Test coverage

[kamilsi]

To maintain high code quality and reliability in our "unbiased" project, we need to implement a test coverage tool that measures the coverage of both unit tests for the R package and end-to-end tests for the Plumber API. Additionally, displaying a test coverage badge on our repository's front page will provide a quick and transparent overview of our testing status to contributors and users.

Tasks to Complete

• Selecting a Test Coverage Tool: Research and select a tool that can effectively measure test coverage for both R package unit tests and Plumber API end-to-end tests. Consider tools like covr for R package unit tests and an appropriate tool for the Plumber API.
• Integration with Testing Frameworks: Ensure the tool integrates seamlessly with our existing testing frameworks and CI/CD pipeline.
• Badge Generation and Setup: Configure the tool to generate a test coverage badge. Set up the badge to display the current test coverage status on the repository's front page.
• Documentation and Guides: Update the project documentation to include information about the test coverage tool, how it works, and how to interpret the results.

[kamilsi]

Closed with #42