The loadscope setting is required for parallel execution of our system
tests using pytest. The option ensure that all tests within a single
(module) scope will be assigned to the same worker.
This is neccessary because the worker sets up the nameservers for all
the tests within a module scope. If tests from the same module would be
assigned to different workers, then the setup could happen multiple
times, causing a race condition. This happens because each module uses
deterministic port numbers for the nameservers.
In order to run the shell system tests, the pytest runner has to pick
them up somehow. Adding an extra python file with a single function
for the shell tests for each system test proved to be the most
compatible way of running the shell tests across older pytest/xdist
versions.
Modify the legacy run.sh script to ignore these pytest-runner specific
glue files when executing tests written in pytest.
Special care needs to be taken to support older pytest / xdist versions.
The target versions are what is available in EL8, since that seems to
have the oldest versions that can be reasonably supported.
When an issue occurs inside a fixture (e.g. servers fail to start/stop),
the test result won't be detected as failed, but rather an error will be
thrown.
To ensure the tempdir is kept even if the test itself passes but the
system_test() fixture throws an error, a different mechanism is needed.
At the start of the critical test setup section, note that the fixture
hasn't finished yet. When this is detected in the system_test_dir()
fixture, it is recognized as error in test setup/teardown and the temp
directory is kept.
This may seem cumbersome, because it is. It's basically a workaround for
the way pytest handles fixtures and test errors in general.
The temporary directory contains artifacts for the pytest module. That
module may contain multiple individual tests which were executed
sequentially. The artifacts should be kept if even one of these tests
failed.
Since pytest doesn't have any facility to expose test results to
fixtures, customize the pytest_runtest_makereport() hook to enable that.
It stores the test results into a session scope variable which is
available in all fixtures.
When deciding whether to remove the temporary directory, find the
relevant test results for this module and don't remove the tmpdir if any
one the tests failed.
For every pytest module, create a copy of its system test directory and
run the test from that directory. This makes it easier to clean up
afterwards and makes it less error-prone when re-running (failed) tests.
Configure the logger to capture the module's log output into a separate
file available from the temporary directory. This is quite convenient
for exploring failures.
Cases where temporary directory should be kept are handled in a
follow-up commits.
This is basically the pytest re-implementation of the run.sh script.
The fixture is applied to every module and ensures complete test
setup/teardown, such as starting/stopping servers, detecting coredumps
etc.
Note that the fixture system_test_dir is not defined yet. It is omitted
now for review readability and it's added in follow-up commits.
Add fixtures for deriving system test name from the directory name and
for a module-specific logger.
Add fixtures to execute shell and perl scripts. Similar to how run.sh
calls commands, this functionality is also needed in pytest. The
fixtures take care of switching to a proper directory, logging
everything and handling errors.
Note that the fixture system_test_dir is not defined yet. It is omitted
now for review readability and it's added in follow-up commits.
This is basically a pytest re-implementation of the get_ports.sh script.
The main difference is that ports are assigned on a module basis, rather
than a directory basis. Module is the new atomic unit for parallel
execution, therefore it needs to have unique ports to avoid collisions.
Each module gets its ports through the env fixture which is updated with
ports and other module-specific variables.
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.
The commands executed by pytest during a system test need to have the
same environment variables set as if they were executed by the run.sh
shell script.
It was decided that for the moment, legacy way of executing system tests
with run.sh should be kept, which complicates things a bit. In order to
avoid duplicating the required variables in both conf.sh and pytest, it
was decided to use the existing conf.sh as the only authoritative
place for the variables.
It is necessary to process the environment variables from conf.sh right
when conftest.py is loaded, since they might be needed right away (e.g.
to test for feature support during test collection).
This solution is a bit hacky and is only meant to be used during the
transitory phase when both pytest and the legacy run.sh are both
supported. In the future, a superior pytest-only solution should be
used.
For discussion of other options, refer to
https://gitlab.isc.org/isc-projects/bind9/-/merge_requests/6809#note_318889
The legacy system test framework uses pytest to execute some tests.
Since it'd be quite difficult to convince pytest to decide whether to
include conftest.py (or which ones to include when launching from
subdir), it makes more sense to have a shared conftest.py which is used
by both the legacy test runner invocations of pytest and the new pytest
system test runner. It is ugly, but once we drop support for the legacy
runner, we'll get rid of it.
Properly scope the *port fixtures in order to ensure they'll work as
expected with the new pytest runner. Instead of using "session" (which
means the fixture is only evaluated once for the entire execution of
pytest), use "module" scope, which is evaluated separately for each
module. The legacy runner invoked pytest for each system test
separately, while the new pytest runner is invoked once for all system
tests -- therefore it requires the more fine-grained "module" scope to
for the fixtures to work properly.
Remove python shebang, as conftest.py isn't supposed to be an executable
script.
Most Python-based system tests need to know which ports were assigned to
a given test by bin/tests/system/get_ports.sh. This is currently
handled by inspecting the values of various environment variables (set
by bin/tests/system/run.sh) and passing the port numbers to Python
scripts via pytest fixtures. However, this glue code has so far been
copy-pasted into each system test using it, rather than reused.
Since pytest also looks for conftest.py files in parent directories,
move commonly used fixtures to bin/tests/system/conftest.py. Set the
scope of all the moved fixtures to "session" as their return values are
only based on environment variables, so there is no point in recreating
them for every test requesting them. Adjust test code accordingly.
