Adjust tests to handle new `ViewDataDictionary` invariants

- ensure `ViewDataDictionary` constructors are not passed a `null` or
  `Mock.Of<IModelMetadataProvider>()` instance
 - `ViewDataDictionary` constructors always use the `IModelMetadataProvider`
- `viewData.ModelMetadata` now never `null`
- `ViewDataDictionary<int>.Model` no longer throws if read before it's written
- `ViewDataDictionary.ModelMetadata` now copied to new instances in fewer cases
 - e.g. don't use unusual `object` datatype with customized `ModelMetadata`

test/Microsoft.AspNet.Mvc.Core.Test/DefaultControllerActivatorTest.cs

@@ -22,7 +22,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             services.Setup(s => s.GetService(typeof(IUrlHelper)))
                     .Returns(Mock.Of<IUrlHelper>());
             services.Setup(s => s.GetService(typeof(IModelMetadataProvider)))
-                    .Returns(Mock.Of<IModelMetadataProvider>());
+                    .Returns(new EmptyModelMetadataProvider());
 
             var httpRequest = Mock.Of<HttpRequest>();
             var httpContext = new Mock<HttpContext>();
@@ -53,7 +53,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             // Arrange
             var services = new Mock<IServiceProvider>();
             services.Setup(s => s.GetService(typeof(IModelMetadataProvider)))
-                    .Returns(Mock.Of<IModelMetadataProvider>());
+                    .Returns(new EmptyModelMetadataProvider());
             services.Setup(s => s.GetService(typeof(ICompositeViewEngine)))
                     .Returns(Mock.Of<ICompositeViewEngine>());
             services.Setup(s => s.GetService(typeof(IUrlHelper)))
@@ -86,7 +86,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             services.Setup(s => s.GetService(typeof(IUrlHelper)))
                     .Returns(urlHelper);
             services.Setup(s => s.GetService(typeof(IModelMetadataProvider)))
-                    .Returns(Mock.Of<IModelMetadataProvider>());
+                    .Returns(new EmptyModelMetadataProvider());
 
             var httpContext = new Mock<HttpContext>();
             httpContext.SetupGet(c => c.RequestServices)
@@ -114,7 +114,7 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             services.Setup(s => s.GetService(typeof(IUrlHelper)))
                     .Returns(Mock.Of<IUrlHelper>());
             services.Setup(s => s.GetService(typeof(IModelMetadataProvider)))
-                    .Returns(Mock.Of<IModelMetadataProvider>());
+                    .Returns(new EmptyModelMetadataProvider());
 
             var httpContext = new Mock<HttpContext>();
             httpContext.SetupGet(c => c.Response)

test/Microsoft.AspNet.Mvc.Core.Test/DefaultViewComponentActivatorTests.cs

@@ -105,7 +105,7 @@ namespace Microsoft.AspNet.Mvc
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
             return new ViewContext(actionContext,
                                               Mock.Of<IView>(),
-                                              new ViewDataDictionary(Mock.Of<IModelMetadataProvider>()),
+                                              new ViewDataDictionary(new EmptyModelMetadataProvider()),
                                               TextWriter.Null);
         }
 

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperDisplayNameExtensionsTest.cs

@@ -86,7 +86,7 @@ namespace Microsoft.AspNet.Mvc.Core
                 new DataAnnotationsModelMetadataProvider(),
                 containerType: null,
                 modelAccessor: null,
-                modelType: typeof(object),
+                modelType: typeof(string), // Ensure FromStringExpression() doesn't ignore the ModelMetadata.
                 propertyName: propertyName);
 
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperLabelExtensionsTest.cs

@@ -101,7 +101,7 @@ namespace Microsoft.AspNet.Mvc.Core
                 new DataAnnotationsModelMetadataProvider(),
                 containerType: null,
                 modelAccessor: null,
-                modelType: typeof(object),
+                modelType: typeof(string), // Ensure FromStringExpression() doesn't ignore the ModelMetadata.
                 propertyName: propertyName);
 
             var helper = DefaultTemplatesUtilities.GetHtmlHelper();

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperNameExtensionsTest.cs

@@ -164,7 +164,7 @@ namespace Microsoft.AspNet.Mvc.Core
             // Only the ViewDataDictionary should do anything with metadata.
             provider.Verify(
                 m => m.GetMetadataForType(It.IsAny<Func<object>>(), typeof(DefaultTemplatesUtilities.ObjectTemplateModel)),
-                Times.Once);
+                Times.Exactly(2));
         }
 
         [Fact]
@@ -191,7 +191,7 @@ namespace Microsoft.AspNet.Mvc.Core
             // Only the ViewDataDictionary should do anything with metadata.
             provider.Verify(
                 m => m.GetMetadataForType(It.IsAny<Func<object>>(), typeof(DefaultTemplatesUtilities.ObjectTemplateModel)),
-                Times.Once);
+                Times.Exactly(2));
         }
 
         [Theory]

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/ViewContextTests.cs

@@ -1,6 +1,7 @@
 // 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 Microsoft.AspNet.Mvc.ModelBinding;
 using Xunit;
 
 namespace Microsoft.AspNet.Mvc.Rendering
@@ -12,8 +13,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
         {
             // Arrange (eventually passing null to these consturctors will throw)
             var context = new ViewContext(new ActionContext(null, null, null), view: null, viewData: null, writer: null);
-            var originalViewData = context.ViewData = new ViewDataDictionary(metadataProvider: null);
+            var originalViewData = context.ViewData = new ViewDataDictionary(metadataProvider: new EmptyModelMetadataProvider());
-            var replacementViewData = new ViewDataDictionary(metadataProvider: null);
+            var replacementViewData = new ViewDataDictionary(metadataProvider: new EmptyModelMetadataProvider());
 
             // Act
             context.ViewBag.Hello = "goodbye";

test/Microsoft.AspNet.Mvc.Core.Test/ViewComponentTests.cs

@@ -16,7 +16,7 @@ namespace Microsoft.AspNet.Mvc
             // Arrange
             var viewComponent = new TestViewComponent()
             {
-                ViewData = new ViewDataDictionary(metadataProvider: null),
+                ViewData = new ViewDataDictionary(metadataProvider: new EmptyModelMetadataProvider()),
             };
 
             // Act
@@ -35,7 +35,7 @@ namespace Microsoft.AspNet.Mvc
             // Arrange
             var viewComponent = new TestViewComponent()
             {
-                ViewData = new ViewDataDictionary(metadataProvider: null),
+                ViewData = new ViewDataDictionary(metadataProvider: new EmptyModelMetadataProvider()),
             };
 
             // Act

test/Microsoft.AspNet.Mvc.Core.Test/ViewDataDictionaryTest.cs

@@ -26,7 +26,7 @@ namespace Microsoft.AspNet.Mvc.Core
             Assert.NotNull(viewData.ModelState);
             Assert.NotNull(viewData.TemplateInfo);
             Assert.Null(viewData.Model);
-            Assert.Null(viewData.ModelMetadata);
+            Assert.NotNull(viewData.ModelMetadata);
             Assert.Equal(0, viewData.Count);
         }
 
@@ -44,7 +44,7 @@ namespace Microsoft.AspNet.Mvc.Core
             Assert.Same(modelState, viewData.ModelState);
             Assert.NotNull(viewData.TemplateInfo);
             Assert.Null(viewData.Model);
-            Assert.Null(viewData.ModelMetadata);
+            Assert.NotNull(viewData.ModelMetadata);
             Assert.Equal(0, viewData.Count);
         }
 
@@ -53,9 +53,14 @@ namespace Microsoft.AspNet.Mvc.Core
         {
             // Arrange
             var metadataProvider = new Mock<IModelMetadataProvider>();
-            metadataProvider.Setup(m => m.GetMetadataForType(It.IsAny<Func<object>>(), typeof(TestModel)))
+            metadataProvider
-                            .Returns(new EmptyModelMetadataProvider().GetMetadataForType(null, typeof(TestModel)))
+                .Setup(m => m.GetMetadataForType(It.IsAny<Func<object>>(), typeof(object)))
-                            .Verifiable();
+                .Returns(new EmptyModelMetadataProvider().GetMetadataForType(null, typeof(object)))
+                .Verifiable();
+            metadataProvider
+                .Setup(m => m.GetMetadataForType(It.IsAny<Func<object>>(), typeof(TestModel)))
+                .Returns(new EmptyModelMetadataProvider().GetMetadataForType(null, typeof(TestModel)))
+                .Verifiable();
             var modelState = new ModelStateDictionary();
             var viewData = new TestViewDataDictionary(metadataProvider.Object, modelState);
             var model = new TestModel();
@@ -134,7 +139,7 @@ namespace Microsoft.AspNet.Mvc.Core
             Assert.NotNull(viewData.ModelState);
             Assert.NotNull(viewData.TemplateInfo);
             Assert.Null(viewData.Model);
-            Assert.Null(viewData.ModelMetadata);
+            Assert.NotNull(viewData.ModelMetadata);
             Assert.Equal("value1", viewData["key1"]);
             Assert.IsType<CopyOnWriteDictionary<string, object>>(viewData.Data);
         }
@@ -148,45 +153,56 @@ namespace Microsoft.AspNet.Mvc.Core
             source["key1"] = "value1";
 
             // Act
-            var viewData = new ViewDataDictionary<int>(source, null);
+            var viewData = new ViewDataDictionary<int>(source, model: null);
 
             // Assert
             Assert.NotNull(viewData.ModelState);
             Assert.NotNull(viewData.TemplateInfo);
-            Assert.Throws<NullReferenceException>(() => viewData.Model);
+            Assert.Equal(0, viewData.Model);
             Assert.NotNull(viewData.ModelMetadata);
             Assert.Equal("value1", viewData["key1"]);
             Assert.IsType<CopyOnWriteDictionary<string, object>>(viewData.Data);
         }
 
+        public static TheoryData<Type, object> CopyModelMetadataData
+        {
+            get
+            {
+                // Instances in this data set must have exactly the same type as the corresponding Type. Otherwise
+                // the copy constructor ignores the source ModelMetadata.
+                return new TheoryData<Type, object>
+                {
+                    { typeof(int), 23 },
+                    { typeof(string), "hello" },
+                    { typeof(List<string>), new List<string>() },
+                    { typeof(string[]), new string[0] },
+                    { typeof(Dictionary<string, object>), new Dictionary<string, object>() },
+                };
+            }
+        }
+
         [Theory]
-        [InlineData(typeof(int))]
+        [MemberData(nameof(CopyModelMetadataData))]
-        [InlineData(typeof(string))]
+        public void CopyConstructors_CopyModelMetadata(Type type, object instance)
-        [InlineData(typeof(IEnumerable<string>))]
-        [InlineData(typeof(List<string>))]
-        [InlineData(typeof(string[]))]
-        [InlineData(typeof(Dictionary<string, object>))]
-        public void CopyConstructors_CopyModelMetadata(Type type)
         {
             // Arrange
             var metadataProvider = new EmptyModelMetadataProvider();
-            var metadata = metadataProvider.GetMetadataForType(() => null, type);
             var source = new ViewDataDictionary(metadataProvider)
             {
-                ModelMetadata = metadata,
+                Model = instance,
             };
 
             // Act
             var viewData1 = new ViewDataDictionary(source);
-            var viewData2 = new ViewDataDictionary(source, model: null);
+            var viewData2 = new ViewDataDictionary(source, model: instance);
 
             // Assert
-            Assert.Same(metadata, viewData1.ModelMetadata);
+            Assert.Same(source.ModelMetadata, viewData1.ModelMetadata);
-            Assert.Same(metadata, viewData2.ModelMetadata);
+            Assert.Same(source.ModelMetadata, viewData2.ModelMetadata);
         }
 
         [Fact]
-        public void CopyConstructors_IgnoreModelMetadata_IfForTypeObject()
+        public void CopyConstructors_CopyModelMetadata_ForTypeObject()
         {
             // Arrange
             var metadataProvider = new EmptyModelMetadataProvider();
@@ -201,8 +217,8 @@ namespace Microsoft.AspNet.Mvc.Core
             var viewData2 = new ViewDataDictionary(source, model: null);
 
             // Assert
-            Assert.Null(viewData1.ModelMetadata);
+            Assert.Same(metadata, viewData1.ModelMetadata);
-            Assert.Null(viewData2.ModelMetadata);
+            Assert.Same(metadata, viewData2.ModelMetadata);
         }
 
         [Theory]
@@ -240,6 +256,28 @@ namespace Microsoft.AspNet.Mvc.Core
             Assert.Equal(expectedType, viewData2.ModelMetadata.RealModelType);
         }
 
+        [Fact]
+        public void CopyConstructors_OverrideSourceMetadata_IfDeclaredTypeChanged()
+        {
+            // Arrange
+            var expectedType = typeof(string);
+            var metadataProvider = new EmptyModelMetadataProvider();
+            var source = new ViewDataDictionary<int>(metadataProvider);
+
+            // Act
+            var viewData1 = new ViewDataDictionary<string>(source);
+            var viewData2 = new ViewDataDictionary<string>(source, model: null);
+
+            // Assert
+            Assert.NotNull(viewData1.ModelMetadata);
+            Assert.Equal(expectedType, viewData1.ModelMetadata.ModelType);
+            Assert.Equal(expectedType, viewData1.ModelMetadata.RealModelType);
+
+            Assert.NotNull(viewData2.ModelMetadata);
+            Assert.Equal(expectedType, viewData2.ModelMetadata.ModelType);
+            Assert.Equal(expectedType, viewData2.ModelMetadata.RealModelType);
+        }
+
         public static TheoryData<object, string, object> Eval_EvaluatesExpressionsData
         {
             get

test/Microsoft.AspNet.Mvc.Razor.Test/RazorPageActivatorTest.cs

@@ -38,7 +38,7 @@ namespace Microsoft.AspNet.Mvc.Razor
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
             var viewContext = new ViewContext(actionContext,
                                               Mock.Of<IView>(),
-                                              new ViewDataDictionary(Mock.Of<IModelMetadataProvider>()),
+                                              new ViewDataDictionary(new EmptyModelMetadataProvider()),
                                               TextWriter.Null);
 
             // Act
@@ -68,7 +68,7 @@ namespace Microsoft.AspNet.Mvc.Razor
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
             var viewContext = new ViewContext(actionContext,
                                               Mock.Of<IView>(),
-                                              new ViewDataDictionary(Mock.Of<IModelMetadataProvider>()),
+                                              new ViewDataDictionary(new EmptyModelMetadataProvider()),
                                               TextWriter.Null);
 
             // Act and Assert
@@ -101,7 +101,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                        .Returns(serviceProvider.Object);
             var routeContext = new RouteContext(httpContext.Object);
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
-            var viewData = new ViewDataDictionary(Mock.Of<IModelMetadataProvider>())
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider())
             {
                 Model = new MyModel()
             };
@@ -136,7 +136,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                        .Returns(serviceProvider.Object);
             var routeContext = new RouteContext(httpContext.Object);
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
-            var viewData = new ViewDataDictionary<MyModel>(Mock.Of<IModelMetadataProvider>())
+            var viewData = new ViewDataDictionary<MyModel>(new EmptyModelMetadataProvider())
             {
                 Model = new MyModel()
             };
@@ -171,7 +171,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                        .Returns(serviceProvider.Object);
             var routeContext = new RouteContext(httpContext.Object);
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
-            var viewData = new ViewDataDictionary(Mock.Of<IModelMetadataProvider>());
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
             var viewContext = new ViewContext(actionContext,
                                               Mock.Of<IView>(),
                                               viewData,

test/Microsoft.AspNet.Mvc.Razor.Test/RazorPageCreateTagHelperTest.cs

@@ -88,7 +88,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                        .Returns(serviceProvider.Object);
             var routeContext = new RouteContext(httpContext.Object);
             var actionContext = new ActionContext(routeContext, new ActionDescriptor());
-            var viewData = new ViewDataDictionary(Mock.Of<IModelMetadataProvider>());
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
             var viewContext = new ViewContext(actionContext,
                                               Mock.Of<IView>(),
                                               viewData,

test/Microsoft.AspNet.Mvc.Razor.Test/RazorViewTest.cs

@@ -64,7 +64,7 @@ namespace Microsoft.AspNet.Mvc.Razor
         public async Task RenderAsync_AsPartial_ActivatesViews_WithThePassedInViewContext()
         {
             // Arrange
-            var viewData = new ViewDataDictionary(Mock.Of<IModelMetadataProvider>());
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider());
             var page = new TestableRazorPage(v =>
             {
                 // viewData is assigned to ViewContext by the activator
@@ -867,7 +867,7 @@ section-content-2";
             return new ViewContext(
                 actionContext,
                 view,
-                new ViewDataDictionary(Mock.Of<IModelMetadataProvider>()),
+                new ViewDataDictionary(new EmptyModelMetadataProvider()),
                 new StringWriter());
         }