Add ScribanRegistrationCallback to register custom Scriban functions (#1515) (#1516)

- Add WireMockServerSettings.ScribanRegistrationCallback
  (Action<object, IFileSystemHandler>?) so code-configured servers can add
  functions, objects or variables to Scriban and Scriban-DotLiquid templates.
- Pass the settings to ScribanContextFactory, which invokes the callback with
  a new ScriptObject per transformer context.
- Push the custom globals beneath the template model in ScribanContext so
  request, response, mapping and data take precedence; keep the original
  Template.Render call when no callback is configured.
- Add the strongly typed WithScribanRegistration extension method.
- Add a Scriban example to the .NET 8 console app.
- Make the proxy tests use a local target server instead of www.google.com,
  and skip the IPv6 loopback test when the OS has no IPv6 support.

Co-authored-by: Mattias <13809209+Quattordici@users.noreply.github.com>

examples/WireMock.Net.Console.NET8/MainApp.cs

@@ -3,6 +3,7 @@
 using System.Globalization;
 using System.Net;
 using Newtonsoft.Json;
+using Scriban.Runtime;
 using WireMock.Logging;
 using WireMock.Matchers;
 using WireMock.Models;
@@ -409,12 +410,26 @@ namespace WireMock.Net.ConsoleApplication
                     // handlebarsContext.RegisterHelper(transformer.Name, transformer.Render); TODO
                 },
 
+                ScribanRegistrationCallback = (scriptObject, fileSystemHandler) =>
+                {
+                    var globals = (ScriptObject)scriptObject;
+                    globals.Import("greet", new Func<string, string>(name => $"Hello {name}"));
+                },
+
                 // Uncomment below if you want to use the CustomFileSystemFileHandler
                 // FileSystemHandler = new CustomFileSystemFileHandler()
             });
             System.Console.WriteLine("WireMockServer listening at {0}", string.Join(",", server.Urls));
 
             server.SetBasicAuthentication("a", "b");
+
+            server
+                .Given(Request.Create().WithPath("/scriban/greet").UsingGet())
+                .RespondWith(Response.Create()
+                    .WithBody("{{ greet 'WireMock.Net' }}")
+                    .WithTransformer(TransformerType.Scriban)
+                );
+
             //server.SetAzureADAuthentication(Environment.GetEnvironmentVariable("WIREMOCK_AAD_TENANT")!, "api://e083d51a-01a6-446c-8ad5-0c5c7f002208");
 
             //var http = new HttpClient();

src/WireMock.Net.Minimal/Settings/WireMockServerSettingsExtensions.cs

@@ -0,0 +1,40 @@
+// Copyright © WireMock.Net
+
+using JetBrains.Annotations;
+using Scriban.Runtime;
+using Stef.Validation;
+using WireMock.Handlers;
+
+namespace WireMock.Settings;
+
+/// <summary>
+/// Extension methods for <see cref="WireMockServerSettings"/>.
+/// </summary>
+public static class WireMockServerSettingsExtensions
+{
+    /// <summary>
+    /// Adds a strongly typed Scriban registration to <see cref="WireMockServerSettings.ScribanRegistrationCallback"/>.
+    /// </summary>
+    /// <remarks>
+    /// Members added to the <see cref="ScriptObject"/> are available as globals in Scriban and Scriban-DotLiquid templates.
+    /// When a callback is already configured, it is kept and invoked before <paramref name="registrationCallback"/>.
+    /// </remarks>
+    /// <param name="settings">The settings.</param>
+    /// <param name="registrationCallback">The action which registers functions, objects or variables on the <see cref="ScriptObject"/>.</param>
+    /// <returns>The same <see cref="WireMockServerSettings"/> instance.</returns>
+    [PublicAPI]
+    public static WireMockServerSettings WithScribanRegistration(this WireMockServerSettings settings, Action<ScriptObject, IFileSystemHandler> registrationCallback)
+    {
+        Guard.NotNull(settings);
+        Guard.NotNull(registrationCallback);
+
+        var existingCallback = settings.ScribanRegistrationCallback;
+        settings.ScribanRegistrationCallback = (scriptObject, fileSystemHandler) =>
+        {
+            existingCallback?.Invoke(scriptObject, fileSystemHandler);
+            registrationCallback((ScriptObject)scriptObject, fileSystemHandler);
+        };
+
+        return settings;
+    }
+}

src/WireMock.Net.Minimal/Transformers/Scriban/ScribanContext.cs

@@ -1,6 +1,7 @@
 // Copyright © WireMock.Net
 
 using Scriban;
+using Scriban.Runtime;
 using Stef.Validation;
 using WireMock.Handlers;
 using WireMock.Types;
@@ -9,21 +10,40 @@ namespace WireMock.Transformers.Scriban;
 
 internal class ScribanContext : ITransformerContext
 {
+    private static readonly MemberRenamerDelegate MemberRenamer = member => member.Name;
+
     private readonly TransformerType _transformerType;
+    private readonly ScriptObject? _customGlobals;
 
     public IFileSystemHandler FileSystemHandler { get; }
 
-    public ScribanContext(IFileSystemHandler fileSystemHandler, TransformerType transformerType)
+    public ScribanContext(IFileSystemHandler fileSystemHandler, TransformerType transformerType, ScriptObject? customGlobals = null)
     {
         FileSystemHandler = Guard.NotNull(fileSystemHandler);
         _transformerType = transformerType;
+        _customGlobals = customGlobals;
     }
 
     public string ParseAndRender(string text, object model)
     {
-        var template = _transformerType == TransformerType.ScribanDotLiquid ? Template.ParseLiquid(text) : Template.Parse(text);
+        var isLiquid = _transformerType == TransformerType.ScribanDotLiquid;
+        var template = isLiquid ? Template.ParseLiquid(text) : Template.Parse(text);
 
-        return template.Render(model, member => member.Name);
+        if (_customGlobals is null)
+        {
+            return template.Render(model, MemberRenamer);
+        }
+
+        // Same as Template.Render(model, MemberRenamer), but with the custom globals pushed beneath the model so that the model takes precedence.
+        var context = isLiquid ? new LiquidTemplateContext() : new TemplateContext();
+        context.MemberRenamer = MemberRenamer;
+        context.PushGlobal(_customGlobals);
+
+        var modelGlobals = new ScriptObject();
+        modelGlobals.Import(model, renamer: MemberRenamer);
+        context.PushGlobal(modelGlobals);
+
+        return template.Render(context);
     }
 
     public object? ParseAndEvaluate(string text, object model)

src/WireMock.Net.Minimal/Transformers/Scriban/ScribanContextFactory.cs

@@ -1,24 +1,32 @@
 // Copyright © WireMock.Net
 
-using WireMock.Handlers;
+using Scriban.Runtime;
-using WireMock.Types;
 using Stef.Validation;
+using WireMock.Settings;
+using WireMock.Types;
 
 namespace WireMock.Transformers.Scriban;
 
 internal class ScribanContextFactory : ITransformerContextFactory
 {
-    private readonly IFileSystemHandler _fileSystemHandler;
+    private readonly WireMockServerSettings _settings;
     private readonly TransformerType _transformerType;
 
-    public ScribanContextFactory(IFileSystemHandler fileSystemHandler, TransformerType transformerType)
+    public ScribanContextFactory(WireMockServerSettings settings, TransformerType transformerType)
     {
-        _fileSystemHandler = Guard.NotNull(fileSystemHandler);
+        _settings = Guard.NotNull(settings);
         _transformerType = Guard.Condition(transformerType, t => t is TransformerType.Scriban or TransformerType.ScribanDotLiquid);
     }
 
     public ITransformerContext Create()
     {
-        return new ScribanContext(_fileSystemHandler, _transformerType);
+        ScriptObject? customGlobals = null;
+        if (_settings.ScribanRegistrationCallback is { } registrationCallback)
+        {
+            customGlobals = new ScriptObject();
+            registrationCallback(customGlobals, _settings.FileSystemHandler);
+        }
+
+        return new ScribanContext(_settings.FileSystemHandler, _transformerType, customGlobals);
     }
 }

src/WireMock.Net.Minimal/Transformers/TransformerFactory.cs

@@ -19,8 +19,8 @@ internal static class TransformerFactory
                 
             case TransformerType.Scriban:
             case TransformerType.ScribanDotLiquid:
-                var factoryDotLiquid = new ScribanContextFactory(settings.FileSystemHandler, transformerType);
+                var factoryScriban = new ScribanContextFactory(settings, transformerType);
-                return new Transformer(settings, factoryDotLiquid);
+                return new Transformer(settings, factoryScriban);
 
             default:
                 throw new NotSupportedException($"{nameof(TransformerType)} '{transformerType}' is not supported.");

src/WireMock.Net.Shared/Settings/WireMockServerSettings.cs

@@ -194,6 +194,20 @@ public class WireMockServerSettings
     [JsonIgnore]
     public Action<IHandlebars, IFileSystemHandler>? HandlebarsRegistrationCallback { get; set; }
 
+    /// <summary>
+    /// Action which can be used to add additional Scriban registrations (functions, objects or variables). [Optional]
+    /// </summary>
+    /// <remarks>
+    /// The first argument is a <c>Scriban.Runtime.ScriptObject</c> from the <c>Scriban.Signed</c> package.
+    /// It is typed as <see cref="object"/> so that this package does not depend on Scriban.
+    /// Members added to it are available as globals in <see cref="TransformerType.Scriban"/> and <see cref="TransformerType.ScribanDotLiquid"/> templates.
+    /// On a name clash the template model (<c>request</c>, <c>response</c>, <c>mapping</c> and <c>data</c>) takes precedence.
+    /// The action is invoked each time a transformer context is created.
+    /// </remarks>
+    [PublicAPI]
+    [JsonIgnore]
+    public Action<object, IFileSystemHandler>? ScribanRegistrationCallback { get; set; }
+
     /// <summary>
     /// Allow the usage of CSharpCodeMatcher (default is not allowed).
     /// </summary>

test/WireMock.Net.Tests/ResponseBuilders/ResponseWithScribanTests.cs

@@ -8,6 +8,8 @@ using WireMock.Util;
 using WireMock.Handlers;
 using Moq;
 using Microsoft.AspNetCore.Http;
+using Newtonsoft.Json;
+using Scriban.Runtime;
 
 namespace WireMock.Net.Tests.ResponseBuilders;
 
@@ -65,5 +67,50 @@ public class ResponseWithScribanTests
         // Assert
         response.Message.BodyData.BodyAsString.Should().Be("test http://localhost/foo /foo POSt");
     }
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public async Task Response_ProvideResponse_WithScribanRegistrationCallback_UsesCustomFunctionInBodyAndHeaders(TransformerType transformerType)
+    {
+        // Arrange
+        _settings.ScribanRegistrationCallback = (scriptObject, _) =>
+            ((ScriptObject)scriptObject).Import("fake_name", new Func<string>(() => "Jane Doe"));
+
+        var request = new RequestMessage(new UrlDetails("http://localhost/foo"), "GET", ClientIp);
+
+        var responseBuilder = Response.Create()
+            .WithBody("{{ fake_name }} {{ request.Path }}")
+            .WithHeader("x-name", "{{ fake_name }}")
+            .WithTransformer(transformerType);
+
+        // Act
+        var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, Mock.Of<HttpContext>(), request, _settings);
+
+        // Assert
+        response.Message.BodyData!.BodyAsString.Should().Be("Jane Doe /foo");
+        response.Message.Headers!["x-name"].Should().ContainSingle().Which.Should().Be("Jane Doe");
+    }
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public async Task Response_ProvideResponse_WithScribanRegistrationCallback_UsesCustomFunctionInBodyAsJson(TransformerType transformerType)
+    {
+        // Arrange
+        _settings.WithScribanRegistration((scriptObject, _) => scriptObject.Import("fake_name", new Func<string>(() => "Jane Doe")));
+
+        var request = new RequestMessage(new UrlDetails("http://localhost/foo"), "GET", ClientIp);
+
+        var responseBuilder = Response.Create()
+            .WithBodyAsJson(new { name = "{{ fake_name }}", path = "{{ request.Path }}" })
+            .WithTransformer(transformerType);
+
+        // Act
+        var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, Mock.Of<HttpContext>(), request, _settings);
+
+        // Assert
+        JsonConvert.SerializeObject(response.Message.BodyData!.BodyAsJson).Should().Be("{\"name\":\"Jane Doe\",\"path\":\"/foo\"}");
+    }
 }
 

test/WireMock.Net.Tests/Settings/WireMockServerSettingsExtensionsTests.cs

@@ -0,0 +1,82 @@
+// Copyright © WireMock.Net
+
+using Moq;
+using Scriban.Runtime;
+using WireMock.Handlers;
+using WireMock.Settings;
+
+namespace WireMock.Net.Tests.Settings;
+
+public class WireMockServerSettingsExtensionsTests
+{
+    private readonly IFileSystemHandler _fileSystemHandler = Mock.Of<IFileSystemHandler>();
+
+    [Fact]
+    public void WithScribanRegistration_SetsCallbackWhichPassesTypedScriptObjectAndFileSystemHandler()
+    {
+        // Arrange
+        ScriptObject? receivedScriptObject = null;
+        IFileSystemHandler? receivedFileSystemHandler = null;
+        var settings = new WireMockServerSettings();
+        var scriptObject = new ScriptObject();
+
+        // Act
+        var result = settings.WithScribanRegistration((so, fs) =>
+        {
+            receivedScriptObject = so;
+            receivedFileSystemHandler = fs;
+        });
+        settings.ScribanRegistrationCallback!(scriptObject, _fileSystemHandler);
+
+        // Assert
+        result.Should().BeSameAs(settings);
+        receivedScriptObject.Should().BeSameAs(scriptObject);
+        receivedFileSystemHandler.Should().BeSameAs(_fileSystemHandler);
+    }
+
+    [Fact]
+    public void WithScribanRegistration_WithExistingCallback_InvokesBothInRegistrationOrder()
+    {
+        // Arrange
+        var calls = new List<string>();
+        var settings = new WireMockServerSettings
+        {
+            ScribanRegistrationCallback = (_, _) => calls.Add("existing")
+        };
+
+        // Act
+        settings
+            .WithScribanRegistration((_, _) => calls.Add("first"))
+            .WithScribanRegistration((_, _) => calls.Add("second"));
+        settings.ScribanRegistrationCallback!(new ScriptObject(), _fileSystemHandler);
+
+        // Assert
+        calls.Should().Equal("existing", "first", "second");
+    }
+
+    [Fact]
+    public void WithScribanRegistration_WithNullSettings_ThrowsArgumentNullException()
+    {
+        // Arrange
+        WireMockServerSettings settings = null!;
+
+        // Act
+        Action act = () => settings.WithScribanRegistration((_, _) => { });
+
+        // Assert
+        act.Should().Throw<ArgumentNullException>();
+    }
+
+    [Fact]
+    public void WithScribanRegistration_WithNullCallback_ThrowsArgumentNullException()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings();
+
+        // Act
+        Action act = () => settings.WithScribanRegistration(null!);
+
+        // Assert
+        act.Should().Throw<ArgumentNullException>();
+    }
+}

test/WireMock.Net.Tests/Transformers/Scriban/ScribanContextFactoryTests.cs

@@ -1,7 +1,9 @@
 // Copyright © WireMock.Net
 
 using Moq;
+using Scriban.Runtime;
 using WireMock.Handlers;
+using WireMock.Settings;
 using WireMock.Transformers.Scriban;
 using WireMock.Types;
 
@@ -17,23 +19,79 @@ namespace WireMock.Net.Tests.Transformers.Scriban
         public void Create_With_Scriban_TransformerType_Creates_ITransformerContext(TransformerType transformerType)
         {
             // Arrange
-            var sut = new ScribanContextFactory(_fileSystemHandlerMock.Object, transformerType);
+            var settings = new WireMockServerSettings
+            {
+                FileSystemHandler = _fileSystemHandlerMock.Object
+            };
+            var sut = new ScribanContextFactory(settings, transformerType);
 
             // Act
             var result = sut.Create();
 
             // Assert
             result.Should().NotBeNull();
+            result.FileSystemHandler.Should().BeSameAs(_fileSystemHandlerMock.Object);
         }
 
         [Fact]
         public void Create_With_Invalid_TransformerType_Throws_Exception()
         {
+            // Arrange
+            var settings = new WireMockServerSettings
+            {
+                FileSystemHandler = _fileSystemHandlerMock.Object
+            };
+
             // Act
-            Action action = () => new ScribanContextFactory(_fileSystemHandlerMock.Object, TransformerType.Handlebars);
+            Action action = () => new ScribanContextFactory(settings, TransformerType.Handlebars);
 
             // Assert
             action.Should().Throw<Exception>();
         }
+
+        [Theory]
+        [InlineData(TransformerType.Scriban)]
+        [InlineData(TransformerType.ScribanDotLiquid)]
+        public void Create_WithScribanRegistrationCallback_InvokesCallbackOnceWithScriptObjectAndFileSystemHandler(TransformerType transformerType)
+        {
+            // Arrange
+            var calls = new List<(object ScriptObject, IFileSystemHandler FileSystemHandler)>();
+            var settings = new WireMockServerSettings
+            {
+                FileSystemHandler = _fileSystemHandlerMock.Object,
+                ScribanRegistrationCallback = (scriptObject, fileSystemHandler) => calls.Add((scriptObject, fileSystemHandler))
+            };
+            var sut = new ScribanContextFactory(settings, transformerType);
+
+            // Act
+            var result = sut.Create();
+
+            // Assert
+            result.Should().NotBeNull();
+            calls.Should().ContainSingle();
+            calls[0].ScriptObject.Should().BeOfType<ScriptObject>();
+            calls[0].FileSystemHandler.Should().BeSameAs(_fileSystemHandlerMock.Object);
+        }
+
+        [Fact]
+        public void Create_CalledTwice_InvokesScribanRegistrationCallbackWithNewScriptObjectEachTime()
+        {
+            // Arrange
+            var scriptObjects = new List<object>();
+            var settings = new WireMockServerSettings
+            {
+                FileSystemHandler = _fileSystemHandlerMock.Object,
+                ScribanRegistrationCallback = (scriptObject, _) => scriptObjects.Add(scriptObject)
+            };
+            var sut = new ScribanContextFactory(settings, TransformerType.Scriban);
+
+            // Act
+            sut.Create();
+            sut.Create();
+
+            // Assert
+            scriptObjects.Should().HaveCount(2);
+            scriptObjects[0].Should().NotBeSameAs(scriptObjects[1]);
+        }
     }
-}
+}␍

test/WireMock.Net.Tests/Transformers/Scriban/ScribanContextTests.cs

@@ -0,0 +1,165 @@
+// Copyright © WireMock.Net
+
+using Moq;
+using Scriban.Runtime;
+using WireMock.Handlers;
+using WireMock.Models;
+using WireMock.Transformers;
+using WireMock.Transformers.Scriban;
+using WireMock.Types;
+using WireMock.Util;
+
+namespace WireMock.Net.Tests.Transformers.Scriban;
+
+public class ScribanContextTests
+{
+    private readonly IFileSystemHandler _fileSystemHandler = Mock.Of<IFileSystemHandler>();
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public void ParseAndRender_WithCustomFunction_RendersFunctionResult(TransformerType transformerType)
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.Import("fake_name", new Func<string>(() => "Jane Doe"));
+        var sut = new ScribanContext(_fileSystemHandler, transformerType, customGlobals);
+
+        // Act
+        var result = sut.ParseAndRender("Hello {{ fake_name }} at {{ request.Path }}", CreateModel());
+
+        // Assert
+        result.Should().Be("Hello Jane Doe at /foo/bar");
+    }
+
+    [Fact]
+    public void ParseAndRender_Scriban_WithCustomFunctionWithArgument_RendersFunctionResult()
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.Import("greet", new Func<string, string>(name => $"Hello {name}"));
+        var sut = new ScribanContext(_fileSystemHandler, TransformerType.Scriban, customGlobals);
+
+        // Act
+        var result = sut.ParseAndRender("{{ greet request.Method }}", CreateModel());
+
+        // Assert
+        result.Should().Be("Hello GET");
+    }
+
+    [Fact]
+    public void ParseAndRender_ScribanDotLiquid_WithCustomFunctionAsFilter_RendersFunctionResult()
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.Import("greet", new Func<string, string>(name => $"Hello {name}"));
+        var sut = new ScribanContext(_fileSystemHandler, TransformerType.ScribanDotLiquid, customGlobals);
+
+        // Act
+        var result = sut.ParseAndRender("{{ request.Method | greet }}", CreateModel());
+
+        // Assert
+        result.Should().Be("Hello GET");
+    }
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public void ParseAndRender_WithCustomGlobalNamedLikeModelMember_ModelTakesPrecedence(TransformerType transformerType)
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.SetValue("request", "custom", false);
+        customGlobals.SetValue("other", "custom", false);
+        var sut = new ScribanContext(_fileSystemHandler, transformerType, customGlobals);
+
+        // Act
+        var result = sut.ParseAndRender("{{ request.Path }} {{ other }}", CreateModel());
+
+        // Assert
+        result.Should().Be("/foo/bar custom");
+    }
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public void ParseAndRender_WithCustomGlobalNamedLikeBuiltin_CustomGlobalTakesPrecedence(TransformerType transformerType)
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.SetValue("date", "custom date", false);
+        var sut = new ScribanContext(_fileSystemHandler, transformerType, customGlobals);
+
+        // Act
+        var result = sut.ParseAndRender("{{ date }}", CreateModel());
+
+        // Assert
+        result.Should().Be("custom date");
+    }
+
+    [Fact]
+    public void ParseAndRender_WithTemplateAssignment_DoesNotMutateCustomGlobals()
+    {
+        // Arrange
+        var customGlobals = new ScriptObject();
+        customGlobals.SetValue("x", "custom", false);
+        var sut = new ScribanContext(_fileSystemHandler, TransformerType.Scriban, customGlobals);
+
+        // Act
+        var first = sut.ParseAndRender("{{ x = 'assigned'; x }} {{ y = 1; y }}", CreateModel());
+        var second = sut.ParseAndRender("{{ x }}", CreateModel());
+
+        // Assert
+        first.Should().Be("assigned 1");
+        second.Should().Be("custom");
+        customGlobals.Keys.Should().BeEquivalentTo("x");
+        customGlobals["x"].Should().Be("custom");
+    }
+
+    [Theory]
+    [InlineData(TransformerType.Scriban, "{{ request.Url }} {{ request.Path }} {{ request.Method }}")]
+    [InlineData(TransformerType.Scriban, "{{ request.PathSegments[1] }} {{ request.Headers.Accept }}")]
+    [InlineData(TransformerType.Scriban, "{{ for s in request.PathSegments }}[{{ s }}]{{ end }}")]
+    [InlineData(TransformerType.Scriban, "{{ request.Body | string.upcase }} {{ data.Id }}")]
+    [InlineData(TransformerType.Scriban, "{{ x = 5; x * 2 }}")]
+    [InlineData(TransformerType.ScribanDotLiquid, "{{ request.Url }} {{ request.Path }} {{ request.Method }}")]
+    [InlineData(TransformerType.ScribanDotLiquid, "{% for s in request.PathSegments %}[{{ s }}]{% endfor %}")]
+    [InlineData(TransformerType.ScribanDotLiquid, "{{ request.Body | upcase }} {{ data.Id }}")]
+    [InlineData(TransformerType.ScribanDotLiquid, "{% assign x = 5 %}{{ x | times: 2 }}")]
+    public void ParseAndRender_WithEmptyCustomGlobals_RendersSameAsWithoutCustomGlobals(TransformerType transformerType, string template)
+    {
+        // Arrange
+        var model = CreateModel();
+        var withoutCustomGlobals = new ScribanContext(_fileSystemHandler, transformerType);
+        var withCustomGlobals = new ScribanContext(_fileSystemHandler, transformerType, new ScriptObject());
+
+        // Act
+        var expected = withoutCustomGlobals.ParseAndRender(template, model);
+        var result = withCustomGlobals.ParseAndRender(template, model);
+
+        // Assert
+        expected.Should().NotBeNullOrWhiteSpace();
+        result.Should().Be(expected);
+    }
+
+    private static TransformModel CreateModel()
+    {
+        var body = new BodyData
+        {
+            BodyAsString = "hello",
+            DetectedBodyType = BodyType.String
+        };
+        var headers = new Dictionary<string, string[]>
+        {
+            { "Accept", ["application/json"] }
+        };
+        var request = new RequestMessage(new UrlDetails("http://localhost/foo/bar"), "GET", "::1", body, headers);
+
+        return new TransformModel
+        {
+            mapping = Mock.Of<IMapping>(),
+            request = request,
+            data = new { Id = 42 }
+        };
+    }
+}

test/WireMock.Net.Tests/WireMockServer.Proxy.cs

@@ -59,12 +59,13 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_AdminFalse_With_SaveMapping_Is_True_And_SaveMappingToFile_Is_False_Should_AddInternalMappingOnly()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var cancellationToken = TestContext.Current.CancellationToken;
         var settings = new WireMockServerSettings
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = true,
                 SaveMappingToFile = false,
                 ExcludedHeaders = ["Connection"] // Needed for .NET 4.5.x and 4.6.x
@@ -93,12 +94,13 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_AdminTrue_With_SaveMapping_Is_True_And_SaveMappingToFile_Is_False_Should_AddInternalMappingOnly()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var cancellationToken = TestContext.Current.CancellationToken;
         var settings = new WireMockServerSettings
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = true,
                 SaveMappingToFile = false,
                 ExcludedHeaders = ["Connection"] // Needed for .NET 4.5.x and 4.6.x
@@ -185,6 +187,7 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_With_SaveMapping_Is_False_And_SaveMappingToFile_Is_True_ShouldSaveMappingToFile()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var fileSystemHandlerMock = new Mock<IFileSystemHandler>();
         fileSystemHandlerMock.Setup(f => f.GetMappingFolder()).Returns("m");
 
@@ -192,7 +195,7 @@ public class WireMockServerProxyTests
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = false,
                 SaveMappingToFile = true
             },
@@ -221,6 +224,7 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_With_SaveMappingForStatusCodePattern_Is_False_Should_Not_SaveMapping()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var fileSystemHandlerMock = new Mock<IFileSystemHandler>();
         fileSystemHandlerMock.Setup(f => f.GetMappingFolder()).Returns("m");
 
@@ -228,7 +232,7 @@ public class WireMockServerProxyTests
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = true,
                 SaveMappingToFile = true,
                 SaveMappingForStatusCodePattern = "999" // Just make sure that we don't want this mapping
@@ -258,6 +262,7 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_With_DoNotSaveMappingForHttpMethod_Should_Not_SaveMapping()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var fileSystemHandlerMock = new Mock<IFileSystemHandler>();
         fileSystemHandlerMock.Setup(f => f.GetMappingFolder()).Returns("m");
 
@@ -265,7 +270,7 @@ public class WireMockServerProxyTests
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = true,
                 SaveMappingToFile = true,
                 SaveMappingSettings = new ProxySaveMappingSettings
@@ -298,11 +303,12 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_Should_log_proxied_requests()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var settings = new WireMockServerSettings
         {
             ProxyAndRecordSettings = new ProxyAndRecordSettings
             {
-                Url = "http://www.google.com",
+                Url = target.Url!,
                 SaveMapping = true,
                 SaveMappingToFile = false
             }
@@ -328,12 +334,13 @@ public class WireMockServerProxyTests
     public async Task WireMockServer_Proxy_Should_proxy_responses()
     {
         // Assign
+        using var target = StartProxyTargetServer();
         var cancellationToken = TestContext.Current.CancellationToken;
         string path = $"/prx_{Guid.NewGuid()}";
         var server = WireMockServer.Start();
         server
             .Given(Request.Create().WithPath(path))
-            .RespondWith(Response.Create().WithProxy("http://www.google.com"));
+            .RespondWith(Response.Create().WithProxy(target.Url!));
 
         // Act
         var requestMessage = new HttpRequestMessage
@@ -349,7 +356,7 @@ public class WireMockServerProxyTests
         // Assert
         server.Mappings.Should().HaveCount(1);
         server.LogEntries.Should().HaveCount(1);
-        content.Should().Contain("google");
+        content.Should().Be(ProxyTargetBody);
 
         server.Stop();
     }
@@ -947,6 +954,20 @@ public class WireMockServerProxyTests
         server.LogEntries.Should().HaveCount(1);
         server.Stop();
     }
+
+    private const string ProxyTargetBody = "response from proxy target";
+
+    private static WireMockServer StartProxyTargetServer()
+    {
+        var target = WireMockServer.Start();
+        target
+            .Given(Request.Create().WithPath("/*"))
+            .RespondWith(Response.Create()
+                .WithStatusCode(HttpStatusCode.OK)
+                .WithBody(ProxyTargetBody));
+
+        return target;
+    }
 }
 
 

test/WireMock.Net.Tests/WireMockServer.Settings.cs

@@ -1,13 +1,18 @@
 // Copyright © WireMock.Net
 
+using System.Net.Http;
 using Moq;
 
+using Scriban.Runtime;
 using WireMock.Authentication;
 using WireMock.Constants;
 using WireMock.Logging;
 using WireMock.Owin;
+using WireMock.RequestBuilders;
+using WireMock.ResponseBuilders;
 using WireMock.Server;
 using WireMock.Settings;
+using WireMock.Types;
 
 namespace WireMock.Net.Tests;
 
@@ -228,5 +233,33 @@ public class WireMockServerSettingsTests
         options.ActivityTracingOptions.Should().BeNull();
     }
 #endif
+
+    [Theory]
+    [InlineData(TransformerType.Scriban)]
+    [InlineData(TransformerType.ScribanDotLiquid)]
+    public async Task WireMockServer_WireMockServerSettings_ScribanRegistrationCallback_IsUsedInResponseTemplate(TransformerType transformerType)
+    {
+        // Arrange
+        var cancellationToken = TestContext.Current.CancellationToken;
+        var path = $"/scriban_{Guid.NewGuid()}";
+        using var server = WireMockServer.Start(new WireMockServerSettings
+        {
+            ScribanRegistrationCallback = (scriptObject, _) =>
+                ((ScriptObject)scriptObject).Import("fake_name", new Func<string>(() => "Jane Doe"))
+        });
+
+        server
+            .Given(Request.Create().WithPath(path).UsingGet())
+            .RespondWith(Response.Create()
+                .WithBody("{{ fake_name }} {{ request.Path }}")
+                .WithTransformer(transformerType)
+            );
+
+        // Act
+        var response = await new HttpClient().GetStringAsync(server.Url + path, cancellationToken);
+
+        // Assert
+        response.Should().Be($"Jane Doe {path}");
+    }
 }
 

test/WireMock.Net.Tests/WireMockServerTests.cs

@@ -640,6 +640,8 @@ public partial class WireMockServerTests(ITestOutputHelper testOutputHelper)
     [Fact]
     public async Task WireMockServer_Should_respond_to_ipv6_loopback()
     {
+        Assert.SkipUnless(Socket.OSSupportsIPv6, "IPv6 is not supported on this machine.");
+
         // Assign
         var server = WireMockServer.Start();