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

* Fix .WithBodyFromFile + .WithTransformer combination

* Ex

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>