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.