The _do_discovery() method of unittest.TestProgram:

    def _do_discovery(self, argv, Loader=loader.TestLoader):

(from http://hg.python.org/cpython/file/2cf89e2e6247/Lib/unittest/main.py#l222 )

should be using self.testLoader instead of loader.TestLoader.  It's not consistent for some parts of TestProgram to use loader.TestLoader and other parts to use the testLoader passed in via the constructor.

I think you're correct - although I wonder if *anyone*, *ever* will be helped by the change. :-)

I will at least! :)  I noticed the issue after trying to use unittest test discovery with a custom loader.  Fortunately, there is at least this work-around (though it relies on an implementation detail):

    class MyTestProgram(unittest.TestProgram):

        # Override because of issue #17052.
        def _do_discovery(self, argv, Loader=None):
            if Loader is None:
                Loader = lambda: self.testLoader
            super(TestPizza, self)._do_discovery(argv, Loader=Loader)

New changeset b53b029895df by Michael Foord in branch 'default':
Merge. Closes issue 17052.
http://hg.python.org/cpython/rev/b53b029895df

Michael, was this implemented correctly?  Loader should be a callable (e.g. a class), but self.testLoader is an instance (it defaults to loader.defaultTestLoader, which equals loader.TestLoader()):

http://hg.python.org/cpython/file/b53b029895df/Lib/unittest/loader.py#l302

+- Issue #17502: unittest discovery should use self.testLoader.

Also, this should read Issue #17052.

I think you're right! Thanks.

New changeset ece0a2e6b08e by Michael Foord in branch '2.7':
Correction to issue 17052 fix
http://hg.python.org/cpython/rev/ece0a2e6b08e

New changeset 867763eb6985 by Michael Foord in branch '3.2':
Correction to issue 17052 fix
http://hg.python.org/cpython/rev/867763eb6985

New changeset a79650aacb43 by Michael Foord in branch 'default':
Merge. Closes issue 17052.
http://hg.python.org/cpython/rev/a79650aacb43

Thanks a lot for taking care of this issue, Michael.