thanks for helping, I get this error

make: *** No rule to make target `/tmp/riot/build', needed by `..in-docker-container'.  Stop.

also I'm not sure about adding the test because its scope and purpose is very different, i.e. checking the build/make system and not RIOT code. So maybe such should rather go into dist/tests, or so?

Mac make not handling the implicit rule :/ >< Can you try debugging why it is not using this rule ?

https://github.com/smlng/RIOT/pull/6/files#diff-ebbb3165b3276a049759e5cb4e04d6a4R715

A solution could be to replace it with $(BUILD_DIR)/: %/: but then we will need to add all directories to this list (I plan to add $(BINDIR) there soon). So I would prefer to know if it is really needed.

The test was not 100% necessary, it was just to show that the new directory was lacking a proper docker integration. And if a mistake can be made like this, having a test verifying it still works is for me important.

There is already build system/BSP tests like tests/libc_newlib/ and tests/cortexm_common_ldscript/ but these must compile for a board.
So sure I could move it to dist/tests. I can do it after it is tested and works for you.

The build system is part of the riot distribution, if not, we coul remove it and the flash scripts and not bother. That's why I want to start adding non regressions tests.

Hmm just noticed than it is complaining about /tmp/riot/build instead of /tmp/riot/build/… so maybe there is something else.

Does this work ? (would explain things about MAKEOVERRIDES)

rm -rf /tmp/riot/build; \
BUILD_DIR=/tmp/riot/build BUILD_IN_DOCKER=1 DOCKER="sudo docker" make -C tests/build_system_builddir_docker clean all test

or this ? (with the directory with a slash but still on the command line)

rm -rf /tmp/riot/build; \
make -C tests/build_system_builddir_docker clean all test \
    BUILD_DIR=/tmp/riot/build/ \
    BUILD_IN_DOCKER=1 DOCKER='sudo docker'

@cladmi when I manually create the directory, i.e. mkdir -p /tmp/riot/build, before running the build in docker command it works - though there also is a problem with the /etc/localtime on macOS, but that's a different story. So it seems that it does not create the BUILD_DIR first, or at least is not able to.

Yep that is the reason.

If I comment the target with the mkdir in Makefile.include, I get

make: *** No rule to make target '/tmp/riot/build/', needed by '..in-docker-container'.  Stop

So build/ with a terminating /.

It looks like it is an issue with make 3.81 as explained at the end of this post http://ismail.badawi.io/blog/2017/03/28/automatic-directory-creation-in-make/

I will update my branch to test the fix he did.

If this works, I can do a single PR to discuss the directory creation rule.

To not wait for it, the other solution is to do the mkdir -p inside of the ..in-docker-container target as it was done for others already. I could update it later.

does work now on macOS (after rebasing on latest RIOT master). How to proceed here? You wanna squash yourself or should I merge and squash you commits in my branch?

I will do a PR on RIOT about directory creation.

Because the way I did it for the moment is also wrong.
It was only for testing on mac and for this specific case. When we will work with BINDIR it will not work.

A target should never directly depend on a directory as the directory modification date is the last created file inside. It should be done by using an order only dependency.

But as I tested before and re-verified, this does not work when doing make clean all -j with order-only targets (deleting and creating files at the same time is not supposed to mean anything so it's hard to make it handled).

For the time being I will replace with only doing a mkdir -p inside the target.

I replaced with creating the directory in the target. I also currently removed the test.
Before removing commits, I saved the branch to https://github.com/cladmi/RIOT/tree/pr/common/build_saved_with_tests

I re-ran the test from the previous branch and it is working.

You can merge/rebase in your branch if you want.