Index.test.js file missing tests
I was looking for any sort of testing structure or practices in this project and saw this [index.test.js](https://github.com/r-spacex/SpaceX-API/blob/master/tests/index.test.js)  file. It looks to have a trivial example of how a test should be structured. Seems to me that there are tests missing. Is that the case or is there a file that I am not seeing? I saw some data issues opened up for some missing fields being returned by the api and thought that some tests would be a good way to test this. 

Thanks!