TestingCancelWithDoubles.swift

func test_cancellAllTasks_givenExistsActiveTasks_shouldCancellAllOfThem() {
  let session = URLSessionSpy()
  let sut = Network(session: session)
        
  let loremTask = URLSessionDataTaskSpy()
  let ipsumTask = URLSessionDataTaskSpy()
  session.tasksToBeReturned = [loremTask, ipsumTask]        

  sut.cancelAllTasks()
        
  XCTAssertEqual(ipsumTask.cancelCalled, true)
  XCTAssertEqual(loremTask.cancelCalled, true)
}