Expecto + FSharp: Error FS0433 : A function labeled with the 'EntryPointAttribute' attribute must be the last declaration in the last file in the compilation sequence.

[marcingolenia]

Describe the bug

Hi there! Thank you for working on this. I jumped to try this stuff right away once I read the article here: https://devblogs.microsoft.com/dotnet/mtp-adoption-frameworks/. Unfortunately it looks it doesn't work. I have "'EntryPointAttribute' attribute must be the last declaration in the last file ".

Steps To Reproduce

1. mkdir tests
2. cd tests
3. dotnet new console -lang "F#"
4. Paste fsproj stuff from the article. Here it is;

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <EnableExpectoTestingPlatformIntegration>true</EnableExpectoTestingPlatformIntegration>
    <OutputType>Exe</OutputType>
    <TestingPlatformDotnetTestSupport>true</TestingPlatformDotnetTestSupport>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="YoloDev.Expecto.TestSdk" Version="0.15.0" />
  </ItemGroup>
  <ItemGroup>
    <Compile Include="Test.fs" />
  </ItemGroup>
</Project>

5. Adjust the file name that was generated, here I have Test.fs.
6. Run dotnet build.
7. Experience the error Files in libraries or multiple-file applications must begin with a namespace or module declaration, e.g. 'namespace SomeNamespace.SubNamespace' or 'module SomeNamespace.SomeModule'. Only the last source file of an application may omit such a declaration.
8. It is the last source file but fine. Let's add the module. So we have sth like this:

module Tests

open Expecto

let tests =
    testList "Calculator Tests" [
        test "Add function returns sum" {
            let result = 4
            Expect.equal result 3 "Expected sum to be 3"
        }
    ]

[<EntryPoint>]
let main argv =
    runTestsWithArgs defaultConfig argv tests

9. Experience the The value or constructor 'runTestsWithArgs' is not defined. Maybe you want one of the following: runTestsWithCLIArgs runTestsWithCLIArgsAndCancel error.
10. change

    runTestsWithArgs defaultConfig argv tests

to

    runTestsWithCLIArgs [] argv tests

11. Experience A function labeled with the 'EntryPointAttribute' attribute must be the last declaration in the last file in the compilation sequence.

Expected behavior

It works.

Actual behavior

Errors.

Additional context

I am using Ubuntu. Also If you will remove EnableExpectoTestingPlatformIntegration attribute then it compiles. When I type dotnet run, it actually runs the tests. All in all Rider doesn't detect the tests, so the test explorer is empty.

[Evangelink]

Thanks for raising a feedback here @marcingolenia! I did fix the blogpost but I see it was not updated. I'll raise a feedback at Microsoft and I will edit this message with the proper code in a few minutes.

Blogpost ticket (internal): https://github.com/microsoft/dotnet-blog/issues/1913

Code should be

Contoso.Tests.fsproj:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>

    <EnableExpectoTestingPlatformIntegration>true</EnableExpectoTestingPlatformIntegration>
    <OutputType>Exe</OutputType>
    <TestingPlatformDotnetTestSupport>true</TestingPlatformDotnetTestSupport>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="YoloDev.Expecto.TestSdk" Version="0.15.2" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Contoso\Contoso.csproj" />
  </ItemGroup>

  <ItemGroup>
    <Compile Include="Test.fs" />
  </ItemGroup>

</Project>

Test.fs:

module Contoso.Tests

open Expecto

[<Tests>]
let tests =
    testList "Calculator Tests" [
        test "Add function returns sum" {
            let calculator = Calculator()
            let result = calculator.Add(1, 2)
            Expect.equal result 3 "Expected sum to be 3"
        }
    ]

PS: If you want to go with your own main, you will need to set GenerateTestingPlatformEntryPoint MSBuild property to false. Let me check with @Alxandr where he would prefer to have some examples.

[Alxandr]

It would probably be a reasonable idea to add an examples folder at the root of the expecto.testsdk project. Though, I would want to add it to CI (same as the test folder).

[marcingolenia]

Thanks guys! Indeed removing the [<EntryPoint>] along with main function fixes this. Thank you for updating the blog post.

Rider still doesn't detect the tests but I guess this waits for JetBrains to deal with https://youtrack.jetbrains.com/issue/RIDER-7172/Support-Expecto-test-framework.

Regarding the GenerateTestingPlatformEntryPoint it looks it doesn't change the situation when I want to have my own main, which can be handy for running TestContainers stuff for example. So the fsproj;

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <TargetFramework>net9.0</TargetFramework>
        <EnableExpectoTestingPlatformIntegration>true</EnableExpectoTestingPlatformIntegration>
        <OutputType>Exe</OutputType>
        <TestingPlatformDotnetTestSupport>true</TestingPlatformDotnetTestSupport>
        <GenerateTestingPlatformEntryPoint>false</GenerateTestingPlatformEntryPoint>
    </PropertyGroup>
    <ItemGroup>
        <PackageReference Include="YoloDev.Expecto.TestSdk" Version="0.15.2" />
    </ItemGroup>
    <ItemGroup>
        <Compile Include="Program.fs" />
    </ItemGroup>
</Project>

error:

Any hints?

[nohwnd]

You need:

		<GenerateTestingPlatformEntryPoint>false</GenerateTestingPlatformEntryPoint>
		<GenerateSelfRegisteredExtensions>false</GenerateSelfRegisteredExtensions>

[nohwnd]

Still the selfregistered extension should move up, because IMHO it is split to two options so you can take advantage of the self registered extensions while writing your own main.

[nohwnd]

Same remark on order is here: #5095

[nohwnd]

This is what XUnit does, to generate their own entrypoint and support self registered extensions as well:

https://grep.app/search?f.repo.pattern=xunit&q=selfregist

And this note on what to do if custom entrypoint with this is needed.

https://github.com/microsoft/testfx/pull/5095/files#diff-5d3ae7e6473cfc94d5588142ee5142dfe9d6c0850ccbc274e3e053885e0e3163R161-R162

[Youssef1313]

<Compile Include="Program.fs" /> needs to be <CompileAfter Include="Program.fs" />.

F# tooling will then ensure Program.fs is the ordered later.

https://github.com/dotnet/fsharp/blob/05500b8b5d64b324c57a28b9b991ede079df03f4/src/FSharp.Build/Microsoft.FSharp.Targets#L258-L277

@marcingolenia Does this address the issue you encountered?