.. _your_first_dirac_code:

=====================
Your first DIRAC code
=====================

We will now code some very simple exercises, based on what we have seen in the previous section.

Exercise 1
----------

Code a python module in DIRAC.Core.Utilities.checkCAOfUser where there is only the following function:


.. code-block:: python

   def checkCAOfUser(user, CA):
     """ user, and CA are string
     """

This function should:

* Get from the CS the registered Certification Authority for the user
* if the CA is the expected one return S_OK, else return S_ERROR

To code this exercise, albeit very simple, we will use TDD (Test Driven Development),
and we will use the *mock* python packages, as explained in :ref:`testing_environment`.
What we will code here will be a real *unit test*, in the sense that we will test only this function, in isolation.
In general, it is always an excellent idea to code a unit test for every development you do.
We will put the unit test in DIRAC.Core.Utilities.test. The unit test has been fully coded already:


.. code-block:: python

   # imports
   import mock

   # sut
   from DIRAC.Core.Utilities.checkCAOfUser import checkCAOfUser

   gConfigMock = mock.MagicMock()
   <todo>


Now, try to run it. Then, code ``checkCAOfUser`` and run the test again.


Exercise 2
----------

As a continuation of the previous exercise, code a python script that will:

* call DIRAC.Core.Utilities.checkCAOfUser.checkCAOfUser
* log wih info or error mode depending on the result

Remember to start the script with:


.. code-block:: python

   #!/usr/bin/env python
   """ Some doc: what does this script should do?
   """
   from DIRAC.Core.Base.Script import Script
   Script.parseCommandLine()


Then run it.