UnitTesting 单元测试

1. 测试分为两种及详细介绍测试书籍:

1.1 Unit Test : 单元测试

- test the business logic in your app : 测试应用中的业务逻辑

1.2 UI Test : 界面测试

- test the UI of your app : 测试应用中的界面

1.3 测试书籍网址:《Testing Swift》 https://www.hackingwithswift.com/store/testing-swift

2. ViewModel 单元测试

2.1 创建 ViewModel，UnitTestingBootcampViewModel.swift

import Foundation
import SwiftUI
import Combine

/// 单元测试 ViewModel
class UnitTestingBootcampViewModel: ObservableObject{
    @Published var isPremium: Bool
    @Published var dataArray: [String] = []
    @Published var selectedItem: String? = nil
    let dataService: NewDataServiceProtocol
    var cancellable = Set<AnyCancellable>()
    
    init(isPremium: Bool, dataService: NewDataServiceProtocol = NewMockDataService(items: nil)) {
        self.isPremium = isPremium
        self.dataService = dataService
    }
    
    /// 添加子项
    func addItem(item: String){
        // 为空不往下执行
        guard !item.isEmpty else { return }
        self.dataArray.append(item)
    }
    
    /// 选中项
    func selectItem(item: String){
        if let x = dataArray.first(where: {$0 == item}){
            selectedItem = x
        }else{
            selectedItem = nil
        }
    }
    
    /// 保存项
    func saveItem(item: String) throws{
        guard !item.isEmpty else{
            throw DataError.noData
        }
        
        if let x = dataArray.first(where: {$0 == item}){
            print("Save item here!!! \(x)")
        } else {
            throw DataError.itemNotFound
        }
    }
    
    /// 错误信息
    enum DataError: LocalizedError{
        case noData
        case itemNotFound
    }
    
    /// 请求返回数据
    func downloadWithEscaping() {
        dataService.downloadItemsWithEscaping { [weak self] returnedItems in
            self?.dataArray = returnedItems
        }
    }
    
    /// 下载用到的组合
    func downloadWithCombine() {
        dataService.downloadItemsWithCombine()
            .sink { _ in
                
            } receiveValue: { [weak self] returnedItems in
                self?.dataArray = returnedItems
            }
            .store(in: &cancellable)
    }
}

2.2 创建测试文件

当创建项目时，没有选择 Include Tests/包含测试选项时，需要添加文件去对应项目，不然测试文件会报 No such module 'XCTest' 编译错误

添加单元测试文件:

方法一 : 选择项目 -> 菜单栏 Editor -> Add Target... -> 弹出对话框，选择 Test 栏下 -> Unit Testing Bundle -> 填写信息/可默认 -> Finish，完成创建单元测试文件。

方法二 : 选择项目，点击 PROJECT 列，最下的 + 按钮，弹出对话框，选择 Test 栏下，后面步骤与上一致

创建单元测试文件 UnitTestingBootcampViewModel_Tests.swift

import XCTest
import Combine
/// 导入项目
@testable import SwiftfulThinkingAdvancedLearning

// 《Testing Swift》 测试书籍
// 书籍网址: https://www.hackingwithswift.com/store/testing-swift
// Naming Structure: test_UnitOfWork_StateUnderTest_ExpectedBehavior -  结构体命名: 测试_工作单元_测试状态_预期的行为
// Naming Structure: test_[struct or class]_[variable or function]_[expected result] - 测试_[结构体 或者 类的名称]_[类中的变量名 或者 函数名称]_[预期结果 预期值]
// Testing Structure: Given, When, Then - 测试结构: 给定，什么时候，然后

final class UnitTestingBootcampViewModel_Tests: XCTestCase {
    /// 解决多次引用相同的类
    var viewModel: UnitTestingBootcampViewModel?
    var cancellables = Set<AnyCancellable>()
    
    /// 开始设置数据
    override func setUpWithError() throws {
        // Put setup code here. This method is called before the invocation of each test method in the class.
        viewModel = UnitTestingBootcampViewModel(isPremium: Bool.random())
    }
    
    /// 结束重置数据
    override func tearDownWithError() throws {
        // Put teardown code here. This method is called after the invocation of each test method in the class.
        viewModel = nil
        cancellables.removeAll()
    }
    
    /// 单元测试函数名，根据命名规则命名：测试_类名称_是否高质量_应该为真
    func test_UnitTestingBootcampViewModel_isPremium_shouldBeTrue(){
        // Given
        let userIsPremium: Bool = true
        
        // When
        let vm = UnitTestingBootcampViewModel(isPremium: userIsPremium)
        
        // Then
        XCTAssertTrue(vm.isPremium)
    }
    
    /// 单元测试函数名 根据命名规则命名：测试_类名称_是否高质量_应该为假
    func test_UnitTestingBootcampViewModel_isPremium_shouldBeFalse(){
        // Given
        let userIsPremium: Bool = false
        
        // When
        let vm = UnitTestingBootcampViewModel(isPremium: userIsPremium)
        
        // Then
        XCTAssertFalse(vm.isPremium)
    }
    
    /// 单元测试函数名 根据命名规则命名：测试_类名称_是否高品质_注入值
    func test_UnitTestingBootcampViewModel_isPremium_shouldBeInjectedValue(){
        // Given
        let userIsPremium: Bool = Bool.random()
        
        // When
        let vm = UnitTestingBootcampViewModel(isPremium: userIsPremium)
        
        // Then
        XCTAssertEqual(vm.isPremium, userIsPremium)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 注入值_压力 / for 循环
    func test_UnitTestingBootcampViewModel_isPremium_shouldBeInjectedValue_stress(){
        for _ in 0 ..< 10 {
            // Given
            let userIsPremium: Bool = Bool.random()
            // When
            let vm = UnitTestingBootcampViewModel(isPremium: userIsPremium)
            // Then
            XCTAssertEqual(vm.isPremium, userIsPremium)
        }
    }
    
    /// 单元测试函数名 根据命名规则命名 - 数组_预期值：为空
    func test_UnitTestingBootcampViewModel_dataArray_shouldBeEmpty(){
        // Given
        
        // When
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // Then 断言 = 判定
        XCTAssertTrue(vm.dataArray.isEmpty)
        XCTAssertEqual(vm.dataArray.count, 0)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 数组_预期值：添加项
    func test_UnitTestingBootcampViewModel_dataArray_shouldAddItems(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let loopCount: Int = Int.random(in: 1..<100)
        
        for _ in 0 ..< loopCount{
            vm.addItem(item: UUID().uuidString)
        }
        
        // Then 断言 = 判定
        XCTAssertTrue(!vm.dataArray.isEmpty)
        XCTAssertFalse(vm.dataArray.isEmpty)
        XCTAssertEqual(vm.dataArray.count, loopCount)
        XCTAssertNotEqual(vm.dataArray.count, 0)
        // GreaterThan 大于
        XCTAssertGreaterThan(vm.dataArray.count, 0)
        // XCTAssertGreaterThanOrEqual
        // XCTAssertLessThan
        // XCTAssertLessThanOrEqual
    }
    
    /// 单元测试函数名 根据命名规则命名 - 数组_预期值：添加空白字符
    func test_UnitTestingBootcampViewModel_dataArray_shouldNotAddBlankString(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        vm.addItem(item: "")
        
        // Then 断言 = 判定
        XCTAssertTrue(vm.dataArray.isEmpty)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 数组_预期值：添加空白字符
    func test_UnitTestingBootcampViewModel_dataArray_shouldNotAddBlankString2(){
        // Given
        guard let vm = viewModel else {
            XCTFail()
            return
        }
        
        // When
        vm.addItem(item: "")
        
        // Then 断言 = 判定
        XCTAssertTrue(vm.dataArray.isEmpty)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 选中项_预期值：开始为空
    func test_UnitTestingBootcampViewModel_selectedItem_shouldStartAsNil(){
        // Given
        
        // When
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // Then 断言 = 判定
        XCTAssertTrue(vm.selectedItem == nil)
        XCTAssertNil(vm.selectedItem)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 选中项_预期值：应该为空 当选择无效项
    func test_UnitTestingBootcampViewModel_selectedItem_shouldBeNilWhenSelectingInvalidItem(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // Select valid item : 选择有效项
        let newItem = UUID().uuidString
        vm.addItem(item: newItem)
        vm.selectItem(item: newItem)
        
        // Select invalid item : 选择无效项
        // When
        vm.selectItem(item: UUID().uuidString)
        
        // Then 断言 = 判定
        XCTAssertNil(vm.selectedItem)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 选中项_预期值：应该选中
    func test_UnitTestingBootcampViewModel_selectedItem_shouldBeSelected(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let newItem = UUID().uuidString
        vm.addItem(item: newItem)
        vm.selectItem(item: newItem)
        
        // Then 断言 = 判定
        XCTAssertNotNil(vm.selectedItem)
        XCTAssertEqual(vm.selectedItem, newItem)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 选中项_预期值：选中_压力测试
    func test_UnitTestingBootcampViewModel_selectedItem_shouldBeSelected_stress(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let loopCount: Int = Int.random(in: 1..<100)
        var itemsArray: [String] = []
        
        for _ in 0 ..< loopCount {
            let newItem = UUID().uuidString
            vm.addItem(item: newItem)
            itemsArray.append(newItem)
        }
        
        // 随机取一个字符串
        let randomItem = itemsArray.randomElement() ?? ""
        // 检查字符串不为空
        XCTAssertFalse(randomItem.isEmpty)
        vm.selectItem(item: randomItem)
        
        // Then 断言 = 判定
        XCTAssertNotNil(vm.selectedItem)
        XCTAssertEqual(vm.selectedItem, randomItem)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 保存项_预期值：输出错误异常_元素没找到
    func test_UnitTestingBootcampViewModel_saveItem_shouldThrowError_itemNotFound(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let loopCount: Int = Int.random(in: 1..<100)
        for _ in 0 ..< loopCount {
            vm.addItem(item: UUID().uuidString)
        }
        
        // Then 断言 = 判定
        XCTAssertThrowsError(try vm.saveItem(item: UUID().uuidString))
        XCTAssertThrowsError(try vm.saveItem(item: UUID().uuidString), "Should throw Item Not Found error!") { error in
            // 返回错误
            let returnedError = error as? UnitTestingBootcampViewModel.DataError
            // 判断错误是否相同
            XCTAssertEqual(returnedError, UnitTestingBootcampViewModel.DataError.itemNotFound)
        }
    }
    
    /// 单元测试函数名 根据命名规则命名 - 保存项_预期值：输出错误异常_没数据
    func test_UnitTestingBootcampViewModel_saveItem_shouldThrowError_noData(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let loopCount: Int = Int.random(in: 1..<100)
        for _ in 0 ..< loopCount {
            vm.addItem(item: UUID().uuidString)
        }
        
        // Then 断言 = 判定
        do {
            try vm.saveItem(item: "")
        } catch let error {
            // 返回错误
            let returnedError = error as? UnitTestingBootcampViewModel.DataError
            // 判断错误是否相同
            XCTAssertEqual(returnedError, UnitTestingBootcampViewModel.DataError.noData)
        }
    }
    
    /// 单元测试函数名 根据命名规则命名 - 保存项_预期值：保存选项
    func test_UnitTestingBootcampViewModel_saveItem_shouldSaveItem(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let loopCount: Int = Int.random(in: 1..<100)
        var itemsArray: [String] = []
        
        for _ in 0 ..< loopCount {
            let newItem = UUID().uuidString
            vm.addItem(item: newItem)
            itemsArray.append(newItem)
        }
        
        // 随机取一个字符串
        let randomItem = itemsArray.randomElement() ?? ""
        // 检查字符串不为空
        XCTAssertFalse(randomItem.isEmpty)
        // Then 断言 = 判定
        XCTAssertNoThrow(try vm.saveItem(item: randomItem))
        do {
            try vm.saveItem(item: randomItem)
        } catch  {
            XCTFail()
        }
    }
    
    /// 单元测试函数名 根据命名规则命名 - 下载数据_预期值：返回选项
    func test_UnitTestingBootcampViewModel_downloadWithEscaping_shouldReturnItems(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let expectation = XCTestExpectation(description: "Should return items after 3 seconds")
        // dropFirst: 删除第一个发布 数组值，因为初始化为空数组，取的是第二个数组，模拟服务数据返回的数组
        vm.$dataArray
            .dropFirst()
            .sink { returnedItems in
                expectation.fulfill()
            }
            .store(in: &cancellables)
        
        vm.downloadWithEscaping()
        
        // Then 断言 = 判定 GreaterThan：大于
        // 为了安全获取到值，设置等待 5 秒
        wait(for: [expectation], timeout: 5)
        XCTAssertGreaterThan(vm.dataArray.count, 0)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 下载数据组合_预期值：返回选项
    func test_UnitTestingBootcampViewModel_downloadWithCombine_shouldReturnItems(){
        // Given
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random())
        
        // When
        let expectation = XCTestExpectation(description: "Should return items after a seconds")
        // dropFirst: 删除第一个发布 数组值，因为初始化为空数组，取的是第二个数组，模拟服务数据返回的数组
        vm.$dataArray
            .dropFirst()
            .sink { returnedItems in
                expectation.fulfill()
            }
            .store(in: &cancellables)
        
        vm.downloadWithCombine()
        
        // Then 断言 = 判定 GreaterThan：大于
        // 为了安全获取到值，设置等待 5 秒
        wait(for: [expectation], timeout: 5)
        XCTAssertGreaterThan(vm.dataArray.count, 0)
    }
    
    /// 单元测试函数名 根据命名规则命名 - 下载数据组合_预期值：返回选项
    func test_UnitTestingBootcampViewModel_downloadWithCombine_shouldReturnItems2(){
        // Given
        let items: [String] = [UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString]
        let dataService: NewDataServiceProtocol = NewMockDataService(items: items)
        let vm = UnitTestingBootcampViewModel(isPremium: Bool.random(), dataService: dataService)
        
        // When
        let expectation = XCTestExpectation(description: "Should return items after a seconds")
        // dropFirst: 删除第一个发布 数组值，因为初始化为空数组，取的是第二个数组，模拟服务数据返回的数组
        vm.$dataArray
            .dropFirst()
            .sink { returnedItems in
                expectation.fulfill()
            }
            .store(in: &cancellables)
        
        vm.downloadWithCombine()
        
        // Then 断言 = 判定 GreaterThan：大于
        // 为了安全获取到值，设置等待 5 秒
        wait(for: [expectation], timeout: 5)
        XCTAssertGreaterThan(vm.dataArray.count, 0)
        XCTAssertEqual(vm.dataArray.count, items.count)
    }
}

3. 模拟请求数据单元测试

3.1 创建模拟请求数据类 NewMockDataService.swift

import Foundation
import SwiftUI
import Combine

/// 定义协议
protocol NewDataServiceProtocol{
    func downloadItemsWithEscaping(completion: @escaping (_ items: [String]) -> ())
    func downloadItemsWithCombine() -> AnyPublisher<[String], Error>
}

/// 实现模拟请求数据
class NewMockDataService: NewDataServiceProtocol {
    let items: [String]
    
    init(items: [String]?) {
        self.items = items ?? [
            "ONE", "TWO", "THREE"
        ]
    }
    
    /// 模拟网络下载数据 escaping: 转义字符
    func downloadItemsWithEscaping(completion: @escaping (_ items: [String]) -> ()) {
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            completion(self.items)
        }
    }
    
    /// 下载组合
    func downloadItemsWithCombine() -> AnyPublisher<[String], Error> {
        // 数据转换
        Just(self.items)
            .tryMap({ publishedItems in
                guard !publishedItems.isEmpty else {
                    throw URLError(.badServerResponse)
                }
                return publishedItems
            })
            .eraseToAnyPublisher()
    }
}

3.2 创建单元测试类 NewMockDataService_Tests.swift

import XCTest
import Combine
/// 导入项目
@testable import SwiftfulThinkingAdvancedLearning

final class NewMockDataService_Tests: XCTestCase {
    /// 随时取消控制器
    var cancellable = Set<AnyCancellable>()
    
    override func setUpWithError() throws {
        // Put setup code here. This method is called before the invocation of each test method in the class.
    }

    override func tearDownWithError() throws {
        // Put teardown code here. This method is called after the invocation of each test method in the class.
        cancellable.removeAll()
    }
    
    //  单元测试函数名 根据命名规则命名 - 测试_类名_初始化_预期值：正确的设置值
    func test_NewMockDataService_init_doesSetValuesCorrectly() {
        // 执行
        // Given: 给定
        let items: [String]? = nil
        let items2: [String]? = []
        let items3: [String]? = [UUID().uuidString, UUID().uuidString]
        
        // When: 时间
        let dataService = NewMockDataService(items: items)
        let dataService2 = NewMockDataService(items: items2)
        let dataService3 = NewMockDataService(items: items3)
        
        // Then 然后
        XCTAssertFalse(dataService.items.isEmpty)
        XCTAssertTrue(dataService2.items.isEmpty)
        XCTAssertEqual(dataService3.items.count, items3?.count)
    }
    
    //  单元测试函数名 根据命名规则命名 - 测试_类名_下载转换数据项_预期值：正确的设置值
    func test_NewMockDataService_downloadItemsWithEscaping_doesReturnValues() {
        // 执行
        // Given: 给定
        let dataService = NewMockDataService(items: nil)
        
        // When: 时间
        var items: [String] = []
        let expectation = XCTestExpectation()
        dataService.downloadItemsWithEscaping { returnedItems in
            items = returnedItems
            expectation.fulfill()
        }
        
        // Then 然后
        // 等待 5 秒
        wait(for: [expectation], timeout: 5)
        // 断言两个数组大小一样
        XCTAssertEqual(items.count, dataService.items.count)
    }
    
    //  单元测试函数名 根据命名规则命名 - 测试_类名_下载数据项组合_预期值：正确的设置值
    func test_NewMockDataService_downloadItemsWithCombine_doesReturnValues() {
        // 执行
        // Given: 给定
        let dataService = NewMockDataService(items: nil)
        
        // When: 时间
        var items: [String] = []
        let expectation = XCTestExpectation()
        
        // 下载组合控制
        dataService.downloadItemsWithCombine()
            .sink { completion in
                switch completion{
                case .finished:
                    expectation.fulfill()
                case .failure:
                    XCTFail()
                }
            } receiveValue: {returnedItems in
                // fulfill: 完成
                items = returnedItems
            }
            .store(in: &cancellable)
        // Then 然后
        // 等待 5 秒
        wait(for: [expectation], timeout: 5)
        // 断言两个数组大小一样
        XCTAssertEqual(items.count, dataService.items.count)
    }
    
    //  单元测试函数名 根据命名规则命名 - 测试_类名_下载数据项组合_预期值：确实失败
    func test_NewMockDataService_downloadItemsWithCombine_doesFail() {
        // 执行
        // Given: 给定
        let dataService = NewMockDataService(items: [])
        
        // When: 时间
        var items: [String] = []
        let expectation = XCTestExpectation(description: "Does throw an error")
        let expectation2 = XCTestExpectation(description: "Does throw URLError.badServerResponse")
        // 下载组合控制
        dataService.downloadItemsWithCombine()
            .sink { completion in
                switch completion{
                case .finished:
                    XCTFail()
                case .failure(let error):
                    expectation.fulfill()
                    
                    //let urlError = error as? URLError
                    // 断言，判定
                    //XCTAssertEqual(urlError, URLError(.badServerResponse))
                    
                    // 错误判断
                    if error as? URLError == URLError(.badServerResponse) {
                        expectation2.fulfill()
                    }
                }
            } receiveValue: {returnedItems in
                // fulfill: 完成
                items = returnedItems
            }
            .store(in: &cancellable)
        // Then 然后
        // 等待 5 秒
        wait(for: [expectation, expectation2], timeout: 5)
        // 断言两个数组大小一样
        XCTAssertEqual(items.count, dataService.items.count)
    }
}

4. 创建单元测试 View，调用测试的 ViewModel UnitTestingBootcampView.swift

import SwiftUI

/*
 1. Unit Test : 单元测试
 - test the business logic in your app : 测试应用中的业务逻辑
 
 2. UI  Test :  界面测试
 - test the UI of your app : 测试应用中的界面
 */

/// 单元测试
struct UnitTestingBootcampView: View {
    @StateObject private var vm: UnitTestingBootcampViewModel
    
    init(isPremium: Bool){
        _vm = StateObject(wrappedValue: UnitTestingBootcampViewModel(isPremium: isPremium))
    }
    
    var body: some View {
        Text(vm.isPremium.description)
    }
}

struct UnitTestingBootcampView_Previews: PreviewProvider {
    static var previews: some View {
        UnitTestingBootcampView(isPremium: true)
    }
}