Settled on object builder design

Author: mwhelan

TestStack.Dossier.Tests/Builders/AutoConstructorCustomerBuilder.cs

@@ -1,14 +1,12 @@
-using TestStack.Dossier.BuildStrategies;
+using TestStack.Dossier.Factories;
 using TestStack.Dossier.Tests.Stubs.Entities;
 
 namespace TestStack.Dossier.Tests.Builders
 {
     class AutoConstructorCustomerBuilder : TestDataBuilder<Customer, AutoConstructorCustomerBuilder>
     {
-        protected override Customer BuildObject()
-        {
-            return BuilderStrategy.Apply<UseConstructor>().BuildObject(this);
-        }
+        public AutoConstructorCustomerBuilder() 
+            : base(new ConstructorFactory()) { }
 
         public AutoConstructorCustomerBuilder WithFirstName(string firstName)
         {

TestStack.Dossier/BuildStrategies/BuilderStrategy.cs

@@ -1,10 +1,16 @@
-using System;
-
-namespace TestStack.Dossier
+namespace TestStack.Dossier
 {
+    /// <summary>
+    /// A stand-alone class for building objects on the fly.
+    /// </summary>
+    /// <typeparam name="T">The type of object this class generates.</typeparam>
     public class Builder<T> : TestDataBuilder<T, Builder<T>>
         where T : class
     {
+        /// <summary>
+        /// Initialises a new Builder.
+        /// </summary>
+        /// <returns>Returns a new instance of a Builder for the type of T</returns>
         public static Builder<T> CreateNew()
         {
             return new Builder<T>();

TestStack.Dossier/Builder.cs

@@ -1,11 +1,11 @@
 using Ploeh.AutoFixture;
 
-namespace TestStack.Dossier.BuildStrategies
+namespace TestStack.Dossier.Factories
 {
     /// <summary>
     /// Creates an instance of an object by setting all public and private properties.
     /// </summary>
-    public class AllProperties : IBuildStrategy
+    public class AllPropertiesFactory : IFactory
     {
         /// <inheritdoc />
         public TObject BuildObject<TObject, TBuilder>(TestDataBuilder<TObject, TBuilder> builder)

…Dossier/BuildStrategies/AllProperties.cs …ossier/Factories/AllPropertiesFactory.csTestStack.Dossier/BuildStrategies/AllProperties.cs renamed to TestStack.Dossier/Factories/AllPropertiesFactory.cs TestStack.Dossier/BuildStrategies/AllProperties.cs renamed to TestStack.Dossier/Factories/AllPropertiesFactory.cs

@@ -1,11 +1,11 @@
 using Ploeh.AutoFixture;
 
-namespace TestStack.Dossier.BuildStrategies
+namespace TestStack.Dossier.Factories
 {
     /// <summary>
     /// Creates an instance of an object with AutoFixture.
     /// </summary>
-    public class AutoFixture : IBuildStrategy
+    public class AutoFixtureFactory : IFactory
     {
         /// <inheritdoc />
         public TObject BuildObject<TObject, TBuilder>(TestDataBuilder<TObject, TBuilder> builder) 

…k.Dossier/BuildStrategies/AutoFixture.cs ….Dossier/Factories/AutoFixtureFactory.csTestStack.Dossier/BuildStrategies/AutoFixture.cs renamed to TestStack.Dossier/Factories/AutoFixtureFactory.cs TestStack.Dossier/BuildStrategies/AutoFixture.cs renamed to TestStack.Dossier/Factories/AutoFixtureFactory.cs

@@ -1,14 +1,15 @@
 using System;
 using System.Linq;
 using System.Linq.Expressions;
+using System.Reflection;
 using Ploeh.AutoFixture;
 
-namespace TestStack.Dossier.BuildStrategies
+namespace TestStack.Dossier.Factories
 {
     /// <summary>
     /// Builds the object using the constructor with the most arguments.
     /// </summary>
-    public class UseConstructor : IBuildStrategy
+    public class ConstructorFactory : IFactory
     {
         /// <inheritdoc />
         public TObject BuildObject<TObject, TBuilder>(TestDataBuilder<TObject, TBuilder> builder)
@@ -24,24 +25,22 @@ public TObject BuildObject<TObject, TBuilder>(TestDataBuilder<TObject, TBuilder>
 
             var parameterValues = longestConstructor
                 .GetParameters()
-                .Select(x => CallGetWithType(x.Name, x.ParameterType, typeof(TObject), typeof(TBuilder)));
+                .Select(x => CallGetWithType(x.Name, x.ParameterType, typeof(TObject), typeof(TBuilder), builder));
 
             return (TObject)longestConstructor.Invoke(parameterValues.ToArray());
         }
 
-        private object CallGetWithType(string propertyName, Type propertyType, Type objectType, Type builderType)
+        private static object CallGetWithType(string propertyName, Type propertyType, Type objectType, Type builderType, object builder)
         {
             // Make a Func<TObj, TPropertyType>
             var expressionDelegateType = typeof(Func<,>).MakeGenericType(objectType, propertyType);
-
-            // Make an expression parameter of type TObj
             var tObjParameterType = Expression.Parameter(objectType);
 
-            var valueStoredInBuilder = builderType
+            var closedGenericGetMethod = builderType
                 .GetMethods()
-                .First(method => method.Name == "Get" && method.ContainsGenericParameters && method.GetGenericArguments().Length == 1)
-                .MakeGenericMethod(propertyType)
-                .Invoke(this, new object[]
+                .First(IsGenericGetMethod()) 
+                .MakeGenericMethod(propertyType);
+            var valueStoredInBuilder = closedGenericGetMethod.Invoke(builder, new object[]
                 {
                     Expression.Lambda(
                         expressionDelegateType,
@@ -52,5 +51,9 @@ private object CallGetWithType(string propertyName, Type propertyType, Type obje
             return valueStoredInBuilder;
         }
 
+        private static Func<MethodInfo, bool> IsGenericGetMethod()
+        {
+            return method => method.Name == "Get" && method.ContainsGenericParameters && method.GetGenericArguments().Length == 1;
+        }
     }
 }

…ossier/BuildStrategies/UseConstructor.cs ….Dossier/Factories/ConstructorFactory.csTestStack.Dossier/BuildStrategies/UseConstructor.cs renamed to TestStack.Dossier/Factories/ConstructorFactory.cs TestStack.Dossier/BuildStrategies/UseConstructor.cs renamed to TestStack.Dossier/Factories/ConstructorFactory.cs

@@ -1,9 +1,9 @@
-namespace TestStack.Dossier.BuildStrategies
+namespace TestStack.Dossier.Factories
 {
     /// <summary>
     /// Interface for object building strategies
     /// </summary>
-    public interface IBuildStrategy
+    public interface IFactory
     {
         /// <summary>
         /// Takes a builder and generates an object of the specified type.

…ossier/BuildStrategies/IBuildStrategy.cs TestStack.Dossier/Factories/IFactory.csTestStack.Dossier/BuildStrategies/IBuildStrategy.cs renamed to TestStack.Dossier/Factories/IFactory.cs TestStack.Dossier/BuildStrategies/IBuildStrategy.cs renamed to TestStack.Dossier/Factories/IFactory.cs

@@ -1,11 +1,11 @@
 using Ploeh.AutoFixture;
 
-namespace TestStack.Dossier.BuildStrategies
+namespace TestStack.Dossier.Factories
 {
     /// <summary>
     /// Creates an instance of an object by setting all public properties but not private properties.
     /// </summary>
-    public class PublicProperties : IBuildStrategy
+    public class PublicPropertiesFactory : IFactory
     {
         /// <inheritdoc />
         public TObject BuildObject<TObject, TBuilder>(TestDataBuilder<TObject, TBuilder> builder)

…sier/BuildStrategies/PublicProperties.cs …ier/Factories/PublicPropertiesFactory.csTestStack.Dossier/BuildStrategies/PublicProperties.cs renamed to TestStack.Dossier/Factories/PublicPropertiesFactory.cs TestStack.Dossier/BuildStrategies/PublicProperties.cs renamed to TestStack.Dossier/Factories/PublicPropertiesFactory.cs

@@ -28,8 +28,7 @@ public interface IAnonymousValueSupplier
         /// <summary>
         /// Return an anonymous value for the given property and fixture.
         /// </summary>
-        /// <typeparam name="TObject">The type that the property is enclosed in</typeparam>
-        /// <typeparam name="TValue">The type of the target property - the required anonymous value is of this type</typeparam>
+        /// <param name="type">The type that the property is enclosed in</param>
         /// <param name="any">Anonymous value fixture</param>
         /// <param name="propertyName">The name of the property to return an anonymous value for</param>
         /// <returns>The anonymous value</returns>

TestStack.Dossier/IAnonymousValueSupplier.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
-using TestStack.Dossier.BuildStrategies;
+using TestStack.Dossier.Factories;
 using TestStack.Dossier.Lists;
 
 namespace TestStack.Dossier
@@ -15,6 +15,7 @@ public abstract class TestDataBuilder<TObject, TBuilder>
         where TObject : class
         where TBuilder : TestDataBuilder<TObject, TBuilder>, new()
     {
+        private readonly IFactory _factory;
         private readonly Dictionary<string, object> _properties = new Dictionary<string, object>(StringComparer.InvariantCultureIgnoreCase);
         private ProxyBuilder<TObject> _proxyBuilder;
 
@@ -27,7 +28,16 @@ public abstract class TestDataBuilder<TObject, TBuilder>
         /// Default Constructor.
         /// </summary>
         protected TestDataBuilder()
+            : this(new AllPropertiesFactory())
         {
+        }
+
+        /// <summary>
+        /// Allow object builder factory to be passed in
+        /// </summary>
+        protected TestDataBuilder(IFactory factory)
+        {
+            _factory = factory;
             Any = new AnonymousValueFixture();
         }
 
@@ -76,9 +86,7 @@ public static implicit operator List<TObject>(TestDataBuilder<TObject, TBuilder>
         /// <returns>The built object</returns>
         protected virtual TObject BuildObject()
         {
-            var model = BuilderStrategy
-                .Apply<AllProperties>()
-                .BuildObject(this);
+            var model = _factory.BuildObject(this);
 
             return model;
         }