On Thu, Sep 30, 2021 at 3:21 PM 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
Reviewed-by: Brendan Higgins brendanhiggins@google.com