Access NUnit Test Name within TestCaseSource

Question

The property TestName has a support in NUnit 3 for string formatting.

Here's an example usage:

private static IEnumerable TestData()
{
    TestCaseData data;

    data = new TestCaseData(new Foo("aaa"))
                            .SetName("case 1 {m}");
    yield return data;

    data = new TestCaseData(new Foo("bbb"));
    yield return data;
}

Will generate the following out put:

As you can see the test names the of the first case contains the custom prefix + the method name.

Use this link for more information about NUnit's string formating capability.

2 classes are resposable for this action NUnitTestCaseBuilder (line 83) and TestNameGenerator method .GetDisplayName().

This isn't a perfect answer, but the best solution I've found so far is that I create a wrapper for the TestData emitter that gets passed in as the TestCaseSource.

[Test, TestCaseSource("TestData_Test1")] 
public void Test1(Foo foo)
{
    // test 1
}

[Test, TestCaseSource("TestData_Test2")] 
public void Test2(Foo foo)
{
    // test 2
}


private static IEnumerable TestData_Test1() 
{
   return TestData_Base("Test1"); 
} 

private static IEnumerable TestData_Test2() 
{
   return TestData_Base("Test2"); 
} 

private static IEnumerable TestData_Base(string testName) 
{
   TestCaseData data; 

   data = new TestCaseData(new Foo("aaa"));
   data.SetName(string.Format("{0}(Foo=aaa)", testName)); 
   yield return data; 

   data = new TestCaseData(new Foo("bbb"));
   data.SetName(string.Format("{0}(Foo=bbb)", testName)); 
   yield return data; 
}

This means that my tests are now emitted from NCrunch, TeamCity, etc as

Test1(Foo=aaa)
Test1(Foo=bbb)
Test2(Foo=aaa)
Test2(Foo=bbb) 

Which is at least better than the completely useless default.

Well, if you are lucky to use .NET 4.5, you can use the [CallerMemberName] attribute on the last argument of the constructor of a new TestCaseSourceEx attribute extending TestCaseSource, which will give you the test method name inside the attribute constructor.

Here's a working sample:

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
public class TestCaseSourceEx : TestCaseSourceAttribute
{
    public TestCaseSourceEx(Type sourceType, string sourceName, [CallerMemberName] string methodName = null)
        : base(sourceType, sourceName)
    {

    }
    public TestCaseSourceEx(string sourceName, [CallerMemberName] string methodName = null)
        : base(sourceName)
    {

    }
}

[TestFixture]
public class SampleTests
{
    public IEnumerable List = new[] { new string[] { "test-username", "test-password" } };

    [Test, TestCaseSourceEx("List")]
    public void SampleTests_LoginTest(string username, string password)
    {

    }
}

After long googling i've found my solution which was alot easier than those posted above:

1st. In test case I've added another parameter: string testName:

[Test, TestCaseSource("TestData")] 
public void Test1(string testName, Foo foo)
{
    // test 1
}

[Test, TestCaseSource("TestData")] 
public void Test2(String testName, Foo foo)
{
    // test 2
}

2nd. in TestCaseData I've added another parameter which shows unique property of Foo object eg. name

private static IEnumerable TestData() 
{
   TestCaseData data; 

   Foo data1 = new Foo("aaa");
   data = new TestCaseData(data1.name, data1);
   yield return data; 

   Foo data2 = new Foo("bbb");
   data = new TestCaseData(data2.name, data2);
   yield return data; 
}

In NUnit runner the result are displayed like this:

Namespace.That.Is.Very.Long.TestClass.Test1("aaa", Namespace.That.Is.Very.Long.Foo)
Namespace.That.Is.Very.Long.TestClass.Test1("bbb", Namespace.That.Is.Very.Long.Foo)  

This makes tests separate in output window, while i'm still able to see exactly which test is being runned.