测试优化
我们把所有的代码写在一个函数里面不利于复用，前面我们只写了一个测试用例，但如果要写多个测试用例时会发现，重置数据库这个操作是很多地方会重复使用的，所以我们需要把一些可以重复使用的逻辑抽离出来，以方便写更多的测试。
把数据库重置这一部分抽出到Application+Testable.swift中
Swift
import Vapor
extension Application {
static func testable(envArgs: [String]? = nil) throws -> Application {
// 创建默认配置对象
var config = Config.default()
// 测试环境
var env = Environment.testing
// 创建默认服务对象
var services = Services.default()
if let environmentArgs = envArgs {
env.arguments = environmentArgs
}
// 使用 config和env来配置服务
try App.configure(&config, &env, &services)
// 使用config、env和services来初始化一个应用对象
let app = try Application(config: config, environment: env, services: services)
// 作一些应用初始化之后要做的工作
try App.boot(app)
return app
}
static func reset() throws {
let revertEnvironmentArgs = ["vapor", "revert", "--all", "-y"]
try Application.testable(envArgs: revertEnvironmentArgs).asyncRun().wait()
let migrateEnvironmentArgs = ["vapor", "migrate", "-y"]
try Application.testable(envArgs: migrateEnvironmentArgs).asyncRun().wait()
}
}
抽出这部分逻辑后，之前的那个测试用例重置数据库的部分就可以简化为一句话：
UserTests.swift
Swift
...
func testUsersCanBeRetrievedFromAPI() throws {
// 重置数据库
try Application.reset()
// 可测试
let app = try Application.testable()
...
}
...
再进一步抽离一些可以复用的逻辑，发现发送请求和获取响应也是可以复用的，逻辑都抽离到Application+testable.swift中：
Swift
...
// 因为模板函数不接收nil，所有定义一个空内容来代替
struct EmptyContent: Content {}
func sendRequest<T>(
to path: String,
method: HTTPMethod,
headers: HTTPHeaders = .init(),
body: T? = nil
) throws -> Response where T: Content {
// 创建一个和发送到app的HTTP请求
let request = HTTPRequest(method: method,
url: URL(string: path)!,
headers: headers)
let wrappedRequest = Request(http: request, using: self)
if let body = body {
try wrappedRequest.content.encode(body)
}
// 因为app本身没有正式运行，所以这里手动进行j响应
let responder = try self.make(Responder.self)
return try responder.respond(to: wrappedRequest).wait()
}
func sendRequest(
to path: String,
method: HTTPMethod,
headers: HTTPHeaders = .init()
) throws -> Response {
let emptyContent: EmptyContent? = nil
return try sendRequest(to: path,
method: method,
headers: headers,
body: emptyContent)
}
func sendRequest<T>(
to path: String,
method: HTTPMethod,
headers: HTTPHeaders,
data: T
) throws where T: Content {
_ = try sendRequest(to: path,
method: method,
headers: headers,
body: data)
}
func getResponse<C, T>(
to path: String,
method: HTTPMethod = .GET,
headers: HTTPHeaders = .init(),
data: C? = nil,
decodeTo type: T.Type
) throws -> T where C: Content, T: Decodable {
let response = try self.sendRequest(to: path,
method: method,
headers: headers,
body: data)
// 从响应数据中解析出用户数据，也即从数据库中检索出来的用户数据
return try response.content.decode(type).wait()
}
func getResponse<T> (
to path: String,
method: HTTPMethod = .GET,
headers: HTTPHeaders = .init(),
decodeTo type: T.Type
) throws -> T where T: Decodable {
let emptyContent: EmptyContent? = nil
return try self.getResponse(to: path,
method: method,
headers: headers,
data: emptyContent,
decodeTo: type)
}
...
将这些逻辑抽到Application+testable.swift中后，原来的测试用例简化为：
Swift
func testUsersCanBeRetrievedFromAPI() throws {
// 重置数据库
try Application.reset()
// 可测试
let app = try Application.testable()
// 创建一个app到PostgreSQL数据库的连接，表示app使用PostgreSQL数据库连接成功
let conn = try app.newConnection(to: .psql).wait()
// 定义测试数据
let expectedName = "Alice"
let expectedUsername = "alice"
// 创建两个用户数据，并保存进数据库中
let user = User(name: expectedName, username: expectedUsername)
let savedUser = try user.save(on: conn).wait()
_ = try User(name: "Luke", username: "lukes").save(on: conn).wait()
// 发请求并获得响应
let users = try app.getResponse(to: "/api/users", decodeTo: [User].self)
// 进行验证
XCTAssertEqual(users.count, 2)
XCTAssertEqual(users[0].name, savedUser.name)
XCTAssertEqual(users[0].username, savedUser.username)
XCTAssertEqual(users[0].id, savedUser.id)
// 关闭对数据库的连接，停止使用数据库
conn.close()
}
再考虑把创建测试数据的部分抽离到Models+testable.swift中：
Swift
import Vapor
import FluentPostgreSQL
extension User {
static func create(
name: String = "Luke",
username: String = "lukes",
on connection: PostgreSQLConnection) throws -> User {
let user = User(name: name, username: username)
return try user.save(on: connection).wait()
}
}
再结合XCTest测试框架的setUp和tearDown函数，最终测试用例简化如下：
UserTests.swit
Swift
@testable import App
import XCTest
import Vapor
import FluentPostgreSQL
final class UserTests: XCTestCase {
let usersName = "Alice"
let usersUsername = "alice"
let usersURI = "/api/users/"
var app: Application!
var conn: PostgreSQLConnection!
override func setUp() {
// 重置数据库
try! Application.reset()
// 可测试
app = try! Application.testable()
// 创建一个app到PostgreSQL数据库的连接，表示app使用PostgreSQL数据库连接成功
conn = try! app.newConnection(to: .psql).wait()
}
override func tearDown() {
// 关闭对数据库的连接，停止使用数据库
conn.close()
}
func testUsersCanBeRetrievedFromAPI() throws {
// 创建两个测试用户数据
let user = try User.create(name: usersName,
username: usersUsername,
on: conn)
_ = try User.create(on: conn)
// 发请求并获得响应
let users = try app.getResponse(to: usersURI, decodeTo: [User].self)
// 进行验证
XCTAssertEqual(users.count, 2)
XCTAssertEqual(users[0].name, usersName)
XCTAssertEqual(users[0].username, usersUsername)
XCTAssertEqual(users[0].id, user.id)
}
}
这整个优化过程实在是教科书式的例子。有个这种优化，之后写其它的测试用例，代码会简洁很多。