BuildByConstructor implementation

TestStack.Dossier.Tests/BuildTests.cs

@@ -80,5 +80,19 @@ public void GivenBuilder_WhenCallingSetImplicitly_ShouldOverrideValues()
             customer.LastName.ShouldBe("Lanningham");
             customer.YearJoined.ShouldBe(2014);
         }
+
+        [Fact]
+        public void GivenBuilderUsingConstructorReflection_WhenCallingBuildExplicitly_ShouldOverrideValues()
+        {
+            Customer customer = new AutoConstructorCustomerBuilder()
+                .WithFirstName("Bruce")
+                .WithLastName("Wayne")
+                .WhoJoinedIn(2012)
+                .Build();
+
+            customer.FirstName.ShouldBe("Bruce");
+            customer.LastName.ShouldBe("Wayne");
+            customer.YearJoined.ShouldBe(2012);
+        }
     }
 }

TestStack.Dossier.Tests/Builders/AutoConstructorCustomerBuilder.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TestStack.Dossier.Tests.Entities;
+
+namespace TestStack.Dossier.Tests.Builders
+{
+    class AutoConstructorCustomerBuilder : TestDataBuilder<Customer, AutoConstructorCustomerBuilder>
+    {
+        protected override Customer BuildObject()
+        {
+            return BuildByConstructor();
+        }
+
+        public AutoConstructorCustomerBuilder WithFirstName(string firstName)
+        {
+            return Set(x => x.FirstName, firstName);
+        }
+
+        public AutoConstructorCustomerBuilder WithLastName(string lastName)
+        {
+            return Set(x => x.LastName, lastName);
+        }
+
+        public AutoConstructorCustomerBuilder WhoJoinedIn(int year)
+        {
+            return Set(x => x.YearJoined, year);
+        }
+    }
+}

TestStack.Dossier.Tests/TestStack.Dossier.Tests.csproj

@@ -13,7 +13,7 @@
     <FileAlignment>512</FileAlignment>
     <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\</SolutionDir>
     <TargetFrameworkProfile />
-    <NuGetPackageImportStamp>d4853673</NuGetPackageImportStamp>
+    <NuGetPackageImportStamp>660882d1</NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -54,6 +54,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Builders\AutoConstructorCustomerBuilder.cs" />
     <Compile Include="ChildBuilderTests.cs" />
     <Compile Include="Entities\CustomerClass.cs" />
     <Compile Include="DataSources\DataSourceTests.cs" />
@@ -100,6 +101,9 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

TestStack.Dossier/TestDataBuilder.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
+using Ploeh.AutoFixture;
 using TestStack.Dossier.Lists;
 
 namespace TestStack.Dossier
@@ -15,7 +16,7 @@ public abstract class TestDataBuilder<TObject, TBuilder>
         where TObject : class
         where TBuilder : TestDataBuilder<TObject, TBuilder>, new()
     {
-        private readonly Dictionary<string, object> _properties = new Dictionary<string, object>();
+        private readonly Dictionary<string, object> _properties = new Dictionary<string, object>(StringComparer.InvariantCultureIgnoreCase);
         private ProxyBuilder<TObject> _proxyBuilder;
 
         /// <summary>
@@ -117,7 +118,7 @@ public TValue Get<TValue>(Expression<Func<TObject, TValue>> property)
             if (!Has(property))
                 return Any.Get(property);
 
-            return (TValue)_properties[PropertyNameGetter.Get(property)];
+            return (TValue) _properties[PropertyNameGetter.Get(property)];
         }
 
         /// <summary>
@@ -182,5 +183,47 @@ protected virtual TChildBuilder GetChildBuilder<TChildObject, TChildBuilder>(Fun
                 modifier(childBuilder);
             return childBuilder;
         }
+
+        /// <summary>
+        /// Builds the object using the constructor with the most arguments.
+        /// </summary>
+        /// <returns></returns>
+        protected TObject BuildByConstructor()
+        {
+            var longestConstructor = typeof (TObject)
+                .GetConstructors()
+                .OrderByDescending(x => x.GetParameters().Length)
+                .FirstOrDefault();
+
+            if (longestConstructor == null) throw new ObjectCreationException();
+
+            var parameterValues = longestConstructor
+                .GetParameters()
+                .Select(x => CallGetWithType(x.Name, x.ParameterType));
+
+            return (TObject) longestConstructor.Invoke(parameterValues.ToArray());
+        }
+
+        private object CallGetWithType(string propertyName, Type propertyType)
+        {
+            // Make a Func<TObj, TPropertyType>
+            var expressionDelegateType = typeof(Func<,>).MakeGenericType(typeof(TObject), propertyType);
+
+            // Make an expression parameter of type TObj
+            var tObjParameterType = Expression.Parameter(typeof(TObject));
+
+            var valueStoredInBuilder = typeof(TBuilder)
+                .GetMethod("Get")
+                .MakeGenericMethod(propertyType)
+                .Invoke(this, new object[]
+            {
+                Expression.Lambda(
+                    expressionDelegateType,
+                    Expression.Property(tObjParameterType, propertyName),
+                    tObjParameterType)
+            });
+
+            return valueStoredInBuilder;
+        }
     }
 }