Introducing Swift Testing

If you are the lead developer of a large project involving many developers, it would not be practical for you to review everyone’s source code in detail, and in some cases, you would not be able to view the source code at all. Instead, you would issue specifications on what a class is supposed to do, and it would be the developer’s job to write the class for you.

As an example, let’s look at the initializer code for the JournalEntry class in the JRNL app:

init?(rating: Int, title: String, body: String, photo: UIImage? = nil, latitude: Double? = nil, longitude: Double? = nil) {
  if title.isEmpty || body.isEmpty || rating < 0 ||    rating > 5 {
    return nil
  }
  self.date = Date()
  self.rating = rating
  self.title = title
  self.body = body
  self.photoData = photo?.jpegData(compressionQuality: 1.0)
  self.latitude = latitude
  self.longitude = longitude
}

As you can see, you can only create valid JournalEntry...