diff --git a/implementations/javascript/.gitignore b/implementations/javascript/.gitignore
index 504afef..2d8d77e 100644
--- a/implementations/javascript/.gitignore
+++ b/implementations/javascript/.gitignore
@@ -1,2 +1,4 @@
+.nyc_output/
+coverage/
 node_modules/
 package-lock.json
diff --git a/implementations/python/.gitignore b/implementations/python/.gitignore
index 0d20b64..8aa07c2 100644
--- a/implementations/python/.gitignore
+++ b/implementations/python/.gitignore
@@ -1 +1,3 @@
 *.pyc
+.coverage
+htmlcov/
diff --git a/implementations/python/Makefile b/implementations/python/Makefile
index 8885663..cf6523a 100644
--- a/implementations/python/Makefile
+++ b/implementations/python/Makefile
@@ -1,3 +1,8 @@
 test:
 	python2 -m unittest test_preserves
 	python3 -m unittest test_preserves
+
+coverage:
+	python2-coverage run --branch -m unittest test_preserves
+	python3-coverage run --branch -m unittest test_preserves
+	python3-coverage html