src/coding_practices/python/python_test.md

+**Page author:** @cmoineau
+
+# Python tests
+
+## Writing tests
+
+To test the library, we are using the framework [unittest](https://docs.python.org/3.7/library/unittest.html).
+
+If you develop a new feature to the python API **you have to write unit test**.
+
+If you want to create your own test, you can create a script in the folder `python/tests`.
+
+Your script name have to be named `test_*.py` in order to be automatically run by the `unittest` framework.
+
+Then follow this template :
+
+```
+import unittest
+
+class test_name(unittest.TestCase):
+    """
+    The class needs to inherit unittest.TestCase, the name doesn't matter and the class doesn't need to be instantiated.
+    """
+
+    def setUp(self):
+        """
+        Method called before each test
+        """
+        pass
+
+    def tearDown(self):
+        """
+        Method called after a test, even if it failed.
+        Can be used to clean variables
+        """
+        pass
+
+    def test_X(self):
+        """
+        Method called to test a functionality. It needs to be named test_* to be called.
+        """
+
+        """
+        To test the functions you can use one of the following method :
+        - self.assertEqual(a, b)
+        - self.assertNotEqual(a, b)
+        - self.assertTrue(a)
+        - self.assertFalse(a)
+        - self.assertIs(a, b)
+        - self.assertIsNot(a, b)
+        - self.assertIsNotNone(a)
+        - self.assertIn(a, b)
+        - self.assertNotIn(a, b)
+        - self.assertIsInstance(a, b)
+        """
+
+        """
+        You can use the following decorator :
+        - @unittest.skip(display_text)
+        - @unittest.skipIf(cond, display_text)
+        - @unittest.skipUnless(cond, display_text)
+        - @unittest.expectedFailure()
+        """
+
+        """
+        You can test that a function raises error by putting it in a block :
+        with self.assertRaises(TypeError):
+        You can replace TypeError by the type of message you are expecting
+        """
+        pass
+
+if __name__ == '__main__':
+    """
+    You need to add this line for the tests to be run.
+    """
+    unittest.main()
+```
+
+## Running tests
+
+If you want to **run the unit test** use the command :
+
+```
+python -m unittest discover -s tests -v 1> /dev/null
+```
+
+If you wan to only run your test, you can just type the command
+
+```
+python SCRIPT_PATH
+```
+
+### Tip: run you tests with pytest for a cleaner ouput :sunflower: 
+
+Pytests understands unittests and renders a more concise output
+
+```
+pip install pytest
+python -m pytest <your_test>.py
+```
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