Hands-On Design Patterns with Swift

Fake test double: a simplified collaborator

A fake object is a simplified version of a collaborator, with similar or partial functionalities, but implemented in a simpler way. Considering a version of TaskManager that stores the tasks locally, using a store object as a collaborator, whose implementation is unknown to the TaskManager, it might be implemented as file-persistent on file or database-persistent with CoreData.

TaskManager relies on the store to persist the tasks:

class TaskManager {    private let store: TaskStore    init(store: TaskStore) {        self.store = store    }    func add(task: Task) {        store.add(task: task)    }    var count: Int {        return store.allTasks.count    }}

TaskStore has the following interface:

protocol TaskStore { var allTasks: ...