Move existing tests to a unit testing framework

Git has many existing end-to-end tests which are written in shell script. However, to unit test some of the internal libraries/functionality, we use helper binaries whose output is consumed by these shell scripts to compare the result obtained from those binaries with the expected result. This translation is costly due to many reasons. Therefore, this project aims port some of these existing unit tests to the newly merged TAP implementation of a unit testing framework, which allows for tests to be written solely in C, and does not require the shell script translation.