Permit async ParallelQueue (#279)

* Bump WoofWare.Myriad.Plugins from 8.0.4 to 8.0.5

---
updated-dependencies:
- dependency-name: WoofWare.Myriad.Plugins
  dependency-version: 8.0.5
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

* Deps

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Smaug123 <3138005+Smaug123@users.noreply.github.com>

.config/dotnet-tools.json

@@ -3,13 +3,13 @@
   "isRoot": true,
   "tools": {
     "fantomas": {
-      "version": "7.0.2",
+      "version": "7.0.3",
       "commands": [
         "fantomas"
       ]
     },
     "fsharp-analyzers": {
-      "version": "0.31.0",
+      "version": "0.32.0",
       "commands": [
         "fsharp-analyzers"
       ]

Consumer/Consumer.fsproj

@@ -27,7 +27,7 @@
     </ItemGroup>
 
     <ItemGroup>
-      <PackageReference Include="FsUnit" Version="7.0.1" />
+      <PackageReference Include="FsUnit" Version="7.1.1" />
       <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1"/>
       <PackageReference Include="NUnit" Version="4.3.2"/>
       <PackageReference Include="NUnit3TestAdapter" Version="5.0.0"/>

Directory.Build.props

@@ -10,7 +10,7 @@
     <WarnOn>FS3388,FS3559</WarnOn>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Nerdbank.GitVersioning" Version="3.8.38-alpha" PrivateAssets="all"/>
+    <PackageReference Include="Nerdbank.GitVersioning" Version="3.8.38-alpha" PrivateAssets="all" />
   </ItemGroup>
   <PropertyGroup Condition="'$(GITHUB_ACTION)' != ''">
     <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>

FailingConsumer/FailingConsumer.fsproj

@@ -11,7 +11,7 @@
     </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="FsUnit" Version="7.0.1" />
+    <PackageReference Include="FsUnit" Version="7.1.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1"/>
     <PackageReference Include="NUnit" Version="4.3.2"/>
     <PackageReference Include="NUnit3TestAdapter" Version="5.0.0"/>

WoofWare.NUnitTestRunner.Lib/Context.fs

@@ -10,20 +10,14 @@ open System.Threading
 
 type internal OutputStreamId = | OutputStreamId of Guid
 
-type private ThreadAwareWriter
+type private ThreadAwareWriter (local : AsyncLocal<OutputStreamId>, underlying : Dictionary<OutputStreamId, TextWriter>)
-    (
-        local : AsyncLocal<OutputStreamId>,
-        underlying : Dictionary<OutputStreamId, TextWriter>,
-        mem : Dictionary<OutputStreamId, MemoryStream>
-    )
     =
     inherit TextWriter ()
     override _.get_Encoding () = Encoding.Default
 
     override this.Write (v : char) : unit =
-        use prev = ExecutionContext.Capture ()
+        lock
-
+            underlying
-        (fun _ ->
             (fun () ->
                 match underlying.TryGetValue local.Value with
                 | true, output -> output.Write v
@@ -31,16 +25,12 @@ type private ThreadAwareWriter
                     let wanted =
                         underlying |> Seq.map (fun (KeyValue (a, b)) -> $"%O{a}") |> String.concat "\n"
 
-                    failwith $"no such context: %O{local.Value}\nwanted:\n"
+                    failwith $"no such context: %O{local.Value}\nwanted:\n{wanted}"
             )
-            |> lock underlying
-        )
-        |> fun action -> ExecutionContext.Run (prev, action, ())
 
     override this.WriteLine (v : string) : unit =
-        use prev = ExecutionContext.Capture ()
+        lock
-
+            underlying
-        (fun _ ->
             (fun () ->
                 match underlying.TryGetValue local.Value with
                 | true, output -> output.WriteLine v
@@ -48,16 +38,13 @@ type private ThreadAwareWriter
                     let wanted =
                         underlying |> Seq.map (fun (KeyValue (a, b)) -> $"%O{a}") |> String.concat "\n"
 
-                    failwith $"no such context: %O{local.Value}\nwanted:\n"
+                    failwith $"no such context: %O{local.Value}\nwanted:\n{wanted}"
             )
-            |> lock underlying
-        )
-        |> fun action -> ExecutionContext.Run (prev, action, ())
 
 /// Wraps up the necessary context to intercept global state.
 [<NoEquality ; NoComparison>]
 type TestContexts =
-    private
+    internal
         {
             /// Accesses to this must be locked on StdOutWriters.
             StdOuts : Dictionary<OutputStreamId, MemoryStream>
@@ -77,8 +64,8 @@ type TestContexts =
         let stdoutWriters = Dictionary ()
         let stderrWriters = Dictionary ()
         let local = AsyncLocal ()
-        let stdoutWriter = new ThreadAwareWriter (local, stdoutWriters, stdouts)
+        let stdoutWriter = new ThreadAwareWriter (local, stdoutWriters)
-        let stderrWriter = new ThreadAwareWriter (local, stderrWriters, stderrs)
+        let stderrWriter = new ThreadAwareWriter (local, stderrWriters)
 
         {
             StdOuts = stdouts

WoofWare.NUnitTestRunner.Lib/Exception.fs

@@ -0,0 +1,10 @@
+namespace WoofWare.NUnitTestRunner
+
+open System.Runtime.ExceptionServices
+
+[<RequireQualifiedAccess>]
+module internal Exception =
+    let reraiseWithOriginalStackTrace<'a> (e : exn) : 'a =
+        let edi = ExceptionDispatchInfo.Capture e
+        edi.Throw ()
+        failwith "unreachable"

WoofWare.NUnitTestRunner.Lib/ParallelQueue.fs

@@ -4,16 +4,16 @@ open System
 open System.Threading
 open System.Threading.Tasks
 
-type private ThunkEvaluator<'ret> =
+type private AsyncThunkEvaluator<'ret> =
-    abstract Eval<'a> : (unit -> 'a) -> AsyncReplyChannel<'a> -> 'ret
+    abstract Eval<'a> : (unit -> Async<'a>) -> AsyncReplyChannel<Result<'a, exn>> -> 'ret
 
-type private ThunkCrate =
+type private AsyncThunkCrate =
-    abstract Apply<'ret> : ThunkEvaluator<'ret> -> 'ret
+    abstract Apply<'ret> : AsyncThunkEvaluator<'ret> -> 'ret
 
 [<RequireQualifiedAccess>]
-module private ThunkCrate =
+module private AsyncThunkCrate =
-    let make<'a> (t : unit -> 'a) (rc : AsyncReplyChannel<'a>) : ThunkCrate =
+    let make<'a> (t : unit -> Async<'a>) (rc : AsyncReplyChannel<Result<'a, exn>>) : AsyncThunkCrate =
-        { new ThunkCrate with
+        { new AsyncThunkCrate with
             member _.Apply e = e.Eval t rc
         }
 
@@ -41,7 +41,11 @@ type private MailboxMessage =
     | Quit of AsyncReplyChannel<unit>
     /// Check current state, see if we need to start more tests, etc.
     | Reconcile
-    | RunTest of within : TestFixture * Parallelizable<unit> option * test : ThunkCrate
+    | RunTestAsync of
+        within : TestFixture *
+        Parallelizable<unit> option *
+        test : AsyncThunkCrate *
+        context : ExecutionContext
     | BeginTestFixture of TestFixture * AsyncReplyChannel<TestFixtureRunningToken>
     | EndTestFixture of TestFixtureTearDownToken * AsyncReplyChannel<unit>
 
@@ -310,21 +314,31 @@ type ParallelQueue
                     rc.Reply ()
                     m.Post MailboxMessage.Reconcile
                     return! processTask (Running state) m
-            | MailboxMessage.RunTest (withinFixture, par, message) ->
+            | MailboxMessage.RunTestAsync (withinFixture, par, message, capturedContext) ->
                 let t () =
-                    { new ThunkEvaluator<_> with
+                    { new AsyncThunkEvaluator<_> with
-                        member _.Eval<'b> (t : unit -> 'b) rc =
+                        member _.Eval<'b> (t : unit -> Async<'b>) rc =
                             let tcs = TaskCompletionSource TaskCreationOptions.RunContinuationsAsynchronously
-                            use ec = ExecutionContext.Capture ()
 
                             fun () ->
                                 ExecutionContext.Run (
-                                    ec,
+                                    capturedContext,
                                     (fun _ ->
-                                        let result = t ()
+                                        async {
-                                        tcs.SetResult ()
+                                            let! result =
-                                        m.Post MailboxMessage.Reconcile
+                                                async {
-                                        rc.Reply result
+                                                    try
+                                                        let! r = t ()
+                                                        return Ok r
+                                                    with e ->
+                                                        return Error e
+                                                }
+
+                                            tcs.SetResult ()
+                                            m.Post MailboxMessage.Reconcile
+                                            rc.Reply result
+                                        }
+                                        |> Async.StartImmediate
                                     ),
                                     ()
                                 )
@@ -348,17 +362,36 @@ type ParallelQueue
     let mb = new MailboxProcessor<_> (processTask MailboxState.Idle)
     do mb.Start ()
 
+    /// Request to run the given async action, freely in parallel with other running tests.
+    /// The resulting Task will return when the action has completed.
+    member _.RunAsync<'a>
+        (TestFixtureSetupToken parent)
+        (scope : Parallelizable<unit> option)
+        (action : unit -> Async<'a>)
+        : 'a Task
+        =
+        let ec = ExecutionContext.Capture ()
+
+        task {
+            let! result =
+                (fun rc -> MailboxMessage.RunTestAsync (parent, scope, AsyncThunkCrate.make action rc, ec))
+                |> mb.PostAndAsyncReply
+                |> Async.StartAsTask
+
+            match result with
+            | Ok o -> return o
+            | Error e -> return Exception.reraiseWithOriginalStackTrace e
+        }
+
     /// Request to run the given action, freely in parallel with other running tests.
     /// The resulting Task will return when the action has completed.
-    member _.Run<'a>
+    member this.Run<'a>
-        (TestFixtureSetupToken parent)
+        (parent : TestFixtureSetupToken)
         (scope : Parallelizable<unit> option)
         (action : unit -> 'a)
         : 'a Task
         =
-        (fun rc -> MailboxMessage.RunTest (parent, scope, ThunkCrate.make action rc))
+        this.RunAsync parent scope (fun () -> async.Return (action ()))
-        |> mb.PostAndAsyncReply
-        |> Async.StartAsTask
 
     /// Declare that we wish to start the given test fixture. The resulting Task will return
     /// when you are allowed to start running tests from that fixture.
@@ -379,11 +412,22 @@ type ParallelQueue
                     | Parallelizable.Yes _ -> Parallelizable.Yes ()
                 )
 
+            let ec = ExecutionContext.Capture ()
+
             let! response =
-                (fun rc -> MailboxMessage.RunTest (parent, par, ThunkCrate.make action rc))
+                (fun rc ->
+                    MailboxMessage.RunTestAsync (
+                        parent,
+                        par,
+                        AsyncThunkCrate.make (fun () -> async.Return (action ())) rc,
+                        ec
+                    )
+                )
                 |> mb.PostAndAsyncReply
 
-            return response, TestFixtureSetupToken parent
+            match response with
+            | Ok response -> return response, TestFixtureSetupToken parent
+            | Error e -> return Exception.reraiseWithOriginalStackTrace e
         }
 
     /// Run the given one-time tear-down for the test fixture.
@@ -401,11 +445,22 @@ type ParallelQueue
                     | Parallelizable.Yes _ -> Parallelizable.Yes ()
                 )
 
+            let ec = ExecutionContext.Capture ()
+
             let! response =
-                (fun rc -> MailboxMessage.RunTest (parent, par, ThunkCrate.make action rc))
+                (fun rc ->
+                    MailboxMessage.RunTestAsync (
+                        parent,
+                        par,
+                        AsyncThunkCrate.make (fun () -> async.Return (action ())) rc,
+                        ec
+                    )
+                )
                 |> mb.PostAndAsyncReply
 
-            return response, TestFixtureTearDownToken parent
+            match response with
+            | Ok response -> return response, TestFixtureTearDownToken parent
+            | Error e -> return Exception.reraiseWithOriginalStackTrace e
         }
 
     /// Declare that we have finished submitting requests to run in the given test fixture.

WoofWare.NUnitTestRunner.Lib/SurfaceBaseline.txt

@@ -256,6 +256,7 @@ WoofWare.NUnitTestRunner.ParallelQueue inherit obj, implements IDisposable
 WoofWare.NUnitTestRunner.ParallelQueue..ctor [constructor]: (int option, WoofWare.NUnitTestRunner.AssemblyParallelScope WoofWare.NUnitTestRunner.Parallelizable option, System.Threading.CancellationToken option)
 WoofWare.NUnitTestRunner.ParallelQueue.EndTestFixture [method]: WoofWare.NUnitTestRunner.TestFixtureTearDownToken -> unit System.Threading.Tasks.Task
 WoofWare.NUnitTestRunner.ParallelQueue.Run [method]: WoofWare.NUnitTestRunner.TestFixtureSetupToken -> unit WoofWare.NUnitTestRunner.Parallelizable option -> (unit -> 'a) -> 'a System.Threading.Tasks.Task
+WoofWare.NUnitTestRunner.ParallelQueue.RunAsync [method]: WoofWare.NUnitTestRunner.TestFixtureSetupToken -> unit WoofWare.NUnitTestRunner.Parallelizable option -> (unit -> 'a Microsoft.FSharp.Control.FSharpAsync) -> 'a System.Threading.Tasks.Task
 WoofWare.NUnitTestRunner.ParallelQueue.RunTestSetup [method]: WoofWare.NUnitTestRunner.TestFixtureRunningToken -> (unit -> 'a) -> ('a * WoofWare.NUnitTestRunner.TestFixtureSetupToken) System.Threading.Tasks.Task
 WoofWare.NUnitTestRunner.ParallelQueue.RunTestTearDown [method]: WoofWare.NUnitTestRunner.TestFixtureSetupToken -> (unit -> 'a) -> ('a * WoofWare.NUnitTestRunner.TestFixtureTearDownToken) System.Threading.Tasks.Task
 WoofWare.NUnitTestRunner.ParallelQueue.StartTestFixture [method]: WoofWare.NUnitTestRunner.TestFixture -> WoofWare.NUnitTestRunner.TestFixtureRunningToken System.Threading.Tasks.Task

WoofWare.NUnitTestRunner.Lib/WoofWare.NUnitTestRunner.Lib.fsproj

@@ -14,7 +14,7 @@
       <PackageId>WoofWare.NUnitTestRunner.Lib</PackageId>
       <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
       <WarnOn>FS3559</WarnOn>
-      <WoofWareMyriadPluginVersion>8.0.4</WoofWareMyriadPluginVersion>
+      <WoofWareMyriadPluginVersion>8.0.5</WoofWareMyriadPluginVersion>
     </PropertyGroup>
 
     <ItemGroup>
@@ -31,6 +31,7 @@
       <Compile Include="ParallelScope.fs" />
       <Compile Include="DotnetRuntime.fs" />
       <Compile Include="Array.fs" />
+      <Compile Include="Exception.fs" />
       <Compile Include="List.fs" />
       <Compile Include="Result.fs" />
       <Compile Include="Domain.fs" />

WoofWare.NUnitTestRunner.Lib/version.json

@@ -1,5 +1,5 @@
 {
-  "version": "0.21",
+  "version": "0.22",
   "publicReleaseRefSpec": [
     "^refs/heads/main$"
   ],
@@ -8,4 +8,4 @@
     ":/Directory.Build.props",
     ":/README.md"
   ]
-}
+}

WoofWare.NUnitTestRunner/WoofWare.NUnitTestRunner.Test/TestSynchronizationContext.fs

@@ -0,0 +1,396 @@
+namespace WoofWare.NUnitTestRunner.Test
+
+open System
+open System.Text
+open System.Threading
+open System.Threading.Tasks
+open NUnit.Framework
+open FsUnitTyped
+open WoofWare.NUnitTestRunner
+
+[<TestFixture>]
+module TestSynchronizationContext =
+
+    [<Test>]
+    let ``ExecutionContext flows correctly through synchronous operations`` () =
+        task {
+            let dummyFixture =
+                TestFixture.Empty typeof<obj> (Some (Parallelizable.Yes ClassParallelScope.All)) [] []
+
+            use contexts = TestContexts.Empty ()
+            use queue = new ParallelQueue (Some 4, None)
+
+            // Track which context values we see during execution
+            let contextValues = System.Collections.Concurrent.ConcurrentBag<Guid * Guid> ()
+
+            // Start the fixture
+            let! running = queue.StartTestFixture dummyFixture
+            let! _, setup = queue.RunTestSetup running (fun () -> ())
+
+            // Create several synchronous operations with different context values
+            let tasks =
+                [ 1..10 ]
+                |> List.map (fun _ ->
+                    task {
+                        do! Task.Yield ()
+                        // Set a unique context value
+                        let outputId = contexts.NewOutputs ()
+                        let (OutputStreamId expectedId) = outputId
+                        contexts.AsyncLocal.Value <- outputId
+
+                        // Run a synchronous operation that checks the context
+                        let! actualId =
+                            queue.Run
+                                setup
+                                None
+                                (fun () ->
+                                    // Check context immediately
+                                    let immediate = contexts.AsyncLocal.Value
+                                    let (OutputStreamId immediateGuid) = immediate
+                                    contextValues.Add (expectedId, immediateGuid)
+
+                                    // Do some work that might cause context issues
+                                    Thread.Sleep 10
+
+                                    // Check context after work
+                                    let afterWork = contexts.AsyncLocal.Value
+                                    let (OutputStreamId afterWorkGuid) = afterWork
+                                    contextValues.Add (expectedId, afterWorkGuid)
+
+                                    // Simulate calling into framework code that might use ExecutionContext
+                                    let mutable capturedValue = Guid.Empty
+
+                                    ExecutionContext.Run (
+                                        ExecutionContext.Capture (),
+                                        (fun _ ->
+                                            let current = contexts.AsyncLocal.Value
+                                            let (OutputStreamId currentGuid) = current
+                                            capturedValue <- currentGuid
+                                        ),
+                                        ()
+                                    )
+
+                                    contextValues.Add (expectedId, capturedValue)
+
+                                    afterWorkGuid
+                                )
+
+                        // Verify the returned value matches what we set
+                        actualId |> shouldEqual expectedId
+                    }
+                )
+
+            // Wait for all tasks
+            let! results = Task.WhenAll tasks
+            results |> Array.iter id
+
+            // Verify all context values were correct
+            let allValues = contextValues |> Seq.toList
+            allValues |> shouldHaveLength 30 // 3 checks per operation * 10 operations
+
+            // Every captured value should match its expected value
+            allValues
+            |> List.iter (fun (expected, actual) -> actual |> shouldEqual expected)
+
+            // Clean up
+            let! _, teardown = queue.RunTestTearDown setup (fun () -> ())
+            do! queue.EndTestFixture teardown
+        }
+
+    [<Test>]
+    let ``ExecutionContext isolation between concurrent synchronous operations`` () =
+        task {
+            let dummyFixture =
+                TestFixture.Empty typeof<obj> (Some (Parallelizable.Yes ClassParallelScope.All)) [] []
+
+            use contexts = TestContexts.Empty ()
+            use queue = new ParallelQueue (Some 4, None)
+
+            let! running = queue.StartTestFixture dummyFixture
+            let! _, setup = queue.RunTestSetup running (fun () -> ())
+
+            // Use a barrier to ensure operations run concurrently
+            let barrier = new Barrier (3)
+            let seenValues = System.Collections.Concurrent.ConcurrentBag<int * Guid> ()
+            let outputIds = System.Collections.Concurrent.ConcurrentBag<OutputStreamId> ()
+
+            // Create operations that will definitely run concurrently
+            let tasks =
+                [ 1..3 ]
+                |> List.map (fun i ->
+                    task {
+                        // Each task sets its own context value
+                        let outputId = contexts.NewOutputs ()
+                        let (OutputStreamId myId) = outputId
+                        contexts.AsyncLocal.Value <- outputId
+                        outputIds.Add outputId
+
+                        let! result =
+                            queue.Run
+                                setup
+                                (Some (Parallelizable.Yes ()))
+                                (fun () ->
+                                    // Wait for all tasks to reach this point
+                                    barrier.SignalAndWait ()
+
+                                    // Now check what value we see
+                                    let currentValue = contexts.AsyncLocal.Value
+
+                                    match currentValue with
+                                    | OutputStreamId guid -> seenValues.Add (i, guid)
+
+                                    // Do some synchronous work
+                                    Thread.Sleep 5
+
+                                    // Check again after work
+                                    let afterWork = contexts.AsyncLocal.Value
+
+                                    match afterWork with
+                                    | OutputStreamId guid ->
+                                        // Also verify we can write to the correct streams
+                                        contexts.Stdout.WriteLine $"Task %i{i} sees context %O{guid}"
+                                        guid
+                                )
+
+                        // Each task should see its own value
+                        result |> shouldEqual myId
+                    }
+                )
+
+            let! results = Task.WhenAll tasks
+            results |> Array.iter id
+
+            // Verify we saw 3 different values (one per task)
+            let values = seenValues |> Seq.toList
+            values |> shouldHaveLength 3
+
+            // All seen values should be different (no context bleeding)
+            let uniqueValues = values |> List.map snd |> List.distinct
+            uniqueValues |> shouldHaveLength 3
+
+            let! _, teardown = queue.RunTestTearDown setup (fun () -> ())
+            do! queue.EndTestFixture teardown
+
+            // Verify stdout content for each task
+            let collectedOutputs = outputIds |> Seq.toList
+            collectedOutputs |> shouldHaveLength 3
+
+            for outputId in collectedOutputs do
+                let content = contexts.DumpStdout outputId
+                content |> shouldNotEqual ""
+                let (OutputStreamId guid) = outputId
+                content |> shouldContainText (guid.ToString ())
+        }
+
+    [<Test>]
+    let ``ExecutionContext flows correctly through nested synchronous operations`` () =
+        task {
+            let dummyFixture =
+                TestFixture.Empty typeof<obj> (Some (Parallelizable.Yes ClassParallelScope.All)) [] []
+
+            use contexts = TestContexts.Empty ()
+            use queue = new ParallelQueue (Some 4, None)
+
+            let! running = queue.StartTestFixture dummyFixture
+            let! _, setup = queue.RunTestSetup running (fun () -> ())
+
+            // Set an initial context
+            let outputId = contexts.NewOutputs ()
+            let (OutputStreamId outerGuid) = outputId
+            contexts.AsyncLocal.Value <- outputId
+
+            let! result =
+                queue.Run
+                    setup
+                    None
+                    (fun () ->
+                        // Check we have the outer context
+                        let outer = contexts.AsyncLocal.Value
+                        let (OutputStreamId outerSeen) = outer
+                        outerSeen |> shouldEqual outerGuid
+
+                        // Now change the context for a nested operation
+                        let innerOutputId = contexts.NewOutputs ()
+                        let (OutputStreamId innerGuid) = innerOutputId
+                        contexts.AsyncLocal.Value <- innerOutputId
+
+                        // Use Task.Run to potentially hop threads
+                        let innerResult =
+                            Task
+                                .Run(fun () ->
+                                    let inner = contexts.AsyncLocal.Value
+                                    let (OutputStreamId innerSeen) = inner
+                                    innerSeen |> shouldEqual innerGuid
+                                    innerSeen
+                                )
+                                .Result
+
+                        // After the nested operation, we should still have our inner context
+                        let afterNested = contexts.AsyncLocal.Value
+                        let (OutputStreamId afterNestedGuid) = afterNested
+                        afterNestedGuid |> shouldEqual innerGuid
+
+                        (outerSeen, innerResult, afterNestedGuid)
+                    )
+
+            // Unpack results
+            let seenOuter, seenInner, seenAfter = result
+            seenOuter |> shouldEqual outerGuid
+            seenInner |> shouldNotEqual outerGuid
+            seenAfter |> shouldEqual seenInner
+
+            let! _, teardown = queue.RunTestTearDown setup (fun () -> ())
+            do! queue.EndTestFixture teardown
+        }
+
+    [<Test>]
+    let ``ExecutionContext flows correctly through async operations`` () =
+        task {
+            // Create a test fixture
+            let dummyFixture =
+                TestFixture.Empty typeof<obj> (Some (Parallelizable.Yes ClassParallelScope.All)) [] []
+
+            use contexts = TestContexts.Empty ()
+            use queue = new ParallelQueue (Some 4, None)
+
+            // Track which context values we see during execution
+            let contextValues = System.Collections.Concurrent.ConcurrentBag<Guid * Guid> ()
+
+            // Start the fixture
+            let! running = queue.StartTestFixture dummyFixture
+            let! _, setup = queue.RunTestSetup running (fun () -> ())
+
+            // Create several async operations with different context values
+            let tasks =
+                [ 1..10 ]
+                |> List.map (fun i ->
+                    task {
+                        // Set a unique context value
+                        let expectedId = Guid.NewGuid ()
+                        let outputId = OutputStreamId expectedId
+                        contexts.AsyncLocal.Value <- outputId
+
+                        // Run an async operation that checks the context at multiple points
+                        let! actualId =
+                            queue.RunAsync
+                                setup
+                                None
+                                (fun () ->
+                                    async {
+                                        // Check context immediately
+                                        let immediate = contexts.AsyncLocal.Value
+                                        let (OutputStreamId immediateGuid) = immediate
+                                        contextValues.Add (expectedId, immediateGuid)
+
+                                        // Yield to allow potential context loss
+                                        do! Async.Sleep 10
+
+                                        // Check context after yield
+                                        let afterYield = contexts.AsyncLocal.Value
+                                        let (OutputStreamId afterYieldGuid) = afterYield
+                                        contextValues.Add (expectedId, afterYieldGuid)
+
+                                        // Do some actual async work
+                                        do! Task.Delay (10) |> Async.AwaitTask
+
+                                        // Check context after task
+                                        let afterTask = contexts.AsyncLocal.Value
+                                        let (OutputStreamId afterTaskGuid) = afterTask
+                                        contextValues.Add (expectedId, afterTaskGuid)
+
+                                        return afterTaskGuid
+                                    }
+                                )
+
+                        // Verify the returned value matches what we set
+                        actualId |> shouldEqual expectedId
+                    }
+                )
+
+            // Wait for all tasks
+            let! results = Task.WhenAll (tasks)
+            results |> Array.iter id
+
+            // Verify all context values were correct
+            let allValues = contextValues |> Seq.toList
+            allValues |> shouldHaveLength 30 // 3 checks per operation * 10 operations
+
+            // Every captured value should match its expected value
+            allValues
+            |> List.iter (fun (expected, actual) -> actual |> shouldEqual expected)
+
+            // Clean up
+            let! _, teardown = queue.RunTestTearDown setup (fun () -> ())
+            do! queue.EndTestFixture teardown
+        }
+
+    [<Test>]
+    let ``ExecutionContext isolation between concurrent operations`` () =
+        task {
+            let dummyFixture =
+                TestFixture.Empty typeof<obj> (Some (Parallelizable.Yes ClassParallelScope.All)) [] []
+
+            use contexts = TestContexts.Empty ()
+            use queue = new ParallelQueue (Some 4, None)
+
+            let! running = queue.StartTestFixture dummyFixture
+            let! _, setup = queue.RunTestSetup running (fun () -> ())
+
+            // Use a barrier to ensure operations run concurrently
+            let barrier = new Barrier (3)
+            let seenValues = System.Collections.Concurrent.ConcurrentBag<int * Guid> ()
+
+            // Create operations that will definitely run concurrently
+            let tasks =
+                [ 1..3 ]
+                |> List.map (fun i ->
+                    task {
+                        // Each task sets its own context value
+                        let myId = Guid.NewGuid ()
+                        contexts.AsyncLocal.Value <- OutputStreamId myId
+
+                        let! result =
+                            queue.RunAsync
+                                setup
+                                (Some (Parallelizable.Yes ()))
+                                (fun () ->
+                                    async {
+                                        // Wait for all tasks to reach this point
+                                        barrier.SignalAndWait () |> ignore
+
+                                        // Now check what value we see
+                                        let currentValue = contexts.AsyncLocal.Value
+
+                                        match currentValue with
+                                        | OutputStreamId guid -> seenValues.Add (i, guid)
+
+                                        // Do some async work
+                                        do! Async.Sleep 5
+
+                                        // Check again after async work
+                                        let afterAsync = contexts.AsyncLocal.Value
+
+                                        match afterAsync with
+                                        | OutputStreamId guid -> return guid
+                                    }
+                                )
+
+                        // Each task should see its own value
+                        result |> shouldEqual myId
+                    }
+                )
+
+            let! results = Task.WhenAll (tasks)
+            results |> Array.iter id
+
+            // Verify we saw 3 different values (one per task)
+            let values = seenValues |> Seq.toList
+            values |> shouldHaveLength 3
+
+            // All seen values should be different (no context bleeding)
+            let uniqueValues = values |> List.map snd |> List.distinct
+            uniqueValues |> shouldHaveLength 3
+
+            let! _, teardown = queue.RunTestTearDown setup (fun () -> ())
+            do! queue.EndTestFixture teardown
+        }

WoofWare.NUnitTestRunner/WoofWare.NUnitTestRunner.Test/WoofWare.NUnitTestRunner.Test.fsproj

@@ -11,14 +11,15 @@
         <Compile Include="TestFilter.fs" />
         <Compile Include="TestList.fs" />
         <Compile Include="TestSurface.fs" />
+        <Compile Include="TestSynchronizationContext.fs" />
         <Compile Include="TestTrx.fs" />
         <EmbeddedResource Include="Example1.trx" />
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="ApiSurface" Version="4.1.21" />
+        <PackageReference Include="ApiSurface" Version="4.1.22" />
         <PackageReference Include="FsCheck" Version="3.3.0" />
-        <PackageReference Include="FsUnit" Version="7.0.1" />
+        <PackageReference Include="FsUnit" Version="7.1.1" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
         <PackageReference Include="NUnit" Version="4.3.2" />
         <PackageReference Include="NUnit3TestAdapter" Version="5.0.0"/>

analyzers/analyzers.fsproj

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.15.0]" />
+    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.17.0]" />
   </ItemGroup>
 
 </Project>

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1750386251,
+        "lastModified": 1753432016,
-        "narHash": "sha256-1ovgdmuDYVo5OUC5NzdF+V4zx2uT8RtsgZahxidBTyw=",
+        "narHash": "sha256-cnL5WWn/xkZoyH/03NNUS7QgW5vI7D1i74g48qplCvg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "076e8c6678d8c54204abcb4b1b14c366835a58bb",
+        "rev": "6027c30c8e9810896b92429f0092f624f7b1aace",
         "type": "github"
       },
       "original": {

nix/deps.json

@@ -1,13 +1,13 @@
 [
   {
     "pname": "ApiSurface",
-    "version": "4.1.21",
+    "version": "4.1.22",
-    "hash": "sha256-v2adBYoE9NZPaQR3u2qq9r/9PxAM/wqi2Uiky0xGq+E="
+    "hash": "sha256-voj9m3YmyJ95FAMLV4sWzQMod3Em0mTjzf0LBUUFOso="
   },
   {
     "pname": "fantomas",
-    "version": "7.0.2",
+    "version": "7.0.3",
-    "hash": "sha256-BAaENIm/ksTiXrUImRgKoIXTGIlgsX7ch6ayoFjhJXA="
+    "hash": "sha256-0XlfV7SxXPDnk/CjkUesJSaH0cxlNHJ+Jj86zNUhkNA="
   },
   {
     "pname": "Fantomas.Core",
@@ -26,8 +26,8 @@
   },
   {
     "pname": "fsharp-analyzers",
-    "version": "0.31.0",
+    "version": "0.32.0",
-    "hash": "sha256-PoAvaXbXsmvVw870UsnqdD20HoBHO7u4bzoaz5DXfzM="
+    "hash": "sha256-MnhsK5tOeexL6uQhsV4nTRz8CGbz2o8VyHwAK8x91pE="
   },
   {
     "pname": "FSharp.Core",
@@ -41,8 +41,8 @@
   },
   {
     "pname": "FsUnit",
-    "version": "7.0.1",
+    "version": "7.1.1",
-    "hash": "sha256-K85CIdxMeFSHEKZk6heIXp/oFjWAn7dBILKrw49pJUY="
+    "hash": "sha256-UMCEGKxQ4ytjmPuVpiNaAPbi3RQH9gqa61JJIUS/6hg="
   },
   {
     "pname": "Microsoft.ApplicationInsights",
@@ -366,13 +366,13 @@
   },
   {
     "pname": "WoofWare.Myriad.Plugins",
-    "version": "8.0.4",
+    "version": "8.0.5",
-    "hash": "sha256-/cX7B1QDOnyYRaetl1pQRkeVNLA7vP25TJfBZhi2j/c="
+    "hash": "sha256-IfTT2GM9ktUW5BQoKQGFKK39BAKeziJJnrOIL7Vs19o="
   },
   {
     "pname": "WoofWare.Myriad.Plugins.Attributes",
-    "version": "3.6.11",
+    "version": "3.6.12",
-    "hash": "sha256-UI8wT1a3CuQUeXb1qIHCiimGJ1qBjK9ZOQN2/N5fNdg="
+    "hash": "sha256-90uiVtc5exCbkcdS8DgTmlEZZT8/AdrY0QuFzy+FHUo="
   },
   {
     "pname": "WoofWare.PrattParser",