Add documentation for testing

backend/README.md

@@ -7,4 +7,5 @@ The documentation is split in several files for better structure.
 Table of Contents:
 
 - [Installation](docs/installation.md)
-- [Guidelines](docs/guidelines.md)
+- [Guidelines](docs/guidelines.md)
+- [Testing](docs/testing.md)

backend/docs/testing.md

@@ -0,0 +1,13 @@
+# Testing
+
+To execute the tests, you need to install pytest.
+
+```bash
+$ pip3 install pytest
+```
+
+Then, you can run the tests with:
+
+```bash
+$ pytest
+```