Update contrib ce-oem tox config

- Point to the correct version of Python using {envpython}
- Remove the "develop installation" step for the ce-oem provider
- Convert the test step into a test coverage one to generate an XML
report to be used later by Codecov

contrib/checkbox-provider-ce-oem/tox.ini

@@ -6,22 +6,23 @@ skipsdist=True
 [testenv]
 allowlist_externals = rm
 commands =
-    pip -q install ../../checkbox-ng
+    {envpython} -m pip -q install ../../checkbox-ng
     # Required because this provider depends on checkbox-support parsers & scripts
-    pip -q install ../../checkbox-support
+    {envpython} -m pip -q install ../../checkbox-support
     rm -f /var/tmp/checkbox-providers-develop/checkbox-provider-resource.provider
     rm -f /var/tmp/checkbox-providers-develop/checkbox-provider-base.provider
     rm -f /var/tmp/checkbox-providers-develop/checkbox-provider-certification-client.provider
     rm -f /var/tmp/checkbox-providers-develop/checkbox-provider-certification-server.provider
     rm -f /var/tmp/checkbox-providers-develop/checkbox-provider-ce-oem.provider
     # Install all providers in develop mode to make sure everything works fine
-    {envbindir}/python3 ../resource/manage.py develop
-    {envbindir}/python3 ../base/manage.py develop
-    {envbindir}/python3 ../certification-client/manage.py develop
-    {envbindir}/python3 ../certification-server/manage.py develop
-    {envbindir}/python3 manage.py develop
-    {envbindir}/python3 manage.py validate
-    {envbindir}/python3 manage.py test
+    {envpython} ../resource/manage.py develop
+    {envpython} ../base/manage.py develop
+    {envpython} ../certification-client/manage.py develop
+    {envpython} ../certification-server/manage.py develop
+    {envpython} manage.py validate
+    {envpython} -m coverage run manage.py test
+    {envpython} -m coverage report
+    {envpython} -m coverage xml
 
 [testenv:py3.5]
 deps =