Throw exception in case WithTransformer is used after WithBodyFromFile (#1185)

* Fix .WithBodyFromFile + .WithTransformer combination

* Ex

src/WireMock.Net/ResponseBuilders/Response.WithBody.cs

@@ -13,6 +13,8 @@ namespace WireMock.ResponseBuilders;
 
 public partial class Response
 {
+    private bool _bodyFromFileSet;
+
     /// <inheritdoc />
     public IResponseBuilder WithBody(Func<IRequestMessage, string> bodyFactory, string? destination = BodyDestinationFormat.SameAsSource, Encoding? encoding = null)
     {
@@ -78,6 +80,8 @@ public partial class Response
     {
         Guard.NotNull(filename);
 
+        _bodyFromFileSet = true;
+
         ResponseMessage.BodyData = new BodyData
         {
             BodyAsFileIsCached = cache,

src/WireMock.Net/ResponseBuilders/Response.WithTransformer.cs

@@ -0,0 +1,36 @@
+// Copyright © WireMock.Net
+
+using System;
+using WireMock.Types;
+
+namespace WireMock.ResponseBuilders;
+
+public partial class Response
+{
+    /// <inheritdoc cref="ITransformResponseBuilder.WithTransformer(bool)"/>
+    public IResponseBuilder WithTransformer(bool transformContentFromBodyAsFile)
+    {
+        return WithTransformer(TransformerType.Handlebars, transformContentFromBodyAsFile);
+    }
+
+    /// <inheritdoc cref="ITransformResponseBuilder.WithTransformer(ReplaceNodeOptions)"/>
+    public IResponseBuilder WithTransformer(ReplaceNodeOptions options)
+    {
+        return WithTransformer(TransformerType.Handlebars, false, options);
+    }
+
+    /// <inheritdoc />
+    public IResponseBuilder WithTransformer(TransformerType transformerType, bool transformContentFromBodyAsFile = false, ReplaceNodeOptions options = ReplaceNodeOptions.EvaluateAndTryToConvert)
+    {
+        if (_bodyFromFileSet)
+        {
+            throw new InvalidOperationException("WithTransformer should be used before WithBodyFromFile.");
+        }
+
+        UseTransformer = true;
+        TransformerType = transformerType;
+        UseTransformerForBodyAsFile = transformContentFromBodyAsFile;
+        TransformerReplaceNodeOptions = options;
+        return this;
+    }
+}

src/WireMock.Net/ResponseBuilders/Response.cs

@@ -164,28 +164,6 @@ public partial class Response : IResponseBuilder
         return WithStatusCode((int)HttpStatusCode.NotFound);
     }
 
-    /// <inheritdoc cref="ITransformResponseBuilder.WithTransformer(bool)"/>
-    public IResponseBuilder WithTransformer(bool transformContentFromBodyAsFile)
-    {
-        return WithTransformer(TransformerType.Handlebars, transformContentFromBodyAsFile);
-    }
-
-    /// <inheritdoc cref="ITransformResponseBuilder.WithTransformer(ReplaceNodeOptions)"/>
-    public IResponseBuilder WithTransformer(ReplaceNodeOptions options)
-    {
-        return WithTransformer(TransformerType.Handlebars, false, options);
-    }
-
-    /// <inheritdoc />
-    public IResponseBuilder WithTransformer(TransformerType transformerType, bool transformContentFromBodyAsFile = false, ReplaceNodeOptions options = ReplaceNodeOptions.EvaluateAndTryToConvert)
-    {
-        UseTransformer = true;
-        TransformerType = transformerType;
-        UseTransformerForBodyAsFile = transformContentFromBodyAsFile;
-        TransformerReplaceNodeOptions = options;
-        return this;
-    }
-
     /// <inheritdoc />
     public IResponseBuilder WithDelay(TimeSpan delay)
     {
@@ -286,7 +264,7 @@ public partial class Response : IResponseBuilder
 
         if (UseTransformer)
         {
-            // Check if the body matcher is a RequestMessageProtoBufMatcher and try to to decode the byte-array to a BodyAsJson.
+            // Check if the body matcher is a RequestMessageProtoBufMatcher and try to decode the byte-array to a BodyAsJson.
             if (mapping.RequestMatcher is Request requestMatcher && requestMessage is RequestMessage request)
             {
                 var protoBufMatcher = requestMatcher.GetRequestMessageMatcher<RequestMessageProtoBufMatcher>()?.Matcher;

src/WireMock.Net/Transformers/Transformer.cs

@@ -198,7 +198,7 @@ internal class Transformer : ITransformer
 
     private JToken ReplaceSingleNode(ITransformerContext transformerContext, ReplaceNodeOptions options, string stringValue, object model)
     {
-        string transformedString = transformerContext.ParseAndRender(stringValue, model);
+        var transformedString = transformerContext.ParseAndRender(stringValue, model);
 
         if (!string.Equals(stringValue, transformedString))
         {
@@ -346,7 +346,7 @@ internal class Transformer : ITransformer
 
     private static IBodyData TransformBodyAsFile(ITransformerContext transformerContext, object model, IBodyData original, bool useTransformerForBodyAsFile)
     {
-        string transformedBodyAsFilename = transformerContext.ParseAndRender(original.BodyAsFile!, model);
+        var transformedBodyAsFilename = transformerContext.ParseAndRender(original.BodyAsFile!, model);
 
         if (!useTransformerForBodyAsFile)
         {
@@ -358,7 +358,7 @@ internal class Transformer : ITransformer
             };
         }
 
-        string text = transformerContext.FileSystemHandler.ReadResponseBodyAsString(transformedBodyAsFilename);
+        var text = transformerContext.FileSystemHandler.ReadResponseBodyAsString(transformedBodyAsFilename);
         return new BodyData
         {
             DetectedBodyType = BodyType.String,

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

@@ -602,22 +602,21 @@ public class ResponseWithTransformerTests
         Check.That(response.Message.BodyData!.BodyAsFile).Equals(@"c:\1\test.xml");
     }
 
-    [Theory]
-    [InlineData(TransformerType.Handlebars)]
-    //[InlineData(TransformerType.Scriban)] ["c:\\["1"]\\test.xml"]
-    //[InlineData(TransformerType.ScribanDotLiquid)]
-    public async Task Response_ProvideResponse_Transformer_WithBodyAsFile_And_TransformContentFromBodyAsFile(TransformerType transformerType)
+    [Fact]
+    public async Task Response_ProvideResponse_Transformer_WithBodyAsFile_And_TransformContentFromBodyAsFile()
     {
         // Assign
         var filesystemHandlerMock = new Mock<IFileSystemHandler>(MockBehavior.Strict);
-        filesystemHandlerMock.Setup(fs => fs.ReadResponseBodyAsString(It.IsAny<string>())).Returns("<xml MyUniqueNumber=\"{{request.query.MyUniqueNumber}}\"></xml>");
+        filesystemHandlerMock
+            .Setup(fs => fs.ReadResponseBodyAsString(It.IsAny<string>()))
+            .Returns("<xml MyUniqueNumber=\"{{request.query.MyUniqueNumber}}\"></xml>");
 
         _settings.FileSystemHandler = filesystemHandlerMock.Object;
 
         var request = new RequestMessage(new UrlDetails("http://localhost/foo?MyUniqueNumber=1"), "GET", ClientIp);
 
         var responseBuilder = Response.Create()
-            .WithTransformer(transformerType, true)
+            .WithTransformer(transformContentFromBodyAsFile: true)
             .WithBodyFromFile(@"c:\\{{request.query.MyUniqueNumber}}\\test.xml");
 
         // Act

test/WireMock.Net.Tests/WireMockServerTests.WithTransformer.cs

@@ -0,0 +1,98 @@
+// Copyright © WireMock.Net
+
+using System;
+using System.IO;
+using System.Net.Http;
+using System.Threading.Tasks;
+using FluentAssertions;
+using WireMock.RequestBuilders;
+using WireMock.ResponseBuilders;
+using WireMock.Server;
+using Xunit;
+
+namespace WireMock.Net.Tests;
+
+public partial class WireMockServerTests
+{
+    private const string RequestXml =
+        """
+        <xml>
+        	<Contact FirstName = "Stef" />
+        </xml>
+        """;
+
+    private readonly string _responseFilePath = Path.Combine(Environment.CurrentDirectory, "__admin", "mappings", "responseWithTransformer.xml");
+
+    [Fact]
+    public async Task WireMockServer_WithTransformer_WithBody_ShouldWork()
+    {
+        // Arrange
+        using var server = WireMockServer.Start();
+        server
+            .WhenRequest(req => req
+                .WithPath("/withbody")
+                .UsingPost())
+            .ThenRespondWith(rsp => rsp
+                .WithSuccess()
+                .WithBody(File.ReadAllText(_responseFilePath))
+                .WithTransformer());
+
+        // Act
+        var response = await GetResponseAsync(server, "/withbody");
+
+        // Assert
+        response.Should().Contain("Hello, Stef!");
+    }
+
+    [Fact]
+    public async Task WireMockServer_WithTransformerBefore_WithBodyFromFile_ShouldWork()
+    {
+        // Arrange
+        using var server = WireMockServer.Start();
+        server
+            .WhenRequest(req => req
+                .WithPath("/withbodyfromfile")
+                .UsingPost())
+            .ThenRespondWith(rsp => rsp
+                .WithSuccess()
+                .WithTransformer(transformContentFromBodyAsFile: true)
+                .WithBodyFromFile(_responseFilePath));
+
+        // Act
+        var response = await GetResponseAsync(server, "/withbodyfromfile");
+
+        // Assert
+        response.Should().Contain("Hello, Stef!");
+    }
+
+    [Fact]
+    public void WireMockServer_WithTransformerAfter_WithBodyFromFile_ShouldThrow()
+    {
+        // Act
+        var act = () =>
+        {
+            using var server = WireMockServer.Start();
+            server
+                .WhenRequest(req => req
+                    .WithPath("/")
+                    .UsingPost())
+                .ThenRespondWith(rsp => rsp
+                    .WithSuccess()
+                    .WithBodyFromFile(_responseFilePath)
+                    .WithTransformer(transformContentFromBodyAsFile: true));
+        };
+
+        // Assert
+        act.Should().Throw<InvalidOperationException>().WithMessage("WithTransformer should be used before WithBodyFromFile.");
+    }
+
+    private static async Task<string> GetResponseAsync(WireMockServer server, string relativePath)
+    {
+        using HttpClient httpClient = new HttpClient();
+        httpClient.BaseAddress = new Uri(server.Urls[0]);
+
+        using var requestContent = new StringContent(RequestXml);
+        using var responseMsg = await httpClient.PostAsync(relativePath, requestContent);
+        return await responseMsg.Content.ReadAsStringAsync();
+    }
+}

test/WireMock.Net.Tests/__admin/mappings/responseWithTransformer.xml

@@ -0,0 +1,3 @@
+<xml>
+    <hello>Hello, {{XPath.Evaluate request.body "//*[local-name()='Contact']/@FirstName"}}!</hello>
+</xml>