Setup test directory

As we mentioned, we should implement tests for the functionalities we write. I was thinking to do it using the unittest package in the same way I did here.

I will take care of setting up one as an example with the suggested conventions. These same conventions/scheme should then be followed when we write the test classes for the functionalities we want to test.

Note: this issue is related to #3, since after we have the test suite in place we will have to instruct the CI scripts to run automatically the command for testing.