add fill the Nullable<enum> properties

src/GenFu/FillerManager.cs

@@ -202,6 +202,10 @@ public IPropertyFiller GetFiller(PropertyInfo propertyInfo)
                 {
                     result = new EnumFiller(propertyInfo.PropertyType);
                 }
+                else if (propertyInfo.PropertyType.GetNullableUnderlyingType().IsEnum)
+                {
+                    result = new NullableEnumFiller(propertyInfo.PropertyType.GetNullableUnderlyingType());
+                }
                 else
                 {
                     //TODO: Can we build a custom filler here for other value types that we have not explicitly implemented (eg. long, decimal, etc.)

src/GenFu/Fillers/EnumFiller.cs

@@ -17,3 +17,19 @@ public override object GetValue(object instance)
         return values.GetValue(new Random().Next(values.Length));
     }
 }
+
+public class NullableEnumFiller : PropertyFiller<Enum?>
+{
+    readonly Type _type;
+    public NullableEnumFiller(Type type)
+        : base(typeof(object), "*", true)
+    {
+        this._type = type;
+    }
+
+    public override object GetValue(object instance)
+    {
+        var values = Enum.GetValues(_type);
+        return values.GetValue(new Random().Next(values.Length));
+    }
+}

src/GenFu/ReflectionHelpers.cs

@@ -1,6 +1,11 @@
-namespace GenFu;
+using System;
+
+namespace GenFu;
 
 internal static class ReflectionHelpers
 {
-
+    public static Type GetNullableUnderlyingType(this Type type)
+    {
+        return Nullable.GetUnderlyingType(type);
+    }
 }

tests/GenFu.Tests/TestEntities/Nullables.cs

@@ -14,4 +14,5 @@ public class Nullables
     public short? NullableShort { get; set; }
     public bool? NullableBoolean { get; set; }
     public char? NullableChar { get; set; }
+    public PropertyType? NullableEnum { get; set; }
 }

tests/GenFu.Tests/When_filling_nullables.cs

@@ -59,4 +59,10 @@ void A_nullable_char_should_be_filled()
     {
         Assert.True(A.New<Nullables>().NullableChar.HasValue);
     }
+
+    [Fact]
+    void A_nullable_enum_should_be_filled()
+    {
+        Assert.True(A.New<Nullables>().NullableEnum.HasValue);
+    }
 }