Collect coverage information

setup.cfg

@@ -54,10 +54,30 @@ python =
     3.9: py39
 
 [testenv]
+setenv =
+    COVERAGE=1
+
 deps =
     pytest
     pytest-xdist
     cocotb-test
+    coverage
+    pytest-cov
 
 commands =
-    pytest -n auto
+    pytest --cov=cocotbext --cov=tests --cov-branch -n auto
+    bash -c 'find . -type f -name "\.coverage" | xargs coverage combine --append'
+
+whitelist_externals =
+    bash
+
+# combine if paths are different
+[coverage:paths]
+source =
+    cocotbext/
+    /*/cocotbext
+
+# do not report dependencies
+[coverage:report]
+omit = 
+   .tox/*