Unit Testing without Assertions

Question

Occasionally I come accross a unit test that doesn\'t Assert anything. The particular example I came across this morning was testing that a log file got written to when a co

Answer 1

Such a test smells. It should check that the file was written to, at least that the modified time was updated perhaps.

I've seen quite a few tests written this way that ended up not testing anything at all i.e. the code didn't work, but it didn't blow up either.

If you have some explicit requirement that the code under test doesn't throw an exception and you want to explicitly call out this fact (tests as requirements docs) then I would do something like this:

try
{
  unitUnderTest.DoWork()
}
catch
{
  Assert.Fail("code should never throw exceptions but failed with ...")
}

... but this still smells a bit to me, probably because it's trying to prove a negative.