[lttng-dev] [lttng-tools] Removal of root_regression tests

[Jonathan Rajotte-Julien]

Hi Marcel,

----- Original Message -----
> From: "Marcel Hamer via lttng-dev" <lttng-dev at lists.lttng.org>
> To: "lttng-dev" <lttng-dev at lists.lttng.org>
> Sent: Monday, 13 June, 2022 07:49:39
> Subject: [lttng-dev] [lttng-tools] Removal of root_regression tests

> Hello,
> 
> Since version v2.12.9 of lttng-tools the root_regression file has been emptied
> to make the tests part of the 'make check' sequence instead.
> 
> We were always actively using that test file as part of our regression testing.
> In our case we are working in a cross-compilation environment, where the run.sh
> script was used on target for testing and as such not at compile time. It is not
> easy to run a make check sequence on a target.

I would suggest that you take a look at how OpenEmbedded does it with ptest AFAIK it match your requirements:

https://github.com/openembedded/openembedded-core/blob/c7e2901eacf3dcbd0c5bb91d2cc1d467b4a9aaf7/meta/recipes-kernel/lttng/lttng-tools_2.13.7.bb#L75

> 
> It is now also a bit unclear which tests actually require root access and which
> tests do not. I understood this was the reason the file was called
> 'root_regression'?

Yes when the tests suites primarily used `prove` via run.sh.

We have been slowly moving away from it for a good time and now mostly use the Automake test harness as much as possible.

The worse that will happen if you run a test that required root as a non-root user is that `skip` tap output will be emitted.

> 
> Some questions that get raised because of this:
> 
> - Is there now an alternative way to run regressions on target in case of a
>  cross-compilation environment?

AFAIU, this is out of scope of the lttng project. Still, I would recommend that you see how yocto/oe do it with ptest.

> - Would there be a possibility to fill the 'root_regression' file again and
>  possibly revert this change?

Feel free to do it out-of-tree. I doubt that we are the only project that WindRiver handles that uses
the automake test harness and that do not provide a easy way to run on-target for cross-compilation testing.

A quick grep with "isroot" should get you 95% there.

> - How are tests now identified that require root access?

All tests that require root access test for it at runtime

Something along:

regression/tools/streaming/test_high_throughput_limits:

 if [ "$(id -u)" == "0" ]; then
 	isroot=1
 else
	 isroot=0
 fi

 skip $isroot "Root access is needed to set bandwidth limits. Skipping all tests." $NUM_TESTS ||
 {
 ...
    Tests are done here.
 }

Cheers