.gitlab-ci.yml: DO NOT MERGE - Install tox and try it in CI

.gitlab-ci.yml

@@ -13,7 +13,7 @@ stages:
 variables:
   PYTEST_ADDOPTS: "--color=yes"
   INTEGRATION_CACHE: "${CI_PROJECT_DIR}/cache/integration-cache"
-  TEST_COMMAND: 'python3 setup.py test --index-url invalid://uri --addopts --integration'
+  TEST_COMMAND: 'tox -- --integration'
 
 #####################################################
 #                  Prepare stage                    #
@@ -72,6 +72,10 @@ source_dist:
   - cd dist && ./unpack.sh
   - cd buildstream
 
+  # Install tox
+  - pip3 install tox
+  - pip3 install tox-venv
+
   script:
   - useradd -Um buildstream
   - chown -R buildstream:buildstream .
@@ -134,6 +138,10 @@ tests-unix:
     - dnf mark install fuse-libs
     - dnf erase -y bubblewrap ostree
 
+    # Install tox
+    - pip3 install tox
+    - pip3 install tox-venv
+
     # Since the unix platform is required to run as root, no user change required
     - ${TEST_COMMAND}