2008 Advent Calendar December 5th

 

   1:      public class Advent5 : IDisposable
   2:      {
   3:          private IFileUtil m_file;
   4:   
   5:          public void Dispose()
   6:          {
   7:              m_file.Delete();
   8:          }
   9:   
  10:          [Fact]
  11:          public void TestReadOK()
  12:          {
  13:              // Create a test file
  14:              m_file = new FileUtil("SomeFile.txt");
  15:              m_file.Create("CONTENT");
  16:   
  17:              // Should be able to read file
  18:              Assert.DoesNotThrow(() => { m_file.Read(); });
  19:          }
  20:   
  21:          [Fact]
  22:          public void TestReadFails()
  23:          {
  24:              // Create a test file
  25:              m_file = new FileUtil("SomeFile.txt");
  26:              m_file.Create("CONTENT");
  27:   
  28:              m_file.Readable = false;
  29:   
  30:              // Should NOT be able to read file.
  31:              Assert.Throws<AccessViolationException>(() => { m_file.Read(); });
  32:          }
  33:      }

Now we're using Xunit-net's clean up mechanism, the IDisposableinterface. We still got some redundant code in the setup part of each test. Next I'll refactor that.

Comments

• Anonymous
  December 05, 2008
  Hmm. Would it not be better to implement IDisposable on your tests, rather than use a destructor (finalizer)? Using the destructor, your tear down code will get called non-deterministically, some time after a garbage collection, and I'm assuming xUnit doesn't force a GC between test runs. So, theoretically, your file might not get deleted if the runner exits before a GC. Or, more relevantly, the file might not (probably won't?) get deleted between two tests, causing unexpected side effects. If you use IDisposable, I would expect xUnit to explicitly clean up the class before moving onto the next test. Does this sound about right? Cheers Matt

• Anonymous
  December 06, 2008
  Yes you are more than correct. I had a brain malfunction writing these tests and was stuck in C++. And you got me before I had the chance to change things... Obviously the finalizer/destructor is wrong. IDisposable is the right way and xUnit.net makes sure Dispose is called between each test. It is not an excuse but an explanaition, I was in a hurry when I wrote this in the wrong way and working mainly in C++ i messed up... But from now on the tests will be (more) correct... Nice to see that someone is actually reading these tests... :-)