L2SS-313: Resolve access to coverage as module

.gitignore

@@ -22,6 +22,7 @@ tangostationcontrol/dist
 tangostationcontrol/docs/build
 
 **/coverage.xml
+**/.coverage
 **/.ipynb_checkpoints
 **/pending_log_messages.db
 **/.eggs

tangostationcontrol/tox.ini

@@ -26,19 +26,31 @@ setenv = TESTS_DIR=./tangostationcontrol/integration_test
 commands =
     stestr run --serial {posargs}
 
+; The access to coverage as module is a bit of an ugly hack. This is due to
+; cover inheriting testenv which has `sitepackages = True`, meaning that global
+; packages can be accessed by the tox environment. Our tango images already have
+; coverage system wide installed, however, the system wide installation will
+; never look inside tox its virtualenv for packages. So accessing stestr and
+; others fail.. We can't remove `sitepackages = True` either as we need access
+; to tango and installing this package is non-trivial. The solution is to
+; prevent calling binaries directly and utilizing python to resolve the
+; requested module. In addition stestr does not natively support generating
+; coverage reports which is where the `PYTHON=python -m coverage run....` comes
+; from.
 [testenv:cover]
-allowlist_externals =
-    coverage
+setenv =
+    VIRTUAL_ENV={envdir}
+    PYTHON=python -m coverage run --source tangostationcontrol --parallel-mode
 deps =
     -r{toxinidir}/test-requirements.txt
     -r{toxinidir}/../docker-compose/lofar-device-base/lofar-requirements.txt
 commands =
-    coverage erase
-    stestr run {posargs}
-    coverage combine
-    coverage html -d cover
-    coverage xml -o coverage.xml
-    coverage report
+  python -m coverage erase
+  stestr run {posargs}
+  python -m coverage combine
+  python -m coverage html -d cover
+  python -m coverage xml -o coverage.xml
+  python -m coverage report
 
 ; TODO(Corne): Integrate Hacking to customize pep8 rules
 [testenv:pep8]