The basic model is this:
 - a test can have a single outcome [yes, the api is ambiguous, but there it is]
 - subtests let you identify multiple variations of a single test (note the id tweak etc) and *may* be reported differently

We certainly must not report the test as a whole passing if any subtest did not pass.

Long term I want to remove the error/failure partitioning of exceptions; its not actually useful.

The summary for the test, when subtests are used, should probably enumerate the states.

test_foo (3 passed, 2 skipped, 1 failure)

in much the same way the run as a whole is enumerated.