enable opt-in to case-insensitive mapping of enum values (#9)

* enable opt-in to case-insensitive mapping of enum values
#7

* adopt changes after review by @HenkKin ([email protected])

Author: earloc

src/AutoMapper.Extensions.EnumMapping.Tests/EnumValueMappingByName.cs

@@ -33,6 +33,33 @@ public void Should_map_enum_by_name()
             }
         }
 
+        public class ValidIgnoreCase : AutoMapperSpecBase
+        {
+            Destination _result;
+            public enum Source { Default, FOO, Bar, FooBar }
+            public enum Destination { fOObAR, DefaulT, Bar, Foo }
+
+            protected override MapperConfiguration Configuration { get; } = new MapperConfiguration(cfg =>
+            {
+                cfg.EnableEnumMappingValidation();
+                cfg.CreateMap<Source, Destination>()
+                    .ConvertUsingEnumMapping(opt => opt.MapByName(true));
+            });
+
+            protected override void Because_of()
+            {
+                _result = Mapper.Map<Source, Destination>(Source.FooBar);
+            }
+
+            [Fact]
+            public void Should_map_enum_by_name()
+            {
+                _result.ShouldBe(Destination.fOObAR);
+                ((int)_result).ShouldNotBe((int)Source.FooBar);
+            }
+
+        }
+
         public class ValidCustomMapping : AutoMapperSpecBase
         {
             Destination _result;

src/AutoMapper.Extensions.EnumMapping/IEnumConfigurationExpression.cs

@@ -14,8 +14,9 @@ public interface IEnumConfigurationExpression<in TSource, in TDestination>
         /// <summary>
         /// Map enum values by name
         /// </summary>
+        /// <param name="ignoreCase">Optional, ignore casing for enum value names</param>
         /// <returns>Enum configuration options</returns>
-        IEnumConfigurationExpression<TSource, TDestination> MapByName();
+        IEnumConfigurationExpression<TSource, TDestination> MapByName(bool ignoreCase = false);
 
         /// <summary>
         /// (default) Map enum values by value (underlying value type)

src/AutoMapper.Extensions.EnumMapping/Internal/EnumMappingFeature.cs

@@ -10,6 +10,8 @@ internal class EnumMappingFeature<TSource, TDestination> : IMappingFeature, IEnu
         where TDestination : struct, Enum
     {
         protected EnumMappingType EnumMappingType = EnumMappingType.Value;
+        protected bool IgnoreCase;
+
         protected readonly Dictionary<TSource, TDestination> EnumValueMappingsOverride = new Dictionary<TSource, TDestination>();
 
         public void Configure(TypeMap typeMap)
@@ -50,15 +52,13 @@ private Dictionary<TSource, TDestination> CreateDefaultEnumValueMappings(Type so
 
             if (EnumMappingType == EnumMappingType.Name)
             {
-                const bool ignoreCase = false;
-
                 foreach (TDestination destinationEnumValue in destinationEnumValues)
                 {
                     var destinationEnumName = Enum.GetName(destinationType, destinationEnumValue);
 
                     if (!string.IsNullOrWhiteSpace(destinationEnumName))
                     {
-                        if (Enum.TryParse(destinationEnumName, ignoreCase, out TSource sourceEnumValue))
+                        if (Enum.TryParse(destinationEnumName, IgnoreCase, out TSource sourceEnumValue))
                         {
                             enumValueMappings.Add(sourceEnumValue, destinationEnumValue);
                         }
@@ -89,9 +89,10 @@ private Dictionary<TSource, TDestination> CreateDefaultEnumValueMappings(Type so
             return enumValueMappings;
         }
 
-        public IEnumConfigurationExpression<TSource, TDestination> MapByName()
+        public IEnumConfigurationExpression<TSource, TDestination> MapByName(bool ignoreCase = false)
         {
             EnumMappingType = EnumMappingType.Name;
+            IgnoreCase = ignoreCase;
             return this;
         }
 
@@ -113,7 +114,7 @@ public IMappingFeature Reverse()
 
             if (EnumMappingType == EnumMappingType.Name)
             {
-                reverseEnumConfigurationExpression.MapByName();
+                reverseEnumConfigurationExpression.MapByName(IgnoreCase);
             }
             else
             {