[Cppunit-devel] TestRegistry... What use for it?

[Baptiste L. <gai...@fr...>]

    As you may know, I've done the CppUnit Windows Edition. Well, I discussed 
with Bastiaan who have recently taken up the administration of the project and 
we'll be working in integrating things. The windows support will come (this 
version of cppunit is supposed to be cross-platform!).

    When I told him about the TestRegistry bug fix. He told me "the best bug 
fix would be to kill it. I don't see the use of a static registry. JUnit hasn't 
one either anyway."

    Let's not args about the actual implementation, but about the use for it.

    First, here is how the "thing" works:
      1) the TestCase constructor automatically register the test case to the 
TestRegistry.
      2) before running all the test, you're supposed to retreive all the 
registred test using the getAllTests() method and pass them to the test runner.

    Point 1 is definitely a no no, here is why:
       In the traditionnal implementation of your static suite method():
         suite->addTest( new TestCaller<MyTestCase>( "testSomething", 
testSomething ) );

       The problem ? TestCaller creates a new instance of MyTestCase. So what 
happens: the new instance is registered, and the TestCaller, being itself a 
TestCase is also registered!!! You get two tests registered when only one was 
supposed to be! Even worth, in the example, the test case are static variables, 
and guess what happen when the TestRegistry try to delete them !!!
       Conclusion: exterminates the "automatic registration", or at least 
remove it from TestCase and pull it down (I really don't see any use of an 
automatic registration of that form).

    Point 2:
       That's one is actually a nice thing, setting up your test runner look 
like this:
  TestRunner runner;
  TestRegistry registry = TestRegistry::getRegistry()
  runner.addTests( registry.getAllTests() );
  runner.run();

       You do the code once and don't need to update it. The only requierement 
is that you have your tests correctly registered. Of course that is the hard 
part. But suppose it works, it would be rather useful (who never forget to add 
a test either to a suite or to the test runner ?)
       
       The problem is that the registered test would be simple TestCaller, no 
possibility to say run suite XYZ (which would be matching the part your 
refactoring). Well, who said the registered test needed to be TestCaller, you 
can register suite. If only the top level suites would be registered, then 
everything would work fine. How to do that ? I don't know yet, but I'm playing 
with some stuff. I've already implemented a way to have suite for each unit 
test class registered (which is enough for my need at the current time), and I 
will try to extend the idea to build a real hieararchy.

    So my conclusion would be to leave it alone, it may be of use for some, but 
don't make it mandatory. It is a non core "feature" and should not be mandatory.

    Until next time, for the suite auto-registration...
    Baptiste.
     
---
Baptiste Lepilleur <gai...@fr...>
http://gaiacrtn.free.fr/index.html
Language: English, French