How can I better the readability of inline test data?

Question

[TestCase(new[] { 1, 2 }, 1, Result = 2)]
[TestCase(new[] { 1, 2 }, 2, Result = 1)]
[TestCase(new[] { 1, 2, 3 }, 2, Result = 2)]
[TestCase(new[] { 1, 2, 3, 4 }, 2, Result = 2)]
[TestCase(new[] { 1, 2, 3, 4 }, 10, Result = 1)]
public int TotalPageCountIsAccurate(int[] testSequence, int pageSize)
{
 var pagedList = new PagedList<int>(testSequence, 0, pageSize);
 return pagedList.TotalPageCount;
}

I wrote this test about five minutes ago and I can barely understand it - I dread to think how hard it will be to read in a few weeks. How can I refactor the TestCase attribute to improve readability?

I thought about using named arguments or (maybe) introducing a some well-named fields, but neither of these ideas appear to be feasible.

• Jeroen Vannevel: What isn't feasible about using named arguments?
• User 12345678: The TestCase attribute's argument names are along the lines of Argument1, Argument2 etc. which is no more descriptive than not using named arguments.
• Jeroen Vannevel: Oh right. I don't think you can make it any clearer since this is pretty much how it is done. I find it quite readable myself but you can always add some documenttion to describe what the testcases do.

Answer 1

If I'm right you could do at least two things:

1. Generate the array and pass only the number of items to the test method.

2. Rename testSequence to something more descriptive, like items, elements etc.

[TestCase(2, 1, Result = 2)]
[TestCase(2, 2, Result = 1)]
[TestCase(3, 2, Result = 2)]
[TestCase(4, 2, Result = 2)]
[TestCase(4, 10, Result = 1)]
public int TotalPageCountIsAccurate(int itemCount, int pageSize)
{
 // generates the item array with itemCount items
 var items = Enumerable.Range(0, itemCount).ToArray();
 var pagedList = new PagedList<int>(items, 0, pageSize);
 return pagedList.TotalPageCount;
}

(I can't check whether is it valid C# or not but I hope you get the idea.)

I would also create a test with an empty array.

Answer 2

I would probably go with @palacsint's idea, but just to throw it out there you can also use a test case factory:

[TestFixture]
public class PagingTests
{
 [Test]
 [TestCaseSource(typeof(PagingTestCaseFactory), "TestCases")]
 public int TotalPageCountIsAccurate(int itemCount, int pageSize)
 {
 var items = Enumerable.Range(0, itemCount).ToArray();
 var pagedList = new PagedList<int>(items, 0, pageSize);
 return pagedList.TotalPageCount;
 }
}
public class PagingTestCaseFactory
{
 public static IEnumerable TestCases
 {
 get
 {
 yield return ItemCountEqualToPageSize(2, 2).Returns(1);
 yield return ItemCountGreaterThanPageSize(2, 1).Returns(2);
 yield return ItemCountGreaterThanPageSize(3, 2).Returns(2);
 yield return ItemCountGreaterThanPageSize(4, 2).Returns(2);
 yield return ItemCountLessThanPageSize(4, 10).Returns(1);
 }
 }
 private static TestCaseData ItemCountEqualToPageSize(int itemCount, int pageSize)
 {
 return new TestCaseData(itemCount, pageSize);
 }
 private static TestCaseData ItemCountGreaterThanPageSize(int itemCount, int pageSize)
 {
 return new TestCaseData(itemCount, pageSize);
 }
 private static TestCaseData ItemCountLessThanPageSize(int itemCount, int pageSize)
 {
 return new TestCaseData(itemCount, pageSize);
 }
}