Controller not being discovered in asp.net core F# - asp.net-core

Question

I am trying to setup a unit test in F# with asp.net core. with the code below. but the code to the server fails with a 404 Not found.
Is there a reason why the controller is being discovered by the framework ?
module Tests
open System
open Xunit
open Microsoft.AspNetCore.Builder
open Microsoft.AspNetCore.Hosting
open Microsoft.AspNetCore.Mvc
open Microsoft.Extensions.DependencyInjection
type Startup () =
member __.ConfigureServices(services: IServiceCollection) =
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2) |> ignore
member __.Configure(app: IApplicationBuilder, env: IHostingEnvironment) =
app.UseMvc() |> ignore
[<Route("api")>]
[<ApiController>]
type TestController() =
inherit ControllerBase()
[<HttpGet("testGet")>]
member __.TestGet() =
121221
[<HttpPost("testPost")>]
member __.TestPost() =
String.Empty
let buildHost(baseAdress:string) =
Microsoft.AspNetCore.WebHost
.CreateDefaultBuilder()
.UseStartup<Startup>()
.UseUrls(baseAdress)
.Build()
[<Fact>]
let ``My test`` () =
let baseAdress = "https://localhost:9000"
use host = buildHost(baseAdress)
host.RunAsync() |> ignore
let client = new System.Net.Http.HttpClient(BaseAddress = new System.Uri(baseAdress))
let result = client.GetAsync("api/testGet").Result
Assert.Equal(System.Net.HttpStatusCode.OK, result.StatusCode)
Assert.True(result.IsSuccessStatusCode, result.Content.ReadAsStringAsync().Result )
Here is the content of the fsproj File
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netcoreapp2.2</TargetFramework>
<IsPackable>false</IsPackable>
<GenerateProgramFile>false</GenerateProgramFile>
</PropertyGroup>
<ItemGroup>
<Compile Include="Tests.fs" />
</ItemGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.App" Version="2.2.2" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
<PackageReference Include="Microsoft.NETCore.App" Version="2.2.2" />
<PackageReference Include="xunit" Version="2.4.0" />
<PackageReference Include="xunit.runner.visualstudio" Version="2.4.0" />
<PackageReference Include="coverlet.collector" Version="1.0.1" />
</ItemGroup>
</Project>

Answer 1

Except the reasons commented above by #Kirk Larkin, you need put your controller into a namespace instead of module directly.
namespace App //<------------- put your controller into a namespace
// ... open
type Startup () =
...
[<Route("api")>]
[<ApiController>]
type TestController() =
...
module Tests=
// ... open
let buildHost(baseAdress:string) =
Microsoft.AspNetCore.WebHost
.CreateDefaultBuilder()
.UseStartup<Startup>()
.UseUrls(baseAdress)
.Build()
[<Fact>]
let ``My test`` () =
...
Also note you're starting the server by an asynchronous method host.RunAsync() |> ignore. Although the above test code works fine for me, there's a chance your HttpClient will send requests before the server is ready. A good way is to add a reference to the Microsoft.AspNetCore.TestHost package and using the built-in TestHost instead:
let hostBuilder =
Microsoft.AspNetCore.WebHost
.CreateDefaultBuilder()
.UseStartup<Startup>()
use server = new Microsoft.AspNetCore.TestHost.TestServer(hostBuilder)
use client = server.CreateClient()
let result = client.GetAsync("api/testGet").Result // a quick & dirty test
Assert.Equal(System.Net.HttpStatusCode.OK, result.StatusCode)
Assert.True(result.IsSuccessStatusCode, result.Content.ReadAsStringAsync().Result )
[Edit]:
I'm now sure it is a behavior by design. See source code on GitHub:
// We only consider public top-level classes as controllers. IsPublic returns false for nested
// classes, regardless of visibility modifiers
if (!typeInfo.IsPublic)
{
return false;
}
Since the class within a F# module will be compiled into a nested class, it won't be considered as a Controller at all.

Answer 2

On top of the answer that #itminus provided. the issue can be resolved by configuring the application manager in configureServices like so
member this.ConfigureServices(services: IServiceCollection) =
services
.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.ConfigureApplicationPartManager(fun m ->
m.FeatureProviders.Add
{
new Microsoft.AspNetCore.Mvc.Controllers.ControllerFeatureProvider() with
member __.IsController (typeInfo:System.Reflection.TypeInfo) =
(typeof<ControllerBase>.IsAssignableFrom(typeInfo)) || base. IsController(typeInfo)
}
) |> ignore
services.AddRouteAnalyzer() |> ignore