diff --git a/src/Orchard.Tests/ContentManagement/DefaultContentManagerTests.cs b/src/Orchard.Tests/ContentManagement/DefaultContentManagerTests.cs
index d9613db7f..2f6f706fc 100644
--- a/src/Orchard.Tests/ContentManagement/DefaultContentManagerTests.cs
+++ b/src/Orchard.Tests/ContentManagement/DefaultContentManagerTests.cs
@@ -532,13 +532,13 @@ namespace Orchard.Tests.ContentManagement {
         }
 
 
-        [Test, Ignore("Fix pending")]
+        [Test]
         public void ExistingTypeAndPartDefinitionShouldBeUsed() {
             var alphaType = new ContentTypeDefinitionBuilder()
                 .Named(DefaultAlphaName)
                 .WithSetting("x", "1")
                 .WithPart("foo")
-                .WithPart("Flavored", part => part.WithSetting("spin", "clockwise"))
+                .WithPart("FlavoredPart", part => part.WithSetting("spin", "clockwise"))
                 .Build();
 
             _contentDefinitionManager
diff --git a/src/Orchard.Tests/DisplayManagement/DefaultDisplayManagerTests.cs b/src/Orchard.Tests/DisplayManagement/DefaultDisplayManagerTests.cs
index bb5b9bef6..e05bec7c3 100644
--- a/src/Orchard.Tests/DisplayManagement/DefaultDisplayManagerTests.cs
+++ b/src/Orchard.Tests/DisplayManagement/DefaultDisplayManagerTests.cs
@@ -25,7 +25,6 @@ namespace Orchard.Tests.DisplayManagement {
                 CurrentTheme = new ExtensionDescriptor { Id = "Hello" }
             };
 
-
             builder.RegisterType<DefaultDisplayManager>().As<IDisplayManager>();
             builder.RegisterType<TestShapeTableManager>().As<IShapeTableManager>();
             builder.RegisterType<TestWorkContextAccessor>().As<IWorkContextAccessor>();
diff --git a/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs b/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
index b2e7dd2c7..70ea3f52f 100644
--- a/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
+++ b/src/Orchard.Tests/Environment/Extensions/ExtensionManagerTests.cs
@@ -309,10 +309,12 @@ Features:
             }
         }
 
-        [Test, Ignore("This assertion appears to be inconsistent with the comment in extension manager - an empty feature is returned")]
-        public void ExtensionManagerShouldThrowIfFeatureDoesNotExist() {
-            var featureDescriptor = new FeatureDescriptor { Id = "NoSuchFeature", Extension = new ExtensionDescriptor { Name = "NoSuchFeature" } };
-            Assert.Throws<ArgumentException>(() => _manager.LoadFeatures(new[] { featureDescriptor }));
+        [Test]
+        public void ExtensionManagerShouldReturnEmptyFeatureIfFeatureDoesNotExist() {
+            var featureDescriptor = new FeatureDescriptor { Id = "NoSuchFeature", Extension = new ExtensionDescriptor { Id = "NoSuchFeature" } };
+            Feature feature = _manager.LoadFeatures(new[] { featureDescriptor }).First();
+            Assert.AreEqual(featureDescriptor, feature.Descriptor);
+            Assert.AreEqual(0, feature.ExportedTypes.Count());
         }
 
         [Test]
diff --git a/src/Orchard.Tests/Mvc/OrchardControllerFactoryTests.cs b/src/Orchard.Tests/Mvc/OrchardControllerFactoryTests.cs
index 6b6ee4950..38ec3b36c 100644
--- a/src/Orchard.Tests/Mvc/OrchardControllerFactoryTests.cs
+++ b/src/Orchard.Tests/Mvc/OrchardControllerFactoryTests.cs
@@ -25,6 +25,7 @@ namespace Orchard.Tests.Mvc {
                 .Keyed<IController>(typeof(FooController))
                 .WithMetadata("ControllerType", typeof(FooController))
                 .InstancePerDependency();
+
             builder.RegisterType<BarController>()
                 .Keyed<IController>("/bar")
                 .Keyed<IController>(typeof(BarController))
@@ -59,8 +60,7 @@ namespace Orchard.Tests.Mvc {
             Assert.That(controller, Is.TypeOf<ReplacementFooController>());
         }
 
-        [Test]
-        [Ignore("OrchardControllerFactory depends on metadata, calling base when no context is causing errors.")]
+        [Test, Ignore("OrchardControllerFactory depends on metadata, calling base when no context is causing errors.")]
         public void WhenNullOrMissingContainerNormalControllerFactoryRulesShouldBeUsedAsFallback() {
             var requestContext = GetRequestContext(null);
             var controller = _controllerFactory.CreateController(requestContext, "foo");
diff --git a/src/Orchard.Tests/Stubs/StubCacheManager.cs b/src/Orchard.Tests/Stubs/StubCacheManager.cs
index 36d215d1b..0537ef6e0 100644
--- a/src/Orchard.Tests/Stubs/StubCacheManager.cs
+++ b/src/Orchard.Tests/Stubs/StubCacheManager.cs
@@ -16,4 +16,4 @@ namespace Orchard.Tests.Stubs {
             return _defaultCacheManager.GetCache<TKey, TResult>();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Orchard/Caching/DefaultCacheHolder.cs b/src/Orchard/Caching/DefaultCacheHolder.cs
index 972882b1a..d30d886e9 100644
--- a/src/Orchard/Caching/DefaultCacheHolder.cs
+++ b/src/Orchard/Caching/DefaultCacheHolder.cs
@@ -2,6 +2,10 @@ using System;
 using System.Collections.Concurrent;
 
 namespace Orchard.Caching {
+    /// <summary>
+    /// Provides the default implementation for a cache holder.
+    /// The cache holder is responsible for actually storing the references to cached entities.
+    /// </summary>
     public class DefaultCacheHolder : ICacheHolder {
         private readonly ConcurrentDictionary<CacheKey, object> _caches = new ConcurrentDictionary<CacheKey, object>();
 
@@ -11,10 +15,17 @@ namespace Orchard.Caching {
             }
         }
 
+        /// <summary>
+        /// Gets a Cache entry from the cache. If none is found, an empty one is created and returned.
+        /// </summary>
+        /// <typeparam name="TKey">The type of the key within the component.</typeparam>
+        /// <typeparam name="TResult">The type of the result.</typeparam>
+        /// <param name="component">The component context.</param>
+        /// <returns>An entry from the cache, or a new, empty one, if none is found.</returns>
         public ICache<TKey, TResult> GetCache<TKey, TResult>(Type component) {
             var cacheKey = new CacheKey(component, typeof(TKey), typeof(TResult));
             var result = _caches.GetOrAdd(cacheKey, k => new Cache<TKey, TResult>());
             return (Cache<TKey, TResult>)result;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Orchard/Caching/DefaultCacheManager.cs b/src/Orchard/Caching/DefaultCacheManager.cs
index 8fdb2eebc..a77303028 100644
--- a/src/Orchard/Caching/DefaultCacheManager.cs
+++ b/src/Orchard/Caching/DefaultCacheManager.cs
@@ -1,15 +1,30 @@
 using System;
 
 namespace Orchard.Caching {
+    /// <summary>
+    /// Provides the default implementation for a cache manager. 
+    /// The cache manager provides an abstraction over the cache holder allowing it to be easily swaped and isolating it within a component context.
+    /// </summary>
     public class DefaultCacheManager : ICacheManager {
         private readonly Type _component;
         private readonly ICacheHolder _cacheHolder;
 
+        /// <summary>
+        /// Constructs a new cache manager for a given component type and with a specific cache holder implementation.
+        /// </summary>
+        /// <param name="component">The component to which the cache applies (context).</param>
+        /// <param name="cacheHolder">The cache holder that contains the entities cached.</param>
         public DefaultCacheManager(Type component, ICacheHolder cacheHolder) {
             _component = component;
             _cacheHolder = cacheHolder;
         }
 
+        /// <summary>
+        /// Gets a cache entry from the cache holder.
+        /// </summary>
+        /// <typeparam name="TKey">The type of the key to be used to fetch the cache entry.</typeparam>
+        /// <typeparam name="TResult">The type of the entry to be obtained from the cache.</typeparam>
+        /// <returns>The entry from the cache.</returns>
         public ICache<TKey, TResult> GetCache<TKey, TResult>() {
             return _cacheHolder.GetCache<TKey, TResult>(_component);
         }
diff --git a/src/Orchard/ContentManagement/ContentItem.cs b/src/Orchard/ContentManagement/ContentItem.cs
index a6f751230..b34545a2d 100644
--- a/src/Orchard/ContentManagement/ContentItem.cs
+++ b/src/Orchard/ContentManagement/ContentItem.cs
@@ -10,7 +10,6 @@ namespace Orchard.ContentManagement {
             _parts = new List<ContentPart>();
         }
 
-
         private readonly IList<ContentPart> _parts;
         ContentItem IContent.ContentItem { get { return this; } }
 
diff --git a/src/Orchard/ContentManagement/DefaultContentManager.cs b/src/Orchard/ContentManagement/DefaultContentManager.cs
index 7081bd87c..032e04756 100644
--- a/src/Orchard/ContentManagement/DefaultContentManager.cs
+++ b/src/Orchard/ContentManagement/DefaultContentManager.cs
@@ -128,7 +128,6 @@ namespace Orchard.ContentManagement {
                 return contentItem;
             }
 
-
             // allocate instance and set record property
             contentItem = New(versionRecord.ContentItemRecord.ContentType.Name);
             contentItem.VersionRecord = versionRecord;
@@ -398,13 +397,8 @@ namespace Orchard.ContentManagement {
 
             Handlers.Invoke(handler => handler.Indexed(indexContentContext), Logger);
         }
-
-        //public ISearchBuilder Search() {
-        //    return _indexManager.HasIndexProvider() 
-        //        ? _indexManager.GetSearchIndexProvider().CreateSearchBuilder("Search") 
-        //        : new NullSearchBuilder();
-        //}
     }
+
     class CallSiteCollection : ConcurrentDictionary<string, CallSite<Func<CallSite, object, object>>> {
         readonly Func<string, CallSite<Func<CallSite, object, object>>> _valueFactory;
 
diff --git a/src/Orchard/ContentManagement/Handlers/ContentItemBuilder.cs b/src/Orchard/ContentManagement/Handlers/ContentItemBuilder.cs
index 1d2498493..621bfb92a 100644
--- a/src/Orchard/ContentManagement/Handlers/ContentItemBuilder.cs
+++ b/src/Orchard/ContentManagement/Handlers/ContentItemBuilder.cs
@@ -2,12 +2,21 @@
 using Orchard.ContentManagement.MetaData.Models;
 
 namespace Orchard.ContentManagement.Handlers {
+    /// <summary>
+    /// Builds a contentitem based on its the type definition (<seealso cref="ContentTypeDefinition"/>).
+    /// </summary>
     public class ContentItemBuilder {
         private readonly ContentTypeDefinition _definition;
         private readonly ContentItem _item;
 
+        /// <summary>
+        /// Constructs a new Content Item Builder instance.
+        /// </summary>
+        /// <param name="definition">The definition for the content item to be built.</param>
         public ContentItemBuilder(ContentTypeDefinition definition) {
             _definition = definition;
+
+            // TODO: could / should be done on the build method ?
             _item = new ContentItem {
                 ContentType = definition.Name,
                 TypeDefinition = definition
@@ -18,23 +27,37 @@ namespace Orchard.ContentManagement.Handlers {
             return _item;
         }
 
+        /// <summary>
+        /// Welds a new part to the content item. If a part of the same type is already welded nothing is done.
+        /// </summary>
+        /// <typeparam name="TPart">The type of the part to be welded.</typeparam>
+        /// <returns>A new Content Item Builder with the item having the new part welded.</returns>
         public ContentItemBuilder Weld<TPart>() where TPart : ContentPart, new() {
-            var partName = typeof(TPart).Name;
 
-            var typePartDefinition = _definition.Parts.FirstOrDefault(p => p.PartDefinition.Name == partName);
-            if (typePartDefinition == null) {
-                typePartDefinition = new ContentTypePartDefinition(
-                    new ContentPartDefinition(partName),
-                    new SettingsDictionary());
+            // if the part hasn't be weld yet
+            if (_item.Parts.FirstOrDefault(part => part.GetType().Equals(typeof(TPart))) == null) {
+                var partName = typeof(TPart).Name;
 
-                var part = new TPart {
-                    TypePartDefinition = typePartDefinition
-                };
+                // obtain the type definition for the part
+                var typePartDefinition = _definition.Parts.FirstOrDefault(p => p.PartDefinition.Name == partName);
+                if (typePartDefinition == null) {
+                    // If the content item's type definition does not define the part; use an empty type definition.
+                    typePartDefinition = new ContentTypePartDefinition(
+                        new ContentPartDefinition(partName),
+                        new SettingsDictionary());
+                }
+
+                // build and weld the part
+                var part = new TPart { TypePartDefinition = typePartDefinition };
                 _item.Weld(part);
             }
+
             return this;
         }
 
+        /// <summary>
+        /// Welds a part to the content item.
+        /// </summary>
         public ContentItemBuilder Weld(ContentPart contentPart) {
             _item.Weld(contentPart);
             return this;
diff --git a/src/Orchard/ContentManagement/MetaData/Builders/ContentTypeDefinitionBuilder.cs b/src/Orchard/ContentManagement/MetaData/Builders/ContentTypeDefinitionBuilder.cs
index bc9630647..8092f7dd7 100644
--- a/src/Orchard/ContentManagement/MetaData/Builders/ContentTypeDefinitionBuilder.cs
+++ b/src/Orchard/ContentManagement/MetaData/Builders/ContentTypeDefinitionBuilder.cs
@@ -27,10 +27,6 @@ namespace Orchard.ContentManagement.MetaData.Builders {
             }
         }
 
-        private void Init(ContentTypeDefinition existing) {
-
-        }
-
         public ContentTypeDefinition Build() {
             return new ContentTypeDefinition(_name, _displayName, _parts, _settings);
         }
@@ -92,6 +88,5 @@ namespace Orchard.ContentManagement.MetaData.Builders {
                 return new ContentTypePartDefinition(_partDefinition, _settings);
             }
         }
-
     }
 }
diff --git a/src/Orchard/ContentManagement/MetaData/Builders/ContentTypePartDefinitionBuilder.cs b/src/Orchard/ContentManagement/MetaData/Builders/ContentTypePartDefinitionBuilder.cs
index 479443729..04c2d008e 100644
--- a/src/Orchard/ContentManagement/MetaData/Builders/ContentTypePartDefinitionBuilder.cs
+++ b/src/Orchard/ContentManagement/MetaData/Builders/ContentTypePartDefinitionBuilder.cs
@@ -17,4 +17,4 @@ namespace Orchard.ContentManagement.MetaData.Builders {
             return this;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Orchard/Environment/Extensions/ExtensionManager.cs b/src/Orchard/Environment/Extensions/ExtensionManager.cs
index 72e9f6b22..4b02ddd40 100644
--- a/src/Orchard/Environment/Extensions/ExtensionManager.cs
+++ b/src/Orchard/Environment/Extensions/ExtensionManager.cs
@@ -73,7 +73,6 @@ namespace Orchard.Environment.Extensions {
         }
 
         private Feature LoadFeature(FeatureDescriptor featureDescriptor) {
-            
             var extensionDescriptor = featureDescriptor.Extension;
             var featureId = featureDescriptor.Id;
             var extensionId = extensionDescriptor.Id;
@@ -94,6 +93,7 @@ namespace Orchard.Environment.Extensions {
                 Logger.Error(ex, "Error loading extension '{0}'", extensionId);
                 throw new OrchardException(T("Error while loading extension '{0}'.", extensionId), ex);
             }
+
             if (extensionEntry == null) {
                 // If the feature could not be compiled for some reason,
                 // return a "null" feature, i.e. a feature with no exported types.
diff --git a/src/Orchard/Mvc/OrchardControllerFactory.cs b/src/Orchard/Mvc/OrchardControllerFactory.cs
index 66342d054..e0330a326 100644
--- a/src/Orchard/Mvc/OrchardControllerFactory.cs
+++ b/src/Orchard/Mvc/OrchardControllerFactory.cs
@@ -42,6 +42,7 @@ namespace Orchard.Mvc {
                 return (Type) info.Metadata["ControllerType"];
             }
 
+            // fail as appropriate for MVC's expectations
             return null;
         }
 
@@ -52,6 +53,7 @@ namespace Orchard.Mvc {
                 return controller;
             }
 
+            // fail as appropriate for MVC's expectations
             return null;
         }