Being Cellfish

Stuff I wished I've found in some blog (and sometimes did)

2008 Advent Calendar December 5th

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2008 Advent Calendar December 5th

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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.

  • 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?



  • 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 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... :-)

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