Testing against the (Garbage Collection) Clock, or, Don't create your Test Cases as anonymous classes
I wrote a while ago about how I’d started creating my test cases as anonymous classes.
I continued this practice until I was slapped in the face by my own stoopidity yesterday. We were seeing a problem where tests were failing individually but appearing to run fine in rake.
James was looking into it…
James: it seems like the ones defined by Class.new(Test::Unit::TestCase) aren't always being found in the ObjectSpace James: but I can't quite work out why James: i'm tempted to name them all as defined classes Chris: oh ok Chris: go for it James: i'm pretty sure that works ok Chris: interesting James: only difference i can think of is that if the file is loaded twice you will create two instances of the anonymous class James: whereas with the named class it will just reopen same class Chris: why would that be a problem? James: but it doens't look like its being loaded twice anyway James: dunno James: its the only difference i can think of, but it doesn't explain anything James: can you think of any other differences Chris: so if you create named classes for the testcases in p_l_i_test does it then fail in rake? James: yup - and i've seen the problem in other tests where anonymous tests are defined James: so there are quite a few tests that haven't been running in rake Chris: bugger Chris: i think ben just explained the problem James: yeah? Chris: as the classes aren't assigned to constants they can be garbage collected Chris: oops James: aha Chris: no more anonymous test classes for christopher James: that explains - why they were in the ObjectSpace one minute and not the next
Note that p_l_i_test mentioned above is just a shorthand for one of our tests that was failing individually but ‘running’ (or as we now know, not running) from rake.
So, although you get a little added excitement to your testing (“Will this test class run before it gets garbage collected???”), it’s probably a lot safer to not use anonymous classes when testing.
James has just informed me that we gained about 230 tests in rake by naming all of our test cases…
