F# Async Unit Testing

[jon49]

In the documentation it doesn't say how to test F# asynchronously with MSTest. Since F# returns Task<unit> that doesn't work and when you raise it to plain Task it ignores the test. It would be nice to know this or to know if it is not possible.

|> fun x -> Async.StartAsTask x :> Task // Doesn't work; is ignored by testing framework.

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Document Details

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• ID: 803d9667-b438-449d-db9c-f381852f6bce
• Version Independent ID: 0078395d-d69e-c773-2f01-f20956391cb1
• Content: Unit testing F# libraries in .NET Core using dotnet test and MSTest
• Content Source: docs/core/testing/unit-testing-fsharp-with-mstest.md
• Product: dotnet-core
• GitHub Login: @BillWagner
• Microsoft Alias: wiwagn

[BillWagner]

@cartermp Do you know the answer here?

[cartermp]

@jon49 can you give an example of the test you are trying to run? The approach will depend on what it is you are trying to accomplish.

That said, there are two main options available to you:

1. Use Async.RunSynchronously, which will block on the current executing thread and execute your code and await its result.
2. Use a helper such as this to extend the Async module:

module Async =
    let AwaitTaskVoid : (Task -> Async<unit>) =
        Async.AwaitIAsyncResult >> Async.Ignore

...
async { return () } |> Async.AwaitTaskVoid

[BillWagner]

@cartermp Do you want to add this info to the unit test doc we have?

[mairaw]

Ping @cartermp

[jon49]

Sorry, I haven't kept up with this. I'll see if I can get an example up for you to look at. I'll shoot for this weekend.

[mairaw]

@cartermp do you want to add that sort of info to the docs? @jon49 have you managed to get an example up?

Thanks!

[mairaw]

@cartermp what should we do about this issue?

[no-response]

This issue has been automatically closed due to no response from the original author. Please feel free to reopen it if you have more information that can help us investigate the issue further.