Add Random Regex (using Fare) (#236)

* Xeger

* update example

* 1.0.7

* Fix tests for Handlebars_Xeger

* ReplaceNodeValue

* 1.0.5

* readme

src/WireMock.Net/Transformers/HandleBarsXeger.cs

@@ -0,0 +1,39 @@
+using System;
+using Fare;
+using HandlebarsDotNet;
+using WireMock.Validation;
+
+namespace WireMock.Transformers
+{
+    internal static class HandleBarsXeger
+    {
+        public static void Register(IHandlebars handlebarsContext)
+        {
+            handlebarsContext.RegisterHelper("Xeger", (writer, context, arguments) =>
+            {
+                string value = ParseArgumentAndGenerate(arguments);
+                writer.Write(value);
+            });
+
+            handlebarsContext.RegisterHelper("Xeger", (writer, options, context, arguments) =>
+            {
+                string value = ParseArgumentAndGenerate(arguments);
+                options.Template(writer, value);
+            });
+        }
+
+        private static string ParseArgumentAndGenerate(object[] arguments)
+        {
+            Check.Condition(arguments, args => args.Length == 1, nameof(arguments));
+            Check.NotNull(arguments[0], "arguments[0]");
+
+            switch (arguments[0])
+            {
+                case string pattern:
+                    return new Xeger(pattern).Generate();
+            }
+
+            throw new NotSupportedException($"The value '{arguments[0]}' with type '{arguments[0]?.GetType()}' cannot be used in Handlebars Xeger.");
+        }
+    }
+}