From 1f1524cf60006c3e8f4053c0f756560eef3b2174 Mon Sep 17 00:00:00 2001
From: Leandro Fernandes Vieira <leandro.vieira@stone.com.br>
Date: Wed, 13 May 2020 23:46:51 -0300
Subject: [PATCH] adds logic to build new expression of types without parameter
 less constructor and tests

---
 .../ComplexTypeTests.cs                       | 35 +++++++++++++++++++
 .../ComplexTypeExpressionFactory.cs           | 28 ++++++++++++---
 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/src/CloneExtensions.UnitTests/ComplexTypeTests.cs b/src/CloneExtensions.UnitTests/ComplexTypeTests.cs
index c1e5061..dd34b9f 100644
--- a/src/CloneExtensions.UnitTests/ComplexTypeTests.cs
+++ b/src/CloneExtensions.UnitTests/ComplexTypeTests.cs
@@ -88,6 +88,23 @@ public void GetClone_CircularDependency_ItemsClonedCorrectly()
             Assert.AreSame(target.First, target.Second, "Are the same");
         }
 
+        [TestMethod]
+        public void GetClone_ConstructorClass_ClonnedProperly()
+        {
+            var source = new ConstructorClass(null, 3, DateTime.Now, new List<string>(), null, default)
+            {
+                PropertyA = 3,
+                PropertyB = Guid.NewGuid().ToString(),
+                PropertyC = DateTime.Now
+            };
+
+            var target = CloneFactory.GetClone(source);
+
+            Assert.AreEqual(source.PropertyA, target.PropertyA);
+            Assert.AreEqual(source.PropertyB, target.PropertyB);
+            Assert.AreEqual(source.PropertyC, target.PropertyC);
+        }
+
         [TestMethod]
         public void GetClone_DerivedTypeWithShadowedProperty_ClonnedProperly()
         {
@@ -226,5 +243,23 @@ class DerivedClassOne : BaseClassOne
             // use the default implementation for VirtualProperty2
             public override string VirtualProperty3 { get; set; }
         }
+
+        class ConstructorClass
+        {
+            public ConstructorClass(
+                BaseClassOne a, 
+                int? b, 
+                DateTime c,
+                List<string> d, 
+                IInterface e,
+                SimpleStruct f)
+            {
+
+            }
+
+            public int PropertyA { get; set; }
+            public string PropertyB { get; set; }
+            public DateTime PropertyC { get; set; }
+        }
     }
 }
diff --git a/src/CloneExtensions/ExpressionFactories/ComplexTypeExpressionFactory.cs b/src/CloneExtensions/ExpressionFactories/ComplexTypeExpressionFactory.cs
index e226c86..c6a4f89 100644
--- a/src/CloneExtensions/ExpressionFactories/ComplexTypeExpressionFactory.cs
+++ b/src/CloneExtensions/ExpressionFactories/ComplexTypeExpressionFactory.cs
@@ -66,21 +66,39 @@ private Expression GetInitializationExpression()
             var funcInvokeCall = Expression.Call(dictIndex, "Invoke", null, Expression.Convert(Source, typeof(object)));
             var initializerCall = Expression.Convert(funcInvokeCall, _type);
 
-            // parameterless constructor
-            var constructor = _type.GetConstructor(new Type[0]);
-
             return Expression.IfThenElse(
                 containsKeyCall,
                 Expression.Assign(Target, initializerCall),
-                (_type.IsAbstract() || _type.IsInterface() || (!_type.IsValueType() && constructor == null)) ?
+                (_type.IsAbstract() || _type.IsInterface()) ?
                     Helpers.GetThrowInvalidOperationExceptionExpression(_type) :
                     Expression.Assign(
                         Target,
-                        _type.IsValueType() ? (Expression)Source : Expression.New(_type)
+                        _type.IsValueType() ? (Expression)Source : GetNewExpressionFor(_type)
                     )
             );
         }
 
+        private static NewExpression GetNewExpressionFor(Type objType)
+        {
+            ConstructorInfo ctor = objType
+                .GetConstructors()
+                .OrderBy(x => x.GetParameters().Length)
+                .First();
+
+            return
+                Expression.New
+                (
+                    ctor,
+                    ctor.GetParameters().Select(p =>
+                        p.IsOptional
+                            ? Expression.Convert(Expression.Constant(p.DefaultValue), p.ParameterType)
+                            : p.ParameterType.IsAbstract() || p.ParameterType.IsInterface() || 
+                             (p.ParameterType.IsValueType() && Nullable.GetUnderlyingType(p.ParameterType) == null)
+                                ? Expression.Default(p.ParameterType)
+                                : (Expression)GetNewExpressionFor(p.ParameterType))
+                );
+        }
+
         private Expression GetFieldsCloneExpression(Func<Type, Expression, Expression> getItemCloneExpression)
         {
             var fields = from f in _type.GetTypeInfo().GetFields(BindingFlags.Public | BindingFlags.Instance)