Add unit tests for utility functions

[matt439]

ThothTech fork pull request: thoth-tech#68

Description

There are currently no unit tests for the functions listed under 'Utilities' in the SplashKit documentation. I have created exhaustive tests for each of these functions apart from display_dialog as it is generates purely graphical content and would be better suited for sktests.

In the process of creating the tests, I have identified issues with replace_all, rnd and rnd(min, max). I can consistently cause an infinite loop in replace_all, and an unhanded exception in the two overloads of rnd. Keeping those tests in skunit_tests will cause it to fail. As a compromise, I have left the tests in place and commented them. My intention is to create separate pull requests to rectify the faulty functions. Once they are fixed, the tests can be uncommented.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Adding the new tests was achieved by running cmake -G "Unix Makefiles" . followed by make when in the /splashkit-core/projects/cmake directory.

Testing Checklist

• Tested with skunit_tests

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• My changes generate no new warnings
• I have requested a review from ... on the Pull Request