Test coverage for configured derived type pairs in nested member mappings

Author: SteveWilkes

AgileMapper.UnitTests/WhenMappingDerivedTypes.cs

@@ -101,26 +101,20 @@ public void ShouldConditionallyMapDerivedTypesFromNestedMembers()
         {
             using (var mapper = Mapper.CreateNew())
             {
-                var sourceData = new { Discount = default(string), Report = default(string) };
-
                 mapper.WhenMapping
-                    .From(sourceData)
-                    .To<PersonViewModel>()
-                    .If((d, p) => d.Report != default(string))
-                    .MapTo<MysteryCustomerViewModel>()
-                    .And
-                    .If((d, p) => d.Discount != default(string))
-                    .MapTo<CustomerViewModel>();
-
-                var customerSource = new { Value = new { Discount = "0.2", Report = default(string) } };
-                var result = mapper.Map(customerSource).ToANew<PublicSetMethod<PersonViewModel>>();
+                    .From<PersonViewModel>()
+                    .To<Person>()
+                    .Map<CustomerViewModel>()
+                    .To<Customer>();
 
-                result.Value.ShouldBeOfType<CustomerViewModel>();
-
-                var mysteryCustomerSource = new { Value = new { Discount = default(string), Report = "Lovely!" } };
-                result = mapper.Map(mysteryCustomerSource).ToANew<PublicSetMethod<PersonViewModel>>();
+                var personSource = new PublicField<CustomerViewModel>
+                {
+                    Value = new MysteryCustomerViewModel { Discount = 0.2 }
+                };
+                var result = mapper.Map(personSource).ToANew<PublicSetMethod<Person>>();
 
-                result.Value.ShouldBeOfType<MysteryCustomerViewModel>();
+                result.Value.ShouldBeOfType<Customer>();
+                ((Customer)result.Value).Discount.ShouldBe(0.2);
             }
         }
     }

AgileMapper/ObjectPopulation/DerivedComplexTypeMappingsFactory.cs

@@ -37,10 +37,18 @@ public static Expression CreateFor(IObjectMappingData declaredTypeMappingData)
 
             var derivedTypeMappings = new List<Expression>();
 
+            bool declaredTypeHasUnconditionalTypePair;
+
             AddDeclaredSourceTypeMappings(
                 derivedTypePairs,
                 declaredTypeMappingData,
-                derivedTypeMappings);
+                derivedTypeMappings,
+                out declaredTypeHasUnconditionalTypePair);
+
+            if (declaredTypeHasUnconditionalTypePair)
+            {
+                return derivedTypeMappings.First();
+            }
 
             var typedObjectVariables = new List<ParameterExpression>();
 
@@ -56,7 +64,8 @@ public static Expression CreateFor(IObjectMappingData declaredTypeMappingData)
         private static void AddDeclaredSourceTypeMappings(
             IEnumerable<DerivedTypePair> derivedTypePairs,
             IObjectMappingData declaredTypeMappingData,
-            ICollection<Expression> derivedTypeMappings)
+            ICollection<Expression> derivedTypeMappings,
+            out bool declaredTypeHasUnconditionalTypePair)
         {
             var declaredTypeMapperData = declaredTypeMappingData.MapperData;
 
@@ -70,11 +79,20 @@ private static void AddDeclaredSourceTypeMappings(
                     derivedTypePair.DerivedTargetType);
 
                 var returnMappingResult = Expression.Return(declaredTypeMapperData.ReturnLabelTarget, derivedTypeMapping);
+                declaredTypeHasUnconditionalTypePair = (condition == null);
+
+                if (declaredTypeHasUnconditionalTypePair)
+                {
+                    derivedTypeMappings.Add(returnMappingResult);
+                    return;
+                }
 
                 var ifConditionThenMap = Expression.IfThen(condition, returnMappingResult);
 
                 derivedTypeMappings.Add(ifConditionThenMap);
             }
+
+            declaredTypeHasUnconditionalTypePair = false;
         }
 
         private static Expression GetTypePairCondition(DerivedTypePair derivedTypePair, IMemberMapperData mapperData)