Add FsCheck.Xunit.TestOutputRunner.

src/FsCheck.Xunit/FsCheck.Xunit.fsproj

@@ -8,6 +8,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="AssemblyInfo.fs" />
+    <Compile Include="Runner.fs" />
     <Compile Include="PropertyAttribute.fs" />
     <Compile Include="CheckExtensions.fs" />
   </ItemGroup>

src/FsCheck.Xunit/PropertyAttribute.fs

@@ -4,11 +4,12 @@ open System
 open System.Reflection
 open System.Threading.Tasks
 
-open FsCheck
 open Xunit
 open Xunit.Sdk
 open Xunit.Abstractions
 
+open FsCheck
+
 type PropertyFailedException =
     inherit Exception
     new (testResult:FsCheck.TestResult) = {

src/FsCheck.Xunit/Runner.fs

@@ -0,0 +1,20 @@
+namespace FsCheck.Xunit
+
+open FsCheck
+
+/// A runner for FsCheck (i.e. that you can use as Config.Runner) which outputs
+/// to Xunit's given ITestOutputHelper.
+/// For example, { Config.QuickThrowOnFailure with Runner = TestOutputRunner(output) }
+type TestOutputRunner(output: Xunit.Abstractions.ITestOutputHelper) =
+    interface IRunner with
+        member _.OnStartFixture t =
+            output.WriteLine (Runner.onStartFixtureToString t)
+        member _.OnArguments (ntest, args, every) =
+            output.WriteLine (every ntest args)
+        member _.OnShrink(args, everyShrink) =
+            output.WriteLine (everyShrink args)
+        member _.OnFinished(name,testResult) =
+            let resultText = Runner.onFinishedToString name testResult
+            match testResult with
+            | TestResult.True _ -> resultText |> output.WriteLine
+            | _ -> failwithf "%s" resultText