Setup tox

- add tox configuration for coverage reporting

tox.ini

@@ -1,13 +1,34 @@
 [tox]
 env_list =
-    py310
+    clean,py39,py310,py311,report
 minversion = 4.6.4
 
+[coverage:paths]
+source =
+    gvacommon
+
+[coverage:report]
+omit =
+    gvacommon/tests/*
+
 [testenv]
 description = run the tests with pytest
 package = wheel
 wheel_build_env = .pkg
 deps =
     pytest>=6
+    pytest-cov
 commands =
-    pytest {tty:--color=yes} {posargs}
+    pytest --cov --cov-append --cov-report=term-missing {tty:--color=yes} {posargs}
+
+[testenv:report]
+deps = coverage
+skip_install = true
+commands =
+    coverage report -m
+    coverage html
+
+[testenv:clean]
+deps = coverage
+skip_install = true
+commands = coverage erase