Add test coverage

[manushak]

Types of changes

• [x] Enhancement (project structure, spelling, grammar, formatting)
• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

A description of the changes proposed in the Pull Request

• add full test coverage for all plugins except watt-time, there is a watt-time improvement PR where the logic has been changed
• add minor improvement

[narekhovhannisyan]

@manushak please provide unit test PRs in separate logical chunks like one for boavizta, the next one for ccf, and so on. It's difficult to review.