[tox] Use posargs for the tests

This allows to run specific tests, and not all the tests in one go.
This is especially useful if you're writing a plugin or creating a test
for a specific scenario. Below an example of what would be possible

```
sudo tox -e stagetwo_tests -- tests/report_tests/plugin_tests/openstack/openstack.py
```

This will run stagetwo tests for the specific test, i.e. openstack in
this case

This also fixes the stagetwo tests, so that it picks up the systemd
python libs from the distro environment

Update the installation of avocado-framework from one place, so that we
don't need to change the version in many places. Adding
`test-requirements.txt` to handle this and integrate this with both tox
and Cirrus CI

Signed-off-by: Arif Ali <arif.ali@canonical.com>

.cirrus.yml

@@ -148,7 +148,7 @@ deb_build_task:
         apt -y install devscripts equivs python3-pip
         mk-build-deps
         apt -y install ./sosreport-build-deps*.deb
-        pip3 install "avocado-framework<104.0" --break-system-packages
+        pip3 install -r test-requirements.txt --break-system-packages
     main_script: |
         dpkg-buildpackage -b -us -uc -rfakeroot -m --build-by="noreply@canonical.com"
     prep_artifacts_script: mv ../*.deb ./sos_cirrus.deb
@@ -240,7 +240,7 @@ report_stageone_task:
         fi
         PIP_EXTRA=""
         [[ $(pip3 install --help | grep break-system) ]] && PIP_EXTRA="--break-system-packages"
-        pip3 install "avocado-framework<104.0" ${PIP_EXTRA}
+        pip3 install -r test-requirements.txt ${PIP_EXTRA}
     # run the unittests separately as they require a different PYTHONPATH in
     # order for the imports to work properly under avocado
     unittest_script: &unit_test |

test-requirements.txt

@@ -0,0 +1 @@
+avocado-framework<104.0

tox.ini

@@ -4,7 +4,7 @@ envlist = flake8
 [testenv]
 deps =
     -r{toxinidir}/requirements.txt
-    avocado-framework<104.0
+    -r{toxinidir}/test-requirements.txt
     python_magic
 setenv =
     PYTHONPATH = {toxinidir}/tests
@@ -15,6 +15,8 @@ stage_tests =
     tests/collect_tests \
     tests/report_tests \
     tests/vendor_tests
+foreman_tests =
+    tests/product_tests/foreman
 
 [testenv:flake8]
 deps = flake8
@@ -29,22 +31,23 @@ basepython = python3
 setenv =
     PYTHONPATH = .
 commands =
-    avocado run tests/unittests/
+    avocado run tests/unittests
 
 [testenv:stageone_tests]
 basepython = python3
 commands =
-    {[testenv]avocado_cmd} -t stageone {[testenv]stage_tests}
+    {[testenv]avocado_cmd} -t stageone {posargs:[testenv]stage_tests}
 
 [testenv:stagetwo_tests]
 basepython = python3
+sitepackages = True
 commands =
-    {[testenv]avocado_cmd} -t stagetwo {[testenv]stage_tests}
+    {[testenv]avocado_cmd} -t stagetwo {posargs:[testenv]stage_tests}
 
 [testenv:foreman_tests]
 basepython = python3
 commands =
-    {[testenv]avocado_cmd} -t foreman tests/product_tests/foreman/
+    {[testenv]avocado_cmd} -t foreman {posargs:[testenv]foreman_tests}
 
 [testenv:nosetests]
 basepython = python3