Add ModelState entries for greedy and type-matching model binders

- part II of II for #2445
- `FormCollectionModelBinder` is an exception because container is not user-provided
 - no `ModelState` entry added
- enable tests that #2445 was blocking
 - fix these and other tests expecting different `ModelState` entries
- simplify logic in `FormFileModelBinder`

`ValueProviderResult`
- remove `protected` setters and parameterless constructor
 - no scenario for their use in subclasses; however `ConvertTo()` remains `virtual`
- add single-parameter constructor
 - use in most of the greedy and type-matching model binders
- add doc comments throughout class

nits:
- use new `ValueProviderResult` constructor in many existing tests
- `""` -> `string.Empty` and `vpr` -> `valueProviderResult` in `ValueProviderResultTest`
- improve some test names in `BodyValidationIntegrationTests`
- do not check `Message` of a Json.NET `Exception`

src/Microsoft.AspNet.Mvc.Abstractions/ModelBinding/ValueProviderResult.cs

@@ -12,45 +12,83 @@
 
 namespace Microsoft.AspNet.Mvc.ModelBinding
 {
+    /// <summary>
+    /// Result of an <see cref="IValueProvider.GetValueAsync"/> operation.
+    /// </summary>
     public class ValueProviderResult
     {
         private static readonly CultureInfo _staticCulture = CultureInfo.InvariantCulture;
-        private CultureInfo _instanceCulture;
 
-        // default constructor so that subclassed types can set the properties themselves
-        protected ValueProviderResult()
+        /// <summary>
+        /// Instantiates a new instance of the <see cref="ValueProviderResult"/> class with given
+        /// <paramref name="rawValue"/>. Initializes <see cref="Culture"/> to
+        /// <see cref="CultureInfo.InvariantCulture"/>.
+        /// </summary>
+        /// <param name="rawValue">The <see cref="RawValue"/> value of the new instance.</param>
+        public ValueProviderResult(object rawValue)
+            : this(rawValue, attemptedValue: null, culture: _staticCulture)
         {
         }
 
+        /// <summary>
+        /// Instantiates a new instance of the <see cref="ValueProviderResult"/> class with given
+        /// <paramref name="rawValue"/>, <paramref name="attemptedValue"/>, and <paramref name="culture"/>.
+        /// </summary>
+        /// <param name="rawValue">The <see cref="RawValue"/> value of the new instance.</param>
+        /// <param name="attemptedValue">The <see cref="AttemptedValue"/> value of the new instance.</param>
+        /// <param name="culture">The <see cref="Culture"/> value of the new instance.</param>
         public ValueProviderResult(object rawValue, string attemptedValue, CultureInfo culture)
         {
             RawValue = rawValue;
             AttemptedValue = attemptedValue;
-            Culture = culture;
+            Culture = culture ?? _staticCulture;
         }
 
-        public string AttemptedValue { get; protected set; }
-
-        public CultureInfo Culture
-        {
-            get
-            {
-                if (_instanceCulture == null)
-                {
-                    _instanceCulture = _staticCulture;
-                }
-                return _instanceCulture;
-            }
-            protected set { _instanceCulture = value; }
-        }
-
-        public object RawValue { get; protected set; }
-
+        /// <summary>
+        /// <see cref="string"/> conversion of <see cref="RawValue"/>.
+        /// </summary>
+        /// <remarks>
+        /// Used in helpers that generate <c>&lt;textarea&gt;</c> elements as well as some error messages.
+        /// </remarks>
+        public string AttemptedValue { get; }
+
+        /// <summary>
+        /// <see cref="CultureInfo"/> to use in <see cref="ConvertTo(Type)"/> or
+        /// <see cref="ConvertTo(Type, CultureInfo)"/> if passed <see cref="CultureInfo"/> is <c>null</c>.
+        /// </summary>
+        public CultureInfo Culture { get; }
+
+        /// <summary>
+        /// The provided <see cref="object"/>.
+        /// </summary>
+        public object RawValue { get; }
+
+        /// <summary>
+        /// Converts <see cref="RawValue"/> to the given <paramref name="type"/>. Uses <see cref="Culture"/> for
+        /// <see cref="TypeConverter"/> operations.
+        /// </summary>
+        /// <param name="type">The target <see cref="Type"/> of the conversion.</param>
+        /// <returns>
+        /// <see cref="RawValue"/> converted to the given <paramref name="type"/>. <c>null</c> if the conversion fails.
+        /// </returns>
         public object ConvertTo(Type type)
         {
             return ConvertTo(type, culture: null);
         }
 
+        /// <summary>
+        /// Converts <see cref="RawValue"/> to the given <paramref name="type"/> using the given
+        /// <paramref name="culture"/>.
+        /// </summary>
+        /// <param name="type">The target <see cref="Type"/> of the conversion.</param>
+        /// <param name="culture">
+        /// The <see cref="CultureInfo"/> to use for <see cref="TypeConverter"/> operations. Uses
+        /// <see cref="Culture"/> if this parameter is <c>null</c>.
+        /// </param>
+        /// <returns>
+        /// <see cref="RawValue"/> converted to the given <paramref name="type"/> using the given
+        /// <paramref name="culture"/>. <c>null</c> if the conversion fails.
+        /// </returns>
         public virtual object ConvertTo([NotNull] Type type, CultureInfo culture)
         {
             var value = RawValue;

src/Microsoft.AspNet.Mvc.Core/ModelBinding/BodyModelBinder.cs

@@ -66,6 +66,8 @@ protected async override Task<ModelBindingResult> BindModelCoreAsync(
                     return new ModelBindingResult(modelBindingKey);
                 }
 
+                var valueProviderResult = new ValueProviderResult(rawValue: model);
+                bindingContext.ModelState.SetModelValue(modelBindingKey, valueProviderResult);
 
                 var validationNode = new ModelValidationNode(modelBindingKey, bindingContext.ModelMetadata, model)
                 {

src/Microsoft.AspNet.Mvc.Core/ModelBinding/ByteArrayModelBinder.cs

@@ -21,17 +21,17 @@ public async Task<ModelBindingResult> BindModelAsync([NotNull] ModelBindingConte
                 return null;
             }
 
-            var valueProviderResult = await bindingContext.ValueProvider.GetValueAsync(bindingContext.ModelName);
-
             // Check for missing data case 1: There was no <input ... /> element containing this data.
+            var valueProviderResult = await bindingContext.ValueProvider.GetValueAsync(bindingContext.ModelName);
             if (valueProviderResult == null)
             {
                 return new ModelBindingResult(model: null, key: bindingContext.ModelName, isModelSet: false);
             }
 
-            var value = valueProviderResult.AttemptedValue;
+            bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);
 
             // Check for missing data case 2: There was an <input ... /> element but it was left blank.
+            var value = valueProviderResult.AttemptedValue;
             if (string.IsNullOrEmpty(value))
             {
                 return new ModelBindingResult(model: null, key: bindingContext.ModelName, isModelSet: false);

src/Microsoft.AspNet.Mvc.Core/ModelBinding/FormCollectionModelBinder.cs

@@ -25,7 +25,7 @@ public async Task<ModelBindingResult> BindModelAsync([NotNull] ModelBindingConte
                 return null;
             }
 
-            object model = null;
+            object model;
             var request = bindingContext.OperationBindingContext.HttpContext.Request;
             if (request.HasFormContentType)
             {
@@ -36,8 +36,7 @@ public async Task<ModelBindingResult> BindModelAsync([NotNull] ModelBindingConte
                 }
                 else
                 {
-                    var formValuesLookup = form.ToDictionary(p => p.Key,
-                                                             p => p.Value);
+                    var formValuesLookup = form.ToDictionary(p => p.Key, p => p.Value);
                     model = new FormCollection(formValuesLookup, form.Files);
                 }
             }

src/Microsoft.AspNet.Mvc.Core/ModelBinding/FormFileModelBinder.cs

@@ -4,7 +4,9 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+#if DNXCORE50
 using System.Reflection;
+#endif
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http;
 using Microsoft.Framework.Internal;
@@ -20,33 +22,38 @@ public class FormFileModelBinder : IModelBinder
         /// <inheritdoc />
         public async Task<ModelBindingResult> BindModelAsync([NotNull] ModelBindingContext bindingContext)
         {
+            object value;
             if (bindingContext.ModelType == typeof(IFormFile))
             {
                 var postedFiles = await GetFormFilesAsync(bindingContext);
-                var value = postedFiles.FirstOrDefault();
-                var validationNode =
-                    new ModelValidationNode(bindingContext.ModelName, bindingContext.ModelMetadata, value);
-                return new ModelBindingResult(
-                    value,
-                    bindingContext.ModelName,
-                    isModelSet: value != null,
-                    validationNode: validationNode);
+                value = postedFiles.FirstOrDefault();
             }
-            else if (typeof(IEnumerable<IFormFile>).GetTypeInfo().IsAssignableFrom(
-                    bindingContext.ModelType.GetTypeInfo()))
+            else if (typeof(IEnumerable<IFormFile>).IsAssignableFrom(bindingContext.ModelType))
             {
                 var postedFiles = await GetFormFilesAsync(bindingContext);
-                var value = ModelBindingHelper.ConvertValuesToCollectionType(bindingContext.ModelType, postedFiles);
-                var validationNode =
+                value = ModelBindingHelper.ConvertValuesToCollectionType(bindingContext.ModelType, postedFiles);
+            }
+            else
+            {
+                // This binder does not support the requested type.
+                return null;
+            }
+
+            ModelValidationNode validationNode = null;
+            if (value != null)
+            {
+                validationNode =
                     new ModelValidationNode(bindingContext.ModelName, bindingContext.ModelMetadata, value);
-                return new ModelBindingResult(
-                    value,
-                    bindingContext.ModelName,
-                    isModelSet: value != null,
-                    validationNode: validationNode);
+
+                var valueProviderResult = new ValueProviderResult(rawValue: value);
+                bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);
             }
 
-            return null;
+            return new ModelBindingResult(
+                value,
+                bindingContext.ModelName,
+                isModelSet: value != null,
+                validationNode: validationNode);
         }
 
         private async Task<List<IFormFile>> GetFormFilesAsync(ModelBindingContext bindingContext)

src/Microsoft.AspNet.Mvc.Core/ModelBinding/HeaderModelBinder.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Globalization;
 #if DNXCORE50
 using System.Reflection;
 #endif
@@ -59,6 +60,10 @@ protected override Task<ModelBindingResult> BindModelCoreAsync([NotNull] ModelBi
                     bindingContext.ModelName,
                     bindingContext.ModelMetadata,
                     model);
+
+                var attemptedValue = (model as string) ?? request.Headers.Get(headerName);
+                var valueProviderResult = new ValueProviderResult(model, attemptedValue, CultureInfo.InvariantCulture);
+                bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);
             }
 
             return Task.FromResult(

test/Microsoft.AspNet.Mvc.Abstractions.Test/ModelBinding/ModelStateDictionaryTest.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using System.Globalization;
 using Microsoft.Framework.Internal;
 using Xunit;
@@ -75,7 +74,7 @@ public void MarkFieldSkipped_Throws_IfStateIsInvalid()
 
             // Act
             var exception = Assert.Throws<InvalidOperationException>(() => source.MarkFieldSkipped("key"));
-            
+
             // Assert
             Assert.Equal(
                 "A field previously marked invalid should not be marked skipped.",
@@ -138,7 +137,7 @@ public void MarkFieldValid_Throws_IfStateIsInvalid()
 
             // Act
             var exception = Assert.Throws<InvalidOperationException>(() => source.MarkFieldValid("key"));
-            
+
             // Assert
             Assert.Equal(
                 "A field previously marked invalid should not be marked valid.",
@@ -278,7 +277,7 @@ public void GetFieldValidationState_ReturnsValidIfModelStateDoesNotContainErrors
             // Arrange
             var validState = new ModelState
             {
-                Value = new ValueProviderResult(null, null, null),
+                Value = new ValueProviderResult(rawValue: null),
                 ValidationState = ModelValidationState.Valid
             };
             var msd = new ModelStateDictionary
@@ -317,7 +316,7 @@ public void GetFieldValidationState_IndexedPrefix_ReturnsValidIfModelStateDoesNo
             // Arrange
             var validState = new ModelState
             {
-                Value = new ValueProviderResult(null, null, null),
+                Value = new ValueProviderResult(rawValue: null),
                 ValidationState = ModelValidationState.Valid
             };
             var msd = new ModelStateDictionary