def permute(tpl):
        """Gives the set of valid permutations for this tuple."""
        if len(tpl) == 0:
            yield ()
        else:
            for t in permute(tpl[1:]):
                for n in range(0, len(t) + 1):
                    yield t[0:n] + (tpl[0],) + t[n:]

    permute_test = tuple(permute((1, 2, 3, 4)))
    assert(len(permute_test) == 24)
    for i in range(0, 24):
        assert(len(permute_test[i]) == 4)

    for i in range(0, 23):
        for j in range(i + 1, 24):
            assert(permute_test[i] != permute_test[j])

    assert(sorted(permute((1, 2))) == [(1, 2), (2, 1)])

Use assertItemsEqual.

http://docs.python.org/library/unittest.html#unittest.TestCa...

The way I do it:

In the doctest, I include a few toy examples, stuff I can verify by hand, and which helps the user understand what I'm doing.

In the unit tests, I try to do things in the style of Haskell's Quickcheck (the greatest testing library out there). Generate some random values and test properties (e.g., len(permute(x)) == factorial(len(x))).

However, you might find the itertools library helpful, particularly itertools.permutations(): http://docs.python.org/library/itertools.html#itertools.perm...

Otherwise you have to do what I had to last month, which was go back—after the fact—and write unit tests for a large chunk of our code base because we didn't have an automated way of verifying that our logic worked with different (read: non-happy path) data sets.