Add answer to StackOverflow question: https://stackoverflow.com/quest…

…ions/66444118/how-to-use-bogus-faker-with-initialization-properties

Source/Bogus.Tests/StackOverflowQuestions/Question66444118.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Serialization;
+using FluentAssertions;
+using Xunit;
+
+namespace Bogus.Tests.StackOverflowQuestions
+{
+   //https://stackoverflow.com/questions/66444118/how-to-use-bogus-faker-with-initialization-properties
+   public class Question66444118 : SeededTest
+   {
+      [Fact]
+      public void can_reflect_private_backing_fields_in_fakerT()
+      {
+         var backingFieldBinder = new BackingFieldBinder();
+         var fooFaker = new Faker<Foo>(binder: backingFieldBinder)
+            .SkipConstructor()
+            .RuleFor(f => f.Name, f => f.Name.FullName());
+
+         var foo = fooFaker.Generate();
+         foo.Name.Should().NotBeNullOrWhiteSpace();
+      }
+
+      public class BackingFieldBinder : IBinder
+      {
+         public Dictionary<string, MemberInfo> GetMembers(Type t)
+         {
+            var availableFieldsForFakerT = new Dictionary<string, MemberInfo>();
+            var bindingFlags = BindingFlags.NonPublic | BindingFlags.Instance;
+            var allMembers = t.GetMembers(bindingFlags);
+            var allBackingFields = allMembers
+               .OfType<FieldInfo>()
+               .Where(fi => fi.IsPrivate && fi.IsInitOnly)
+               .Where(fi => fi.Name.EndsWith("__BackingField"))
+               .ToList();
+
+            foreach (var backingField in allBackingFields)
+            {
+               var fieldName = backingField.Name.Substring(1).Replace(">k__BackingField", "");
+               availableFieldsForFakerT.Add(fieldName, backingField);
+            }
+            return availableFieldsForFakerT;
+         }
+      }
+
+      public class Foo
+      {
+         public Foo(string name)
+         {
+            this.Name = name;
+         }
+         public string Name { get; }
+      }
+   }
+
+   public static class MyExtensionsForFakerT
+   {
+      public static Faker<T> SkipConstructor<T>(this Faker<T> fakerOfT) where T : class
+      {
+         return fakerOfT.CustomInstantiator(_ => FormatterServices.GetUninitializedObject(typeof(T)) as T);
+      }
+   }
+}