Some system tests require extra programs and/or dependencies to be
compiled first. This is done via `make check` with the automake
framework when using check_* variables such as check_PROGRAMS.
To avoid running any tests via the automake framework, set the TESTS
env variable to empty string and utilize `make -e check` to override
default Makefile variables with environment ones. This ensures automake
will only compile the needed dependencies without running any tests.
Additional consideration needs to be taken for xdist. The compilation
command should be called just once before any tests are executed. To
achieve that, use the pytest_configure() hook and check that the
PYTEST_XDIST_WORKER env variable isn't set -- if it is, it indicates
we're in the spawned xdist worker and the compilation was already done
by the main pytest process that spawned the workers.
This is mostly done to have on-par functionality with legacy test
framework. In the future, we should get rid of the need to run "empty"
make -e check and perhaps compile test-stuff by default.
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