F# 如何为Saturn应用程序构建集成测试

我正在尝试为我使用构建的小型API构建一些集成测试

该API使用常见的

Saturn

计算表达式构建，如

应用程序

、

控制器

、

路由器

等

但是为了构建集成测试，我需要替换

应用程序

计算表达式（ce）和手工制作

WebHostBuilder

我的

应用程序

ce如下所示：

module Server 

let app =
    application {
        url ("http://0.0.0.0:" + port.ToString() + "/")
        use_router apiRouter
        memory_cache
        service_config configureSerialization
        use_gzip
        use_config (fun _ ->
            System.Environment.CurrentDirectory <- (System.Reflection.Assembly.GetExecutingAssembly()).Location
                                                   |> Path.GetDirectoryName
            let configurationRoot =
                ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appSettings.json")
                    .Build()
            let appConfig = FsConfig.AppConfig(configurationRoot)

            let dbPath =
                match appConfig.Get<AppSettings>() with
                | Ok settings when settings.DbConfig.Database.Contains(":memory:") -> settings.DbConfig.Database
                | Ok settings -> Path.Combine(System.Environment.CurrentDirectory, settings.DbConfig.Database)
                | Error _ -> failwithf "Invalid database path"
            { connectionString = dbPath |> sprintf "DataSource=%s;Version=3" })
    } 

上面的代码在我的API项目中，下面带有集成测试的代码在第二个项目中。后者的项目参考了前者

let configureApp (app : IApplicationBuilder) =
    app.UseGiraffe(Server.apiRouter) \\<-- The problem is here. Server.apiRouter is null!

let configureServices (services : IServiceCollection) =
    services.AddGiraffe() |> ignore

let builder = WebHostBuilder()
                .UseContentRoot(contentRoot) 
                .Configure(Action<IApplicationBuilder> configureApp)
                .ConfigureServices(configureServices)

let testServer = new TestServer(builder)

let client = testServer.CreateClient()

let! response = client.GetAsync "/"

test <@ HttpStatusCode.OK = response.StatusCode @> 

问题似乎出在app.usegirafe（Server.apiRouter）行上<代码>apiRouter是在API项目的

服务器

模块中定义的-但是当此代码在测试项目

服务器中运行时。apiRouter

为

空

但是，如果我将测试代码移动到与

API

相同的项目中，那么测试就可以完美地工作

---

如果从测试项目调用，

apiRouter

计算表达式为什么会为

null

事实证明，这与土星毫无关系。这一切都与

F#

启动

模块的方式有关

正如参考文章中所建议的那样。我只是简单地添加了一个
[]
函数，一切都按预期工作

let configureApp (app : IApplicationBuilder) =
    app.UseGiraffe(Server.apiRouter) \\<-- The problem is here. Server.apiRouter is null!

let configureServices (services : IServiceCollection) =
    services.AddGiraffe() |> ignore

let builder = WebHostBuilder()
                .UseContentRoot(contentRoot) 
                .Configure(Action<IApplicationBuilder> configureApp)
                .ConfigureServices(configureServices)

let testServer = new TestServer(builder)

let client = testServer.CreateClient()

let! response = client.GetAsync "/"

test <@ HttpStatusCode.OK = response.StatusCode @> 

System.InvalidOperationException' occurred in System.Private.CoreLib.dll but was not handled in user code: 'A suitable constructor for type 'Giraffe.Middleware+GiraffeMiddleware' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.'