Add overload for plain Result case; add test handling multiple errors case

Author: tw0po1nt

src/FsToolkit.ErrorHandling/TaskValidationCE.fs

@@ -1,5 +1,6 @@
 namespace FsToolkit.ErrorHandling
 
+open System
 open System.Threading.Tasks
 open System.Runtime.CompilerServices
 open System.Threading
@@ -554,6 +555,19 @@ module TaskValidationCEExtensionsMediumPriority =
             |> Async.map Ok
             |> Async.StartImmediateAsTask
 
+        member inline _.Source(s: Async<Result<'ok, 'error>>) : TaskValidation<'ok, 'error> =
+            s
+            |> AsyncResult.mapError List.singleton
+            |> Async.StartImmediateAsTask
+
+        member inline _.Source(s: Task<Result<'ok, 'error>>) : TaskValidation<'ok, 'error> =
+            TaskResult.mapError List.singleton s
+
+        member inline _.Source(result: Result<_, _>) : Task<Validation<_, _>> =
+            result
+            |> Validation.ofResult
+            |> Task.singleton
+
 [<AutoOpen>]
 module TaskValidationCEExtensionsHighPriority2 =
 

tests/FsToolkit.ErrorHandling.TaskResult.Tests/TaskValidationCE.fs

@@ -674,6 +674,31 @@ let ``TaskValidationCE applicative tests`` =
                 Expect.equal actual (Validation.ok 6) "Should be ok"
             }
 
+        testCaseTask "Fail Path Result"
+        <| fun () ->
+            task {
+                let expected =
+                    Error [
+                        "Error 1"
+                        "Error 2"
+                    ]
+
+                let! actual =
+                    taskValidation {
+                        let! a = Ok 3
+                        and! b = Ok 2
+                        and! c = Error "Error 1"
+                        and! d = Error "Error 2"
+
+                        return
+                            a + b
+                            - c
+                            - d
+                    }
+
+                Expect.equal actual expected "Should be Error"
+            }
+
         testCaseTask "Fail Path Validation"
         <| fun () ->
             task {