ProxyUrlTransformer (#1361)

* ProxyUrlTransformer

* tests

* Update src/WireMock.Net.Shared/Settings/ProxyUrlReplaceSettings.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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

@@ -0,0 +1,98 @@
+using System.Globalization;
+using Moq;
+using WireMock.Handlers;
+using WireMock.Proxy;
+using WireMock.Settings;
+using WireMock.Types;
+using Xunit;
+
+namespace WireMock.Net.Tests.Proxy;
+
+public class ProxyUrlTransformerTests
+{
+    private readonly Mock<IFileSystemHandler> _fileSystemHandlerMock = new();
+
+    [Fact]
+    public void Transform_WithUseTransformerFalse_PerformsSimpleReplace_CaseSensitive()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = null,
+            OldValue = "/old",
+            NewValue = "/new",
+            IgnoreCase = false
+        };
+
+        var url = "http://example.com/old/path";
+        var expected = "http://example.com/new/path";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void Transform_WithUseTransformerFalse_PerformsSimpleReplace_IgnoreCase()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = null, // UseTransformer == false
+            OldValue = "/OLD",
+            NewValue = "/new",
+            IgnoreCase = true
+        };
+
+        var url = "http://example.com/old/path"; // lowercase 'old' but OldValue is uppercase
+        var expected = "http://example.com/new/path";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void Transform_WithUseTransformerTrue_UsesTransformer_ToTransformUrl()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        // Handlebars is the default TransformerType; the TransformTemplate uses the model directly.
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = "{{this}}-transformed",
+            // TransformerType defaults to Handlebars but set explicitly for clarity.
+            TransformerType = TransformerType.Handlebars
+        };
+
+        var url = "http://example.com/path";
+        var expected = "http://example.com/path-transformed";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+}