test & refactor Config.olderThan()

[buhtz]

Introduction

Welcome to the project. If you pick up this Issue because of the "HELP WANTED" please let us now and introduce your self, your skills and wishes if you are new to the project.

Skills to solve this Issue

• Unit teststing.
• Refactoring.

The problem

This is about the method config.py::Config.olderThan().

• It is not covered by any unit test.
• It does not belong to the class Config.

Your next steps

1. If this is your first contribution in this project please introduce
   your self and tell us about your skills, wishes and plans. Also let us
   know how you found the issue and the project.
2. Read the existing contributors documentation.
3. We can develop the next steps in the further discussion. Don't hesitate to ask.
4. See next section Solution.

Solution

1. First, write unit tests to cover the whole behavior of that method.
2. Improve the doc strings based on the things you learned about that method.
3. Move the method somewhere else. If there is no better idea, just move it to common/tools.py as a function.
4. Refactor the code without changing its behavior.