Test Coverage: Improve test coverage

[manrajgrover]

Description

Currently, test coverage is at 90% which can surely be improved. Possibly, one of the easiest ways for someone to contribute to this library.

[giancarloGiuffra]

hi, I will be happy to help with this. I have run the coverage report. I'll start with the file tangent_between_circles.js

[manrajgrover]

@giancarloGiuffra Awesome! Feel free to ping me here if you face any issue

[mikemolenda]

I can pick up ternary_search.js

[jonatan5524]

I can pick interpolation_search.js