GenericModelBinder integration tests part 1

- Covers simple scenario for each model binder.
- Covers scenarios mixing a generic model binder with a greedy model
  binder.

test/Microsoft.AspNet.Mvc.IntegrationTests/ArrayModelBinderIntegrationTest.cs

@@ -0,0 +1,172 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Threading.Tasks;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.IntegrationTests
+{
+    // Integration tests targeting the behavior of the ArrayModelBinder with other model binders.
+    public class ArrayModelBinderIntegrationTest
+    {
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task ArrayModelBinder_BindsArrayOfSimpleType_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(int[])
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter[0]=10&parameter[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<int[]>(modelBindingResult.Model);
+            Assert.Equal(new int[] { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task ArrayModelBinder_BindsArrayOfSimpleType_WithExplicitPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                BindingInfo = new BindingInfo()
+                {
+                    BinderModelName = "prefix",
+                },
+                ParameterType = typeof(int[])
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?prefix[0]=10&prefix[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<int[]>(modelBindingResult.Model);
+            Assert.Equal(new int[] { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task ArrayModelBinder_BindsArrayOfSimpleType_EmptyPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(int[])
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?[0]=10&[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<int[]>(modelBindingResult.Model);
+            Assert.Equal(new int[] { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Empty collection should be created by the collection model binder #1579")]
+        public async Task ArrayModelBinder_BindsArrayOfSimpleType_NoData()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(int[])
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);  // This fails due to #1579
+            Assert.False(modelBindingResult.IsModelSet);
+            Assert.Empty(Assert.IsType<int[]>(modelBindingResult.Model));
+
+            Assert.Equal(0, modelState.Count);
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.IntegrationTests/CollectionModelBinderIntegrationTest.cs

@@ -0,0 +1,176 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.IntegrationTests
+{
+    // Integration tests targeting the behavior of the CollectionModelBinder with other model binders.
+    //
+    // Note that CollectionModelBinder handles both ICollection{T} and IList{T}
+    public class CollectionModelBinderIntegrationTest
+    {
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task CollectionModelBinder_BindsListOfSimpleType_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(List<int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter[0]=10&parameter[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<int>>(modelBindingResult.Model);
+            Assert.Equal(new List<int>() { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task CollectionModelBinder_BindsListOfSimpleType_WithExplicitPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                BindingInfo = new BindingInfo()
+                {
+                    BinderModelName = "prefix",
+                },
+                ParameterType = typeof(List<int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?prefix[0]=10&prefix[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<int>>(modelBindingResult.Model);
+            Assert.Equal(new List<int>() { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task CollectionModelBinder_BindsCollectionOfSimpleType_EmptyPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(ICollection<int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?[0]=10&[1]=11");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<int>>(modelBindingResult.Model);
+            Assert.Equal(new List<int> { 10, 11 }, model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "[0]").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "[1]").Value;
+            Assert.Equal("11", entry.Value.AttemptedValue);
+            Assert.Equal("11", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Empty collection should be created by the collection model binder #1579")]
+        public async Task CollectionModelBinder_BindsListOfSimpleType_NoData()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(List<int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);  // This fails due to #1579
+            Assert.False(modelBindingResult.IsModelSet);
+            Assert.Empty(Assert.IsType<List<int>>(modelBindingResult.Model));
+
+            Assert.Equal(0, modelState.Count);
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.IntegrationTests/DictionaryModelBinderIntegrationTest.cs

@@ -0,0 +1,173 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.IntegrationTests
+{
+    // Integration tests targeting the behavior of the DictionaryModelBinder with other model binders.
+    public class DictionaryModelBinderIntegrationTest
+    {
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task DictionaryModelBinder_BindsDictionaryOfSimpleType_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(Dictionary<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter[0].Key=key0&parameter[0].Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<Dictionary<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new Dictionary<string, int>() { { "key0", 10 } }, model);
+
+            Assert.Equal(2, modelState.Count); // Fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[0].Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "parameter[0].Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task DictionaryModelBinder_BindsDictionaryOfSimpleType_WithExplicitPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                BindingInfo = new BindingInfo()
+                {
+                    BinderModelName = "prefix",
+                },
+                ParameterType = typeof(Dictionary<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?prefix[0].Key=key0&prefix[0].Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<Dictionary<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new Dictionary<string, int>() { { "key0", 10 }, }, model);
+
+            Assert.Equal(2, modelState.Count); // Fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[0].Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "prefix[0].Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446, IsValue == false because of #2470")]
+        public async Task DictionaryModelBinder_BindsDictionaryOfSimpleType_EmptyPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(Dictionary<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?[0].Key=key0&[0].Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<Dictionary<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new Dictionary<string, int>() { { "key0", 10 }, }, model);
+
+            Assert.Equal(2, modelState.Count); // Fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid); // Fails due to #2470
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "[0].Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "[0].Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Empty collection should be created by the collection model binder #1579")]
+        public async Task DictionaryModelBinder_BindsDictionaryOfSimpleType_NoData()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(Dictionary<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);  // This fails due to #1579
+            Assert.False(modelBindingResult.IsModelSet);
+            Assert.Empty(Assert.IsType<Dictionary<string, int>>(modelBindingResult.Model));
+
+            Assert.Equal(0, modelState.Count);
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.IntegrationTests/GenericModelBinderIntegrationTest.cs

@@ -0,0 +1,206 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// 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.Threading.Tasks;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.IntegrationTests
+{
+    // Integration tests targeting the behavior of the GenericModelBinder and related classes
+    // with other model binders.
+    public class GenericModelBinderIntegrationTest
+    {
+        // This isn't an especially useful scenario - but it exercises what happens when you
+        // try to use a Collection of something that is bound greedily by model-type.
+        //
+        // In this example we choose IFormCollection - because IFormCollection has a dedicated
+        // model  binder.
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task GenericModelBinder_BindsCollection_ElementTypeFromGreedyModelBinder_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(List<IFormCollection>)
+            };
+
+            // Need to have a key here so that the GenericModelBinder will recurse to bind elements.
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter.index=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<IFormCollection>>(modelBindingResult.Model);
+            Assert.Equal(1, model.Count);
+            Assert.NotNull(model[0]);
+
+            Assert.Equal(0, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+
+        // This isn't an especially useful scenario - but it exercises what happens when you
+        // try to use a Collection of something that is bound greedily by model-type.
+        //
+        // In this example we choose IFormCollection - because IFormCollection has a dedicated
+        // model  binder.
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task GenericModelBinder_BindsCollection_ElementTypeFromGreedyModelBinder_EmptyPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(List<IFormCollection>)
+            };
+            // Need to have a key here so that the GenericModelBinder will recurse to bind elements.
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?index=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<IFormCollection>>(modelBindingResult.Model);
+            Assert.Equal(1, model.Count);
+            Assert.NotNull(model[0]);
+
+            Assert.Equal(0, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+
+        // This isn't an especially useful scenario - but it exercises what happens when you
+        // try to use a Collection of something that is bound greedily by model-type.
+        //
+        // In this example we choose IFormCollection - because IFormCollection has a dedicated
+        // model  binder.
+        [Fact(Skip = "Empty collection should be created by the collection model binder #1579")]
+        public async Task GenericModelBinder_BindsCollection_ElementTypeFromGreedyModelBinder_NoData()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(List<IFormCollection>)
+            };
+
+            // Without a key here so the GenericModelBinder will not recurse to bind elements.
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult); // This fails due to #1579
+            Assert.False(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<List<IFormCollection>>(modelBindingResult.Model);
+            Assert.Empty(model);
+        }
+
+        [BindAddress]
+        private class Address
+        {
+        }
+
+        private class BindAddressAttribute : Attribute, IBindingSourceMetadata
+        {
+            public static readonly BindingSource Source = new BindingSource(
+                "Address",
+                displayName: "Address",
+                isGreedy: true,
+                isFromRequest: true);
+
+            public BindingSource BindingSource
+            {
+                get
+                {
+                    return Source;
+                }
+            }
+        }
+
+        private class AddressBinder : BindingSourceModelBinder
+        {
+            public AddressBinder()
+                : base(BindAddressAttribute.Source)
+            {
+            }
+
+            protected override Task<ModelBindingResult> BindModelCoreAsync(ModelBindingContext bindingContext)
+            {
+                return Task.FromResult(new ModelBindingResult(
+                    new Address(),
+                    bindingContext.ModelName,
+                    isModelSet: true));
+            }
+        }
+
+        // This isn't an especially useful scenario - but it exercises what happens when you
+        // try to use a Collection of something that is bound greedily by binding source.
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task GenericModelBinder_BindsCollection_ElementTypeUsesGreedyModelBinder_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(Address[])
+            };
+
+            // Need to have a key here so that the GenericModelBinder will recurse to bind elements.
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter.index=0");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<Address[]>(modelBindingResult.Model);
+            Assert.Equal(1, model.Length);
+            Assert.NotNull(model[0]);
+
+            Assert.Equal(0, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.IntegrationTests/KeyValuePairModelBinderIntegrationTest.cs

@@ -0,0 +1,174 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.IntegrationTests
+{
+    // Integration tests targeting the behavior of the KeyValuePairModelBinder with other model binders.
+    public class KeyValuePairModelBinderIntegrationTest
+    {
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task KeyValuePairModelBinder_BindsKeyValuePairOfSimpleType_WithPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(KeyValuePair<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?parameter.Key=key0&parameter.Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<KeyValuePair<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new KeyValuePair<string, int>("key0", 10), model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "parameter.Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "parameter.Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task KeyValuePairModelBinder_BindsKeyValuePairOfSimpleType_WithExplicitPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                BindingInfo = new BindingInfo()
+                {
+                    BinderModelName = "prefix",
+                },
+                ParameterType = typeof(KeyValuePair<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?prefix.Key=key0&prefix.Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<KeyValuePair<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new KeyValuePair<string, int>("key0", 10), model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "prefix.Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "prefix.Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Extra ModelState key because of #2446")]
+        public async Task KeyValuePairModelBinder_BindsKeyValuePairOfSimpleType_EmptyPrefix_Success()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(KeyValuePair<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?Key=key0&Value=10");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult);
+            Assert.True(modelBindingResult.IsModelSet);
+
+            var model = Assert.IsType<KeyValuePair<string, int>>(modelBindingResult.Model);
+            Assert.Equal(new KeyValuePair<string, int>("key0", 10), model);
+
+            Assert.Equal(2, modelState.Count); // This fails due to #2446
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+
+            var entry = Assert.Single(modelState, kvp => kvp.Key == "Key").Value;
+            Assert.Equal("key0", entry.Value.AttemptedValue);
+            Assert.Equal("key0", entry.Value.RawValue);
+
+            entry = Assert.Single(modelState, kvp => kvp.Key == "Value").Value;
+            Assert.Equal("10", entry.Value.AttemptedValue);
+            Assert.Equal("10", entry.Value.RawValue);
+        }
+
+        [Fact(Skip = "Empty collection should be created by the collection model binder #1579")]
+        public async Task KeyValuePairModelBinder_BindsKeyValuePairOfSimpleType_NoData()
+        {
+            // Arrange
+            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
+            var parameter = new ParameterDescriptor()
+            {
+                Name = "parameter",
+                ParameterType = typeof(KeyValuePair<string, int>)
+            };
+
+            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(request =>
+            {
+                request.QueryString = new QueryString("?");
+            });
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
+
+            // Assert
+            Assert.NotNull(modelBindingResult); // This fails due to #1579
+            Assert.False(modelBindingResult.IsModelSet);
+
+            Assert.Equal(new int[0], modelBindingResult.Model);
+
+            Assert.Equal(0, modelState.Count);
+            Assert.Equal(0, modelState.ErrorCount);
+            Assert.True(modelState.IsValid);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.IntegrationTests/ModelBindingTestHelper.cs

@@ -12,11 +12,30 @@ namespace Microsoft.AspNet.Mvc.IntegrationTests
 {
     public static class ModelBindingTestHelper
     {
-        public static OperationBindingContext GetOperationBindingContext(Action<HttpRequest> updateRequest)
+        public static HttpContext GetHttpContext(
+            Action<HttpRequest> updateRequest = null,
+            Action<MvcOptions> updateOptions = null)
         {
-            var httpContext = ModelBindingTestHelper.GetHttpContext(updateRequest);
-            var actionBindingContext =
-              httpContext.RequestServices.GetRequiredService<IScopedInstance<ActionBindingContext>>().Value;
+            var httpContext = new DefaultHttpContext();
+
+            if (updateRequest != null)
+            {
+                updateRequest(httpContext.Request);
+            }
+
+            InitializeServices(httpContext, updateOptions);
+            return httpContext;
+        }
+
+        public static OperationBindingContext GetOperationBindingContext(
+            Action<HttpRequest> updateRequest = null,
+            Action<MvcOptions> updateOptions = null)
+        {
+            var httpContext = GetHttpContext(updateRequest, updateOptions);
+
+            var services = httpContext.RequestServices;
+            var actionBindingContext = services.GetRequiredService<IScopedInstance<ActionBindingContext>>().Value;
+
             return new OperationBindingContext()
             {
                 BodyBindingState = BodyBindingState.NotBodyBased,
@@ -40,13 +59,8 @@ namespace Microsoft.AspNet.Mvc.IntegrationTests
                     metadataProvider));
         }
 
-        public static HttpContext GetHttpContext(Action<HttpRequest> updateRequest)
+        private static void InitializeServices(HttpContext httpContext, Action<MvcOptions> updateOptions = null)
         {
-            var options = (new TestMvcOptions()).Options;
-            var httpContext = new DefaultHttpContext();
-
-            updateRequest(httpContext.Request);
-
             var serviceCollection = MvcServices.GetDefaultServices();
             httpContext.RequestServices = serviceCollection.BuildServiceProvider();
 
@@ -56,10 +70,15 @@ namespace Microsoft.AspNet.Mvc.IntegrationTests
                 httpContext.RequestServices.GetRequiredService<IScopedInstance<ActionContext>>();
             actionContextAccessor.Value = actionContext;
 
+            var options = new TestMvcOptions().Options;
+            if (updateOptions != null)
+            {
+                updateOptions(options);
+            }
+
             var actionBindingContextAccessor =
                 httpContext.RequestServices.GetRequiredService<IScopedInstance<ActionBindingContext>>();
             actionBindingContextAccessor.Value = GetActionBindingContext(options, actionContext);
-            return httpContext;
         }
 
         private static ActionBindingContext GetActionBindingContext(MvcOptions options, ActionContext actionContext)
@@ -82,4 +101,4 @@ namespace Microsoft.AspNet.Mvc.IntegrationTests
             };
         }
     }
-}
+}