Add Unit Tests

Are you willing to contribute it (Yes/No): Yes

**Describe the feature and the current behavior/state.**
Add unit tests so that we can setup github actions to ensure commits don't break existing functionality.

**Will this change the current API? How?**
No
**Who will benefit with this feature?**
Everyone that uses pgp-services as it helps ensure the stability as updates are committed.
**Miscellaneous Information**

The issue names no test files, entry points, or existing test command. Start by inspecting the repository structure to identify the service entry point and test tooling, then define coverage for current functionality before connecting it to GitHub Actions; done means repeatable unit tests run in CI without changing the API.

Written by the indexing model from the issue text.