build system: race condition when building and running an app for native

[maribu]

Description

make BOARD=native -C tests/unittests all test -j

Seems to be racy: At least occasionally an old binary seems to be run. This is probably

Steps to reproduce the issue

Run make BOARD=native -C tests/unittests all test -j, it should pass. Add e.g. TEST_ASSERT_EQUAL_INT(1, 0); to one of the tests and run make BOARD=native -C tests/unittests all test -j. This time it should fail, but it will pass again. Run make BOARD=native -C tests/unittests all test -j again, this time it will fail as expected.

Expected results

make BOARD=native -C tests/unittests all test -j should build and run the test using the freshly build executable.

Actual results

At least occasionally, the old binary is run instead.

Versions

Current master.

[Enoch247]

Is this only true for the native board, or just only known to be true for native, and unproven/tests for other boards?

[maribu]

I have never observed this on other boards. But there is an explicit flash target needed. Probably tests does correctly depend on flash (if that is among the goals), and flash correctly depends on the linked binary. native is special in the regard that flash is a no-op.