Add instruction for pre-commit hook

README.md

@@ -17,3 +17,23 @@ Launch tests with
 ```sh
 python3 -m unittest
 ```
+
+# git hook
+To start tests automatically you can create a `pre-commit` file in `.git/hooks/` with the following content:
+```sh
+#!/usr/bin/env bash
+
+# run tests
+python3 -m unittest discover . --failfast
+# unittest exists with 0 if all tests passed, 1 otherwise.
+tests_failed=$?
+if [ ${tests_failed} -eq 1 ]; then
+	echo "Tests failed. Aborting commit"
+	exit 1
+fi
+
+exit 0
+```
+The hook should have execution right, `chmod 775 .git/hooks/pre-commit`.
+
+Maybe we can use the example here https://gist.github.com/orenshk/6cab23fcff847d704af7f3eec22b1ba6 as pre-commit hook to also format according to PEP8.