Add pytest testsuite to Gitlab CI

Saves the coverage of both testsuites, to allow us to compare them (and make sure the nose-based testsuite hasn't had a regression for some reason)

.gitlab-ci.yml

@@ -61,6 +61,34 @@ stages:
     paths:
       - coverage.xml
 
+.unit-tests-pytest: &unit-tests-pytest
+  stage: test
+  before_script:
+    # Create user, we do not want to test as root
+    - adduser --disabled-login --gecos "" $PRIMARY_USER
+    # Activate coverage for subprocesses
+    - printf 'import coverage\ncoverage.process_startup()\n' > "/usr/local/lib/python${PYTHON_VERSION}/site-packages/sitecustomize.py"
+    # Give $PRIMARY_USER permission to create cgroups
+    - test/for_each_of_my_cgroups.sh chgrp $PRIMARY_USER
+    - test/for_each_of_my_cgroups.sh chmod g+w $PRIMARY_USER
+    # Install BenchExec with `dev` dependencies
+    - sudo -u $PRIMARY_USER pip install --user ".[dev]"
+    # Start lxcfs
+    - lxcfs /var/lib/lxcfs &
+  script:
+    - sudo -u $PRIMARY_USER
+        COVERAGE_PROCESS_START=.coveragerc
+        coverage run -m pytest
+  after_script:
+    - sudo -u $PRIMARY_USER coverage combine
+    - sudo -u $PRIMARY_USER coverage report
+    - sudo -u $PRIMARY_USER coverage xml -o coverage-pytest.xml
+  tags:
+    - privileged
+  artifacts:
+    paths:
+      - coverage-pytest.xml
+
 unit-tests:python-3.7:
   <<: *unit-tests
   variables: