[RFP] REST API unit testing

[danieltsoukup]

Is your feature request related to a problem? Please describe.
Currently we are very thin on unit testing, particularly the API call functionalities.

Describe the solution you'd like
PROPOSE a solution for setting up mock APIs locally that mirror the WebCommand setup and cover the current data loading functionality by unit tests. Feel free to comment ⬇️ The outcome of this ticket will be a detailed description of the API testing and corresponding tickets organized under a new epic.

Additional context
The API documentation.

[mbechtel]

More extensive and accurate API documentation can be found in the Google Doc at:
https://docs.google.com/document/d/1CJ5xTEEhl2W9Ikjd6QiF1yvooPhU_E1yJJCPvLu234s/