a2-13.swift

func test_create_todo() {

    //Given the name & status
    let name = "Todo1"
    let finished = false

    //When add todo
    let todo = sut.insertTodoItem(name: name, finished: finished)

    //Assert: return todo item
    XCTAssertNotNil( todo )
        
}

func test_fetch_all_todo() {

    //Given a storage with two todo

    //When fetch
    let results = sut.fetchAll()

    //Assert return five todo items
    XCTAssertEqual(results.count, 5)
        
}

func test_remove_todo() {

    //Given a item in persistent store
    let items = sut.fetchAll()
    let item = items[0]

    let numberOfItems = items.count

    //When remove a item
    sut.remove(objectID: item.objectID)
    sut.save()

    //Assert number of item - 1
    XCTAssertEqual(numberOfItemsInPersistentStore(), numberOfItems-1)

}

//Convenient method for getting the number of data in store now
func numberOfItemsInPersistentStore() -> Int {
    let request: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: "ToDoItem")
    let results = try! mockPersistantContainer.viewContext.fetch(request)
    return results.count
}