a little harder to consume for newcomers.

Built In Data Driven Options

Internal Sources

There are three different attributes to start with when using data driven tests where the data provided will be code based. MemberData and PropertyData attributes accept a name of a static member or property that needs to return an IEnumerable<object[]> where the object array contents match the method signature of your test. There is also ClassData which accepts a type name of a class which is enumerable that xUnit will instantiate and use to supply values to your tests.

External Sources

xUnit offers some nice options for utilizing external data to drive you tests. They follow the same convention as the internal sources of being *Data, however you won't find them documented on the xUnit site. Technically I believe they are part of the xUnit extensions project (although it's the same github repo). Inside the samples folder you will find an ExcelData example. There are also SqlServerData and OleDbData options. Inside the attribute you specify a data source and query for locating the appropriate data. These seem like they add some nice functionality that I haven't seen combined with a unit test framework.

Final Thoughts

I really want to like xUnit but it seems to fight you from finding more about it. I've had to scour the internet to find examples and all I can find are bits and pieces which may or may not be up to date. From what I can tell, you need to start reading through the source code to find answers, since their site only really has a getting started guide.

Examples to follow

Since I couldn't find much in the way of documentation, I will be putting together some more detailed examples. So stay tuned and I'll update the post with a link to them on github.