diff --git a/Makefile b/Makefile
index cf85308e4ebcf5fe2fb883977baa445ca7ed3169..2cbbe5847f5177121acecdcd343dbd253c4aa8e5 100644
--- a/Makefile
+++ b/Makefile
@@ -9,8 +9,11 @@ check:
 	flake8 muppet
 	mypy -p muppet
 
+# TODO only require coverage if `python -m pytest -VV | grep pytest-cov` return true
+PYTEST_FLAGS = --cov=muppet --cov-branch --cov-report=html
+
 test:
-	python -m pytest
+	python -m pytest $(PYTEST_FLAGS) tests
 
 clean:
 	-rm -r output