Add contract and solo tests

This PR reloves the issues (#1614) and (#1613).

Includes the feature for writing solo tests for the contracts given.

Change checklist

Tick the boxes that are relevant to your changes, and delete any items that are not.

[x] I have followed the contribution guidelines for this project
[X] I have performed a self-review of my own code
[ ] I have selected the develop branch as the target branch
[X] I have commented my code, particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation
[ ] I have added tests that prove my fix is effective or that my feature works
[ ] I have checked that new and existing unit tests pass locally with my changes