Test Coverage

Created by: tannakartikey

Describe the solution you'd like

The project is attracting lots of contributors and the data we display is critical. So I thought if we add some test coverage to the codebase it will be great. That way we will be sure that the calculations are correct, new changes are not breaking anything and we will be confident while refactoring... (you know the benefits of the tests)

Since our project is open source we can use any CI/CD tool like Travis or use Zeit's build step.