Re: [PATCH v4 4/4] kunit: tool: support running each suite/test separately

[Brendan Higgins <brendanhiggins@google.com>]

On Thu, Sep 30, 2021 at 4:05 PM David Gow <davidgow@google.com> wrote:
>
> On Fri, Oct 1, 2021 at 6:21 AM Daniel Latypov <dlatypov@google.com> wrote:
> >
> > The new --run_isolated flag makes the tool boot the kernel once per
> > suite or test, preventing leftover state from one suite to impact the
> > other. This can be useful as a starting point to debugging test
> > hermeticity issues.
> >
> > Note: it takes a lot longer, so people should not use it normally.
> >
> > Consider the following very simplified example:
> >
> >   bool disable_something_for_test = false;
> >   void function_being_tested() {
> >     ...
> >     if (disable_something_for_test) return;
> >     ...
> >   }
> >
> >   static void test_before(struct kunit *test)
> >   {
> >     disable_something_for_test = true;
> >     function_being_tested();
> >     /* oops, we forgot to reset it back to false */
> >   }
> >
> >   static void test_after(struct kunit *test)
> >   {
> >     /* oops, now "fixing" test_before can cause test_after to fail! */
> >     function_being_tested();
> >   }
> >
> > Presented like this, the issues are obvious, but it gets a lot more
> > complicated to track down as the amount of test setup and helper
> > functions increases.
> >
> > Another use case is memory corruption. It might not be surfaced as a
> > failure/crash in the test case or suite that caused it. I've noticed in
> > kunit's own unit tests, the 3rd suite after might be the one to finally
> > crash after an out-of-bounds write, for example.
> >
> > Example usage:
> >
> > Per suite:
> > $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit --run_isolated=suite
> > ...
> > Starting KUnit Kernel (1/7)...
> > ============================================================
> > ======== [PASSED] kunit_executor_test ========
> > ....
> > Testing complete. 5 tests run. 0 failed. 0 crashed. 0 skipped.
> > Starting KUnit Kernel (2/7)...
> > ============================================================
> > ======== [PASSED] kunit-try-catch-test ========
> > ...
> >
> > Per test:
> > $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit --run_isolated=test
> > Starting KUnit Kernel (1/23)...
> > ============================================================
> > ======== [PASSED] kunit_executor_test ========
> > [PASSED] parse_filter_test
> > ============================================================
> > Testing complete. 1 tests run. 0 failed. 0 crashed. 0 skipped.
> > Starting KUnit Kernel (2/23)...
> > ============================================================
> > ======== [PASSED] kunit_executor_test ========
> > [PASSED] filter_subsuite_test
> > ...
> >
> > It works with filters as well:
> > $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit --run_isolated=suite example
> > ...
> > Starting KUnit Kernel (1/1)...
> > ============================================================
> > ======== [PASSED] example ========
> > ...
> >
> > It also handles test filters, '*.*skip*' runs these 3 tests:
> >   kunit_status.kunit_status_mark_skipped_test
> >   example.example_skip_test
> >   example.example_mark_skipped_test
> >
> > Signed-off-by: Daniel Latypov <dlatypov@google.com>
> > Reviewed-by: David Gow <davidgow@google.com>
> > ---
>
> Thanks -- this version works for me.
>
> I think the requirement that test and suite names contain neither full
> stops nor spaces is a reasonable one. There aren't any current tests
> which would break it, as far as I know.

I agree. Is this currently codified in the test naming conventions document?