In this section, we will demonstrate how to add a new feature with tests to an existing legacy code base. The codebase is an example, it is not a real project.
The example function we will be working with does the following:
- takes a user from the app as an input, from now on referred to as friend
- determines the currently logged in user
- determines if the friend passed in as an input is a friend of the logged in user
- if so, the function will get the trips belonging to the friend
- all trips have the following attributes:
- id
- location
- startDate
Our task in this example scenario is to calculate the days left before the startDate of each trip, and add a daysLeft property to each trip.
The task also requires that we return NA for daysLeft if there is no startDate property on the trip