Add more unit tests for the test-framework

[SupunS]

Issue to be solved

Many of the tests for the test-framework are in the cadence-tools repo. Because of that, certain regression issues are only caught when updating the downstream dependencies.

Suggested Solution

Write more unit tests for the APIs / basic functionalities in this repo, using the mock test framework.

[j1010001]

In addition, consider adding CI check for API breakage to Cadence-tools