From 200c9e21bdeaa6257d3f617b06e28f6d1bf42c69 Mon Sep 17 00:00:00 2001
From: Pranav K <prkrishn@hotmail.com>
Date: Mon, 20 May 2019 09:10:12 -0700
Subject: [PATCH] Use attributes for application part discovery (#10271)

* Use attributes for application part discovery

Fixes https://github.com/aspnet/AspNetCore/issues/4332
---
 eng/SharedFramework.External.props            |   3 -
 .../ref/Microsoft.AspNetCore.Mvc.Core.csproj  |   1 -
 ...osoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs |   9 +-
 .../ApplicationAssembliesProvider.cs          | 295 ----------
 .../ApplicationPartAttribute.cs               |  33 ++
 .../ApplicationPartManager.cs                 |  52 +-
 .../src/ApplicationParts/AssemblyPart.cs      |  29 +-
 .../src/Microsoft.AspNetCore.Mvc.Core.csproj  |   1 -
 .../ApplicationAssembliesProviderTest.cs      | 544 ------------------
 .../test/ApplicationParts/AssemblyPartTest.cs |  50 --
 .../Microsoft.AspNetCore.Mvc.Core.Test.csproj |   3 +-
 ...etCore.Mvc.Razor.RuntimeCompilation.csproj |   1 +
 ....Razor.RuntimeCompilation.netcoreapp3.0.cs |   7 +
 .../src/AssemblyPartExtensions.cs             |  38 ++
 ...etCore.Mvc.Razor.RuntimeCompilation.csproj |   1 +
 .../src/RazorReferenceManager.cs              |  22 +-
 .../test/AssemblyPartExtensionTest.cs         |  65 +++
 .../Microsoft.AspNetCore.Mvc.Testing.csproj   |   1 +
 .../Microsoft.AspNetCore.Mvc.Testing.csproj   |   1 +
 .../ApplicationAssembliesProviderTest.cs      |  58 --
 .../Properties/AssemblyInfo.cs                |   7 +
 21 files changed, 223 insertions(+), 998 deletions(-)
 delete mode 100644 src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationAssembliesProvider.cs
 create mode 100644 src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartAttribute.cs
 delete mode 100644 src/Mvc/Mvc.Core/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
 create mode 100644 src/Mvc/Mvc.Razor.RuntimeCompilation/src/AssemblyPartExtensions.cs
 create mode 100644 src/Mvc/Mvc.Razor.RuntimeCompilation/test/AssemblyPartExtensionTest.cs
 delete mode 100644 src/Mvc/Mvc/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
 create mode 100644 src/Mvc/test/WebSites/RazorPagesWebSite/Properties/AssemblyInfo.cs

diff --git a/eng/SharedFramework.External.props b/eng/SharedFramework.External.props
index b8cf631738..d735b0764f 100644
--- a/eng/SharedFramework.External.props
+++ b/eng/SharedFramework.External.props
@@ -56,9 +56,6 @@
     <ExternalAspNetCoreAppReference Include="System.Security.Cryptography.Xml"                             Version="$(SystemSecurityCryptographyXmlPackageVersion)" />
     <ExternalAspNetCoreAppReference Include="System.Threading.Channels"                                    Version="$(SystemThreadingChannelsPackageVersion)" />
 
-    <!-- Dependencies from dotnet/core-setup -->
-    <ExternalAspNetCoreAppReference Include="Microsoft.Extensions.DependencyModel"                         Version="$(MicrosoftExtensionsDependencyModelPackageVersion)" />
-
     <!--
       Transitive dependencies of other assemblies in the shared framework. These are listed separately and should not be included directly
       when setting `<Reference>`. These are listed for the purpose of tests and servicing builds only.
diff --git a/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.csproj b/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.csproj
index c77d73737f..d319a85c95 100644
--- a/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.csproj
+++ b/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.csproj
@@ -15,7 +15,6 @@
     <Reference Include="Microsoft.AspNetCore.Routing.Abstractions"  />
     <Reference Include="Microsoft.AspNetCore.Routing"  />
     <Reference Include="Microsoft.Extensions.DependencyInjection"  />
-    <Reference Include="Microsoft.Extensions.DependencyModel"  />
     <Reference Include="Microsoft.Extensions.FileProviders.Abstractions"  />
     <Reference Include="Microsoft.Extensions.Logging.Abstractions"  />
     <Reference Include="Microsoft.Extensions.ParameterDefaultValue.Sources"  />
diff --git a/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs b/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs
index 136cf9e1e0..3976060e0c 100644
--- a/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs
+++ b/src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs
@@ -1547,6 +1547,12 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
         protected ApplicationPart() { }
         public abstract string Name { get; }
     }
+    [System.AttributeUsageAttribute(System.AttributeTargets.Assembly, AllowMultiple=true)]
+    public sealed partial class ApplicationPartAttribute : System.Attribute
+    {
+        public ApplicationPartAttribute(string assemblyName) { }
+        public string AssemblyName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
+    }
     public abstract partial class ApplicationPartFactory
     {
         protected ApplicationPartFactory() { }
@@ -1560,13 +1566,12 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
         public System.Collections.Generic.IList<Microsoft.AspNetCore.Mvc.ApplicationParts.IApplicationFeatureProvider> FeatureProviders { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
         public void PopulateFeature<TFeature>(TFeature feature) { }
     }
-    public partial class AssemblyPart : Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPart, Microsoft.AspNetCore.Mvc.ApplicationParts.IApplicationPartTypeProvider, Microsoft.AspNetCore.Mvc.ApplicationParts.ICompilationReferencesProvider
+    public partial class AssemblyPart : Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPart, Microsoft.AspNetCore.Mvc.ApplicationParts.IApplicationPartTypeProvider
     {
         public AssemblyPart(System.Reflection.Assembly assembly) { }
         public System.Reflection.Assembly Assembly { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
         public override string Name { get { throw null; } }
         public System.Collections.Generic.IEnumerable<System.Reflection.TypeInfo> Types { get { throw null; } }
-        public System.Collections.Generic.IEnumerable<string> GetReferencePaths() { throw null; }
     }
     public partial class DefaultApplicationPartFactory : Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPartFactory
     {
diff --git a/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationAssembliesProvider.cs b/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationAssembliesProvider.cs
deleted file mode 100644
index c7169c7230..0000000000
--- a/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationAssembliesProvider.cs
+++ /dev/null
@@ -1,295 +0,0 @@
-// Copyright (c) .NET Foundation. 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.Linq;
-using System.Reflection;
-using Microsoft.AspNetCore.Mvc.Core;
-using Microsoft.Extensions.DependencyModel;
-
-namespace Microsoft.AspNetCore.Mvc.ApplicationParts
-{
-    internal class ApplicationAssembliesProvider
-    {
-        internal static HashSet<string> ReferenceAssemblies { get; } = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
-        {
-            // The deps file for the Microsoft.AspNetCore.App shared runtime is authored in a way where it does not say
-            // it depends on Microsoft.AspNetCore.Mvc even though it does. Explicitly list it so that referencing this runtime causes
-            // assembly discovery to work correctly.
-            "Microsoft.AspNetCore.App",
-            "Microsoft.AspNetCore.Mvc",
-            "Microsoft.AspNetCore.Mvc.Abstractions",
-            "Microsoft.AspNetCore.Mvc.ApiExplorer",
-            "Microsoft.AspNetCore.Mvc.Core",
-            "Microsoft.AspNetCore.Mvc.Cors",
-            "Microsoft.AspNetCore.Mvc.DataAnnotations",
-            "Microsoft.AspNetCore.Mvc.Formatters.Json",
-            "Microsoft.AspNetCore.Mvc.Formatters.Xml",
-            "Microsoft.AspNetCore.Mvc.Localization",
-            "Microsoft.AspNetCore.Mvc.NewtonsoftJson",
-            "Microsoft.AspNetCore.Mvc.Razor",
-            "Microsoft.AspNetCore.Mvc.RazorPages",
-            "Microsoft.AspNetCore.Mvc.TagHelpers",
-            "Microsoft.AspNetCore.Mvc.ViewFeatures",
-        };
-
-        /// <summary>
-        /// Returns an ordered list of application assemblies.
-        /// <para>
-        /// The order is as follows:
-        /// * Entry assembly
-        /// * Assemblies specified in the application's deps file ordered by name.
-        /// <para>
-        /// Each assembly is immediately followed by assemblies specified by annotated <see cref="RelatedAssemblyAttribute"/> ordered by name.
-        /// </para>
-        /// </para>
-        /// </summary>
-        public IEnumerable<Assembly> ResolveAssemblies(Assembly entryAssembly)
-        {
-            var dependencyContext = LoadDependencyContext(entryAssembly);
-
-            IEnumerable<AssemblyItem> assemblyItems;
-
-            if (dependencyContext == null || dependencyContext.CompileLibraries.Count == 0)
-            {
-                // If an application was built with PreserveCompilationContext = false, CompileLibraries will be empty and we
-                // can no longer reliably infer the dependency closure. In this case, treat it the same as a missing
-                // deps file.
-                assemblyItems = new[] { GetAssemblyItem(entryAssembly) };
-            }
-            else
-            {
-                assemblyItems = ResolveFromDependencyContext(dependencyContext);
-            }
-
-            assemblyItems = assemblyItems
-                .OrderBy(item => item.Assembly == entryAssembly ? 0 : 1)
-                .ThenBy(item => item.Assembly.FullName, StringComparer.Ordinal);
-
-            foreach (var item in assemblyItems)
-            {
-                yield return item.Assembly;
-
-                foreach (var associatedAssembly in item.RelatedAssemblies.Distinct().OrderBy(assembly => assembly.FullName, StringComparer.Ordinal))
-                {
-                    yield return associatedAssembly;
-                }
-            }
-        }
-
-        protected virtual DependencyContext LoadDependencyContext(Assembly assembly) => DependencyContext.Load(assembly);
-
-        private List<AssemblyItem> ResolveFromDependencyContext(DependencyContext dependencyContext)
-        {
-            var assemblyItems = new List<AssemblyItem>();
-            var relatedAssemblies = new Dictionary<Assembly, AssemblyItem>();
-
-            var candidateAssemblies = GetCandidateLibraries(dependencyContext)
-                .SelectMany(library => GetLibraryAssemblies(dependencyContext, library));
-
-            foreach (var assembly in candidateAssemblies)
-            {
-                var assemblyItem = GetAssemblyItem(assembly);
-                assemblyItems.Add(assemblyItem);
-
-                foreach (var relatedAssembly in assemblyItem.RelatedAssemblies)
-                {
-                    if (relatedAssemblies.TryGetValue(relatedAssembly, out var otherEntry))
-                    {
-                        var message = string.Join(
-                            Environment.NewLine,
-                            Resources.FormatApplicationAssembliesProvider_DuplicateRelatedAssembly(relatedAssembly.FullName),
-                            otherEntry.Assembly.FullName,
-                            assembly.FullName);
-
-                        throw new InvalidOperationException(message);
-                    }
-
-                    relatedAssemblies.Add(relatedAssembly, assemblyItem);
-                }
-            }
-
-            // Remove any top level assemblies that appear as an associated assembly.
-            assemblyItems.RemoveAll(item => relatedAssemblies.ContainsKey(item.Assembly));
-
-            return assemblyItems;
-        }
-
-        protected virtual IEnumerable<Assembly> GetLibraryAssemblies(DependencyContext dependencyContext, RuntimeLibrary runtimeLibrary)
-        {
-            foreach (var assemblyName in runtimeLibrary.GetDefaultAssemblyNames(dependencyContext))
-            {
-                var assembly = Assembly.Load(assemblyName);
-                yield return assembly;
-            }
-        }
-
-        protected virtual IReadOnlyList<Assembly> GetRelatedAssemblies(Assembly assembly)
-        {
-            // Do not require related assemblies to be available in the default code path.
-            return RelatedAssemblyAttribute.GetRelatedAssemblies(assembly, throwOnError: false);
-        }
-
-        private AssemblyItem GetAssemblyItem(Assembly assembly)
-        {
-            var relatedAssemblies = GetRelatedAssemblies(assembly);
-
-            // Ensure we don't have any cycles. A cycle could be formed if a related assembly points to the primary assembly.
-            foreach (var relatedAssembly in relatedAssemblies)
-            {
-                if (relatedAssembly.IsDefined(typeof(RelatedAssemblyAttribute)))
-                {
-                    throw new InvalidOperationException(
-                        Resources.FormatApplicationAssembliesProvider_RelatedAssemblyCannotDefineAdditional(relatedAssembly.FullName, assembly.FullName));
-                }
-            }
-
-            return new AssemblyItem(assembly, relatedAssemblies);
-        }
-
-        // Returns a list of libraries that references the assemblies in <see cref="ReferenceAssemblies"/>.
-        // By default it returns all assemblies that reference any of the primary MVC assemblies
-        // while ignoring MVC assemblies.
-        // Internal for unit testing
-        internal static IEnumerable<RuntimeLibrary> GetCandidateLibraries(DependencyContext dependencyContext)
-        {
-            // When using the Microsoft.AspNetCore.App shared runtimes, entries in the RuntimeLibraries
-            // get "erased" and it is no longer accurate to query to determine a library's dependency closure.
-            // We'll use CompileLibraries to calculate the dependency graph and runtime library to resolve assemblies to inspect.
-            var candidatesResolver = new CandidateResolver(dependencyContext.CompileLibraries, ReferenceAssemblies);
-            foreach (var library in dependencyContext.RuntimeLibraries)
-            {
-                if (candidatesResolver.IsCandidate(library))
-                {
-                    yield return library;
-                }
-            }
-        }
-
-        private class CandidateResolver
-        {
-            private readonly IDictionary<string, Dependency> _compileLibraries;
-
-            public CandidateResolver(IReadOnlyList<Library> compileLibraries, ISet<string> referenceAssemblies)
-            {
-                var compileLibrariesWithNoDuplicates = new Dictionary<string, Dependency>(StringComparer.OrdinalIgnoreCase);
-                foreach (var library in compileLibraries)
-                {
-                    if (compileLibrariesWithNoDuplicates.ContainsKey(library.Name))
-                    {
-                        throw new InvalidOperationException(Resources.FormatCandidateResolver_DifferentCasedReference(library.Name));
-                    }
-
-                    compileLibrariesWithNoDuplicates.Add(library.Name, CreateDependency(library, referenceAssemblies));
-                }
-
-                _compileLibraries = compileLibrariesWithNoDuplicates;
-            }
-
-            public bool IsCandidate(Library library)
-            {
-                var classification = ComputeClassification(library.Name);
-                return classification == DependencyClassification.ReferencesMvc;
-            }
-
-            private Dependency CreateDependency(Library library, ISet<string> referenceAssemblies)
-            {
-                var classification = DependencyClassification.Unknown;
-                if (referenceAssemblies.Contains(library.Name))
-                {
-                    classification = DependencyClassification.MvcReference;
-                }
-
-                return new Dependency(library, classification);
-            }
-
-            private DependencyClassification ComputeClassification(string dependency)
-            {
-                if (!_compileLibraries.ContainsKey(dependency))
-                {
-                    // Library does not have runtime dependency. Since we can't infer
-                    // anything about it's references, we'll assume it does not have a reference to Mvc.
-                    return DependencyClassification.DoesNotReferenceMvc;
-                }
-
-                var candidateEntry = _compileLibraries[dependency];
-                if (candidateEntry.Classification != DependencyClassification.Unknown)
-                {
-                    return candidateEntry.Classification;
-                }
-                else
-                {
-                    var classification = DependencyClassification.DoesNotReferenceMvc;
-                    foreach (var candidateDependency in candidateEntry.Library.Dependencies)
-                    {
-                        var dependencyClassification = ComputeClassification(candidateDependency.Name);
-                        if (dependencyClassification == DependencyClassification.ReferencesMvc ||
-                            dependencyClassification == DependencyClassification.MvcReference)
-                        {
-                            classification = DependencyClassification.ReferencesMvc;
-                            break;
-                        }
-                    }
-
-                    candidateEntry.Classification = classification;
-
-                    return classification;
-                }
-            }
-
-            private class Dependency
-            {
-                public Dependency(Library library, DependencyClassification classification)
-                {
-                    Library = library;
-                    Classification = classification;
-                }
-
-                public Library Library { get; }
-
-                public DependencyClassification Classification { get; set; }
-
-                public override string ToString()
-                {
-                    return $"Library: {Library.Name}, Classification: {Classification}";
-                }
-            }
-
-            private enum DependencyClassification
-            {
-                Unknown = 0,
-
-                /// <summary>
-                /// References (directly or transitively) one of the Mvc packages listed in
-                /// <see cref="ReferenceAssemblies"/>.
-                /// </summary>
-                ReferencesMvc = 1,
-
-                /// <summary>
-                /// Does not reference (directly or transitively) one of the Mvc packages listed by
-                /// <see cref="ReferenceAssemblies"/>.
-                /// </summary>
-                DoesNotReferenceMvc = 2,
-
-                /// <summary>
-                /// One of the references listed in <see cref="ReferenceAssemblies"/>.
-                /// </summary>
-                MvcReference = 3,
-            }
-        }
-
-        private readonly struct AssemblyItem
-        {
-            public AssemblyItem(Assembly assembly, IReadOnlyList<Assembly> associatedAssemblies)
-            {
-                Assembly = assembly;
-                RelatedAssemblies = associatedAssemblies;
-            }
-
-            public Assembly Assembly { get; }
-
-            public IReadOnlyList<Assembly> RelatedAssemblies { get; }
-        }
-    }
-}
diff --git a/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartAttribute.cs b/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartAttribute.cs
new file mode 100644
index 0000000000..e698396929
--- /dev/null
+++ b/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartAttribute.cs
@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    /// <summary>
+    /// Specifies an assembly to be added as an <see cref="ApplicationPart" />.
+    /// <para>
+    /// In the ordinary case, MVC will generate <see cref="ApplicationPartAttribute" />
+    /// instances on the entry assembly for each dependency that references MVC.
+    /// Each of these assemblies is treated as an <see cref="ApplicationPart" />.
+    /// </para>
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
+    public sealed class ApplicationPartAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ApplicationPartAttribute" />.
+        /// </summary>
+        /// <param name="assemblyName">The assembly name.</param>
+        public ApplicationPartAttribute(string assemblyName)
+        {
+            AssemblyName = assemblyName ?? throw new ArgumentNullException(nameof(assemblyName));
+        }
+
+        /// <summary>
+        /// Gets the assembly name.
+        /// </summary>
+        public string AssemblyName { get; }
+    }
+}
diff --git a/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartManager.cs b/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartManager.cs
index 99e1c608e1..0dd8681fe1 100644
--- a/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartManager.cs
+++ b/src/Mvc/Mvc.Core/src/ApplicationParts/ApplicationPartManager.cs
@@ -52,17 +52,55 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 
         internal void PopulateDefaultParts(string entryAssemblyName)
         {
-            var entryAssembly = Assembly.Load(new AssemblyName(entryAssemblyName));
-            var assembliesProvider = new ApplicationAssembliesProvider();
-            var applicationAssemblies = assembliesProvider.ResolveAssemblies(entryAssembly);
+            var assemblies = GetApplicationPartAssemblies(entryAssemblyName);
 
-            foreach (var assembly in applicationAssemblies)
+            var seenAssemblies = new HashSet<Assembly>();
+
+            foreach (var assembly in assemblies)
             {
-                var partFactory = ApplicationPartFactory.GetApplicationPartFactory(assembly);
-                foreach (var part in partFactory.GetApplicationParts(assembly))
+                if (!seenAssemblies.Add(assembly))
                 {
-                    ApplicationParts.Add(part);
+                    // "assemblies" may contain duplicate values, but we want unique ApplicationPart instances.
+                    // Note that we prefer using a HashSet over Distinct since the latter isn't
+                    // guaranteed to preserve the original ordering.
+                    continue;
                 }
+
+                var partFactory = ApplicationPartFactory.GetApplicationPartFactory(assembly);
+                foreach (var applicationPart in partFactory.GetApplicationParts(assembly))
+                {
+                    ApplicationParts.Add(applicationPart);
+                }
+            }
+        }
+
+        private static IEnumerable<Assembly> GetApplicationPartAssemblies(string entryAssemblyName)
+        {
+            var entryAssembly = Assembly.Load(new AssemblyName(entryAssemblyName));
+
+            // Use ApplicationPartAttribute to get the closure of direct or transitive dependencies
+            // that reference MVC.
+            var assembliesFromAttributes = entryAssembly.GetCustomAttributes<ApplicationPartAttribute>()
+                .Select(name => Assembly.Load(name.AssemblyName))
+                .OrderBy(assembly => assembly.FullName, StringComparer.Ordinal)
+                .SelectMany(GetAsemblyClosure);
+
+            // The SDK will not include the entry assembly as an application part. We'll explicitly list it
+            // and have it appear before all other assemblies \ ApplicationParts.
+            return GetAsemblyClosure(entryAssembly)
+                .Concat(assembliesFromAttributes);
+        }
+
+        private static IEnumerable<Assembly> GetAsemblyClosure(Assembly assembly)
+        {
+            yield return assembly;
+
+            var relatedAssemblies = RelatedAssemblyAttribute.GetRelatedAssemblies(assembly, throwOnError: false)
+                .OrderBy(assembly => assembly.FullName, StringComparer.Ordinal);
+
+            foreach (var relatedAssembly in relatedAssemblies)
+            {
+                yield return relatedAssembly;
             }
         }
     }
diff --git a/src/Mvc/Mvc.Core/src/ApplicationParts/AssemblyPart.cs b/src/Mvc/Mvc.Core/src/ApplicationParts/AssemblyPart.cs
index e3df2d6a14..ec2d2a76f0 100644
--- a/src/Mvc/Mvc.Core/src/ApplicationParts/AssemblyPart.cs
+++ b/src/Mvc/Mvc.Core/src/ApplicationParts/AssemblyPart.cs
@@ -5,17 +5,13 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
-using Microsoft.Extensions.DependencyModel;
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationParts
 {
     /// <summary>
     /// An <see cref="ApplicationPart"/> backed by an <see cref="System.Reflection.Assembly"/>.
     /// </summary>
-    public class AssemblyPart :
-        ApplicationPart,
-        IApplicationPartTypeProvider,
-        ICompilationReferencesProvider
+    public class AssemblyPart : ApplicationPart, IApplicationPartTypeProvider
     {
         /// <summary>
         /// Initializes a new <see cref="AssemblyPart"/> instance.
@@ -39,27 +35,6 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
         /// <inheritdoc />
         public IEnumerable<TypeInfo> Types => Assembly.DefinedTypes;
 
-        /// <inheritdoc />
-        public IEnumerable<string> GetReferencePaths()
-        {
-            if (Assembly.IsDynamic)
-            {
-                // Skip loading process for dynamic assemblies. This prevents DependencyContextLoader from reading the
-                // .deps.json file from either manifest resources or the assembly location, which will fail.
-                return Enumerable.Empty<string>();
-            }
-
-            var dependencyContext = DependencyContext.Load(Assembly);
-            if (dependencyContext != null)
-            {
-                return dependencyContext.CompileLibraries.SelectMany(library => library.ResolveReferencePaths());
-            }
-
-            // If an application has been compiled without preserveCompilationContext, return the path to the assembly
-            // as a reference. For runtime compilation, this will allow the compilation to succeed as long as it least
-            // one application part has been compiled with preserveCompilationContext and contains a super set of types
-            // required for the compilation to succeed.
-            return new[] { Assembly.Location };
-        }
+        
     }
 }
diff --git a/src/Mvc/Mvc.Core/src/Microsoft.AspNetCore.Mvc.Core.csproj b/src/Mvc/Mvc.Core/src/Microsoft.AspNetCore.Mvc.Core.csproj
index da787d60ca..fafac71bf7 100644
--- a/src/Mvc/Mvc.Core/src/Microsoft.AspNetCore.Mvc.Core.csproj
+++ b/src/Mvc/Mvc.Core/src/Microsoft.AspNetCore.Mvc.Core.csproj
@@ -42,7 +42,6 @@ Microsoft.AspNetCore.Mvc.RouteAttribute</Description>
     <Reference Include="Microsoft.AspNetCore.Routing.Abstractions" />
     <Reference Include="Microsoft.AspNetCore.Routing" />
     <Reference Include="Microsoft.Extensions.DependencyInjection" />
-    <Reference Include="Microsoft.Extensions.DependencyModel" />
     <Reference Include="Microsoft.Extensions.FileProviders.Abstractions" />
     <Reference Include="Microsoft.Extensions.Logging.Abstractions" />
   </ItemGroup>
diff --git a/src/Mvc/Mvc.Core/test/ApplicationParts/ApplicationAssembliesProviderTest.cs b/src/Mvc/Mvc.Core/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
deleted file mode 100644
index b7c040d42e..0000000000
--- a/src/Mvc/Mvc.Core/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
+++ /dev/null
@@ -1,544 +0,0 @@
-// Copyright (c) .NET Foundation. 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.Linq;
-using System.Reflection;
-using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.DependencyModel;
-using Newtonsoft.Json;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Mvc.ApplicationParts
-{
-    public class ApplicationAssembliesProviderTest
-    {
-        private static readonly Assembly ThisAssembly = typeof(ApplicationAssembliesProviderTest).Assembly;
-
-        [Fact]
-        public void ResolveAssemblies_ReturnsCurrentAssembly_IfNoDepsFileIsPresent()
-        {
-            // Arrange
-            var provider = new TestApplicationAssembliesProvider();
-
-            // Act
-            var result = provider.ResolveAssemblies(ThisAssembly);
-
-            // Assert
-            Assert.Equal(new[] { ThisAssembly }, result);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ReturnsCurrentAssembly_IfDepsFileDoesNotHaveAnyCompileLibraries()
-        {
-            // Arrange
-            var runtimeLibraries = new[]
-            {
-                GetRuntimeLibrary("MyApp", "Microsoft.AspNetCore.App"),
-                GetRuntimeLibrary("Microsoft.AspNetCore.App", "Microsoft.NETCore.App"),
-                GetRuntimeLibrary("Microsoft.NETCore.App"),
-                GetRuntimeLibrary("ClassLibrary"),
-            };
-            var dependencyContext = GetDependencyContext(compileLibraries: Array.Empty<CompilationLibrary>(), runtimeLibraries);
-            var provider = new TestApplicationAssembliesProvider
-            {
-                DependencyContext = dependencyContext,
-            };
-
-            // Act
-            var result = provider.ResolveAssemblies(ThisAssembly);
-
-            // Assert
-            Assert.Equal(new[] { ThisAssembly }, result);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ReturnsRelatedAssembliesOrderedByName()
-        {
-            // Arrange
-            var assembly1 = typeof(ApplicationAssembliesProvider).Assembly;
-            var assembly2 = typeof(IActionResult).Assembly;
-            var assembly3 = typeof(FactAttribute).Assembly;
-
-            var relatedAssemblies = new[] { assembly1, assembly2, assembly3 };
-            var provider = new TestApplicationAssembliesProvider
-            {
-                GetRelatedAssembliesDelegate = (assembly) => relatedAssemblies,
-            };
-
-            // Act
-            var result = provider.ResolveAssemblies(ThisAssembly);
-
-            // Assert
-            Assert.Equal(new[] { ThisAssembly, assembly2, assembly1, assembly3 }, result);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ReturnsLibrariesFromTheDepsFileThatReferenceMvc()
-        {
-            // Arrange
-            var mvcAssembly = typeof(IActionResult).Assembly;
-            var classLibrary = typeof(FactAttribute).Assembly;
-
-            var libraries = new Dictionary<string, string[]>
-            {
-                [ThisAssembly.GetName().Name] = new[] { mvcAssembly.GetName().Name, classLibrary.GetName().Name },
-                [mvcAssembly.GetName().Name] = Array.Empty<string>(),
-                [classLibrary.GetName().Name] = new[] { mvcAssembly.GetName().Name },
-            };
-
-            var dependencyContext = GetDependencyContext(libraries);
-
-            var provider = new TestApplicationAssembliesProvider
-            {
-                DependencyContext = dependencyContext,
-            };
-
-            // Act
-            var result = provider.ResolveAssemblies(ThisAssembly);
-
-            // Assert
-            Assert.Equal(new[] { ThisAssembly, classLibrary, }, result);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ReturnsRelatedAssembliesForLibrariesFromDepsFile()
-        {
-            // Arrange
-            var mvcAssembly = typeof(IActionResult).Assembly;
-            var classLibrary = typeof(object).Assembly;
-            var relatedPart = typeof(FactAttribute).Assembly;
-
-            var libraries = new Dictionary<string, string[]>
-            {
-                [ThisAssembly.GetName().Name] = new[] { relatedPart.GetName().Name, classLibrary.GetName().Name },
-                [classLibrary.GetName().Name] = new[] { mvcAssembly.GetName().Name },
-                [relatedPart.GetName().Name] = new[] { mvcAssembly.GetName().Name },
-                [mvcAssembly.GetName().Name] = Array.Empty<string>(),
-            };
-
-            var dependencyContext = GetDependencyContext(libraries);
-
-            var provider = new TestApplicationAssembliesProvider
-            {
-                DependencyContext = dependencyContext,
-                GetRelatedAssembliesDelegate = (assembly) =>
-                {
-                    if (assembly == classLibrary)
-                    {
-                        return new[] { relatedPart };
-                    }
-
-                    return Array.Empty<Assembly>();
-                },
-            };
-
-            // Act
-            var result = provider.ResolveAssemblies(ThisAssembly);
-
-            // Assert
-            Assert.Equal(new[] { ThisAssembly, classLibrary, relatedPart, }, result);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ThrowsIfRelatedAssemblyDefinesAdditionalRelatedAssemblies()
-        {
-            // Arrange
-            var expected = $"Assembly 'TestRelatedAssembly' declared as a related assembly by assembly '{ThisAssembly}' cannot define additional related assemblies.";
-            var assembly1 = typeof(ApplicationAssembliesProvider).Assembly;
-            var assembly2 = new TestAssembly();
-
-            var relatedAssemblies = new[] { assembly1, assembly2 };
-            var provider = new TestApplicationAssembliesProvider
-            {
-                GetRelatedAssembliesDelegate = (assembly) => relatedAssemblies,
-            };
-
-            // Act & Assert
-            var ex = Assert.Throws<InvalidOperationException>(() => provider.ResolveAssemblies(ThisAssembly).ToArray());
-            Assert.Equal(expected, ex.Message);
-        }
-
-        [Fact]
-        public void ResolveAssemblies_ThrowsIfMultipleAssembliesDeclareTheSameRelatedPart()
-        {
-            // Arrange
-            var mvcAssembly = typeof(IActionResult).Assembly;
-            var libraryAssembly1 = typeof(HttpContext).Assembly;
-            var libraryAssembly2 = typeof(JsonConverter).Assembly;
-            var relatedPart = typeof(FactAttribute).Assembly;
-            var expected = string.Join(
-                Environment.NewLine,
-                $"Each related assembly must be declared by exactly one assembly. The assembly '{relatedPart.FullName}' was declared as related assembly by the following:",
-                libraryAssembly1.FullName,
-                libraryAssembly2.FullName);
-
-            var libraries = new Dictionary<string, string[]>
-            {
-                [ThisAssembly.GetName().Name] = new[] { relatedPart.GetName().Name, libraryAssembly1.GetName().Name },
-                [libraryAssembly1.GetName().Name] = new[] { mvcAssembly.GetName().Name },
-                [libraryAssembly2.GetName().Name] = new[] { mvcAssembly.GetName().Name },
-                [mvcAssembly.GetName().Name] = Array.Empty<string>(),
-            };
-
-            var dependencyContext = GetDependencyContext(libraries);
-
-            var provider = new TestApplicationAssembliesProvider
-            {
-                DependencyContext = dependencyContext,
-                GetRelatedAssembliesDelegate = (assembly) =>
-                {
-                    if (assembly == libraryAssembly1 || assembly == libraryAssembly2)
-                    {
-                        return new[] { relatedPart };
-                    }
-
-                    return Array.Empty<Assembly>();
-                },
-            };
-
-            // Act & Assert
-            var ex = Assert.Throws<InvalidOperationException>(() => provider.ResolveAssemblies(ThisAssembly).ToArray());
-            Assert.Equal(expected, ex.Message);
-        }
-
-        [Fact]
-        public void CandidateResolver_ThrowsIfDependencyContextContainsDuplicateRuntimeLibraryNames()
-        {
-            // Arrange
-            var upperCaseLibrary = "Microsoft.AspNetCore.Mvc";
-            var mixedCaseLibrary = "microsoft.aspNetCore.mvc";
-
-            var libraries = new Dictionary<string, string[]>
-            {
-                [upperCaseLibrary] = Array.Empty<string>(),
-                [mixedCaseLibrary] = Array.Empty<string>(),
-            };
-            var dependencyContext = GetDependencyContext(libraries);
-
-            // Act
-            var exception = Assert.Throws<InvalidOperationException>(() => ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext).ToArray());
-
-            // Assert
-            Assert.Equal($"A duplicate entry for library reference {mixedCaseLibrary} was found. Please check that all package references in all projects use the same casing for the same package references.", exception.Message);
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_IgnoresMvcAssemblies()
-        {
-            // Arrange
-            var expected = GetRuntimeLibrary("SomeRandomAssembly", "Microsoft.AspNetCore.Mvc.Abstractions");
-            var runtimeLibraries = new[]
-            {
-                GetRuntimeLibrary("Microsoft.AspNetCore.Mvc.Core"),
-                GetRuntimeLibrary("Microsoft.AspNetCore.Mvc"),
-                GetRuntimeLibrary("Microsoft.AspNetCore.Mvc.Abstractions"),
-                expected,
-            };
-
-            var compileLibraries = new[]
-            {
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc.Core"),
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc.Abstractions"),
-                GetCompileLibrary("SomeRandomAssembly", "Microsoft.AspNetCore.Mvc.Abstractions"),
-            };
-            var dependencyContext = GetDependencyContext(compileLibraries, runtimeLibraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(new[] { expected }, candidates);
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_ReturnsRuntimeLibraries_IfCompileLibraryDependencyToMvcIsPresent()
-        {
-            // Arrange
-            // When an app is running against Microsoft.AspNetCore.App shared runtime or if the DependencyContext is queried
-            // from an app that's running on Microsoft.NETCore.App (e.g. in a unit testing scenario), the
-            // runtime library does not state that the app references Mvc whereas the compile library does. This test validates
-            // that we correctly recognize this scenario.
-            var expected = GetRuntimeLibrary("MyApp", "Microsoft.AspNetCore.App");
-            var runtimeLibraries = new[]
-            {
-                expected,
-                GetRuntimeLibrary("Microsoft.AspNetCore.App", "Microsoft.NETCore.App"),
-                GetRuntimeLibrary("Microsoft.NETCore.App"),
-            };
-
-            var compileLibraries = new[]
-            {
-                GetCompileLibrary("MyApp", "Microsoft.AspNetCore.App"),
-                GetCompileLibrary("Microsoft.AspNetCore.App", "Microsoft.AspNetCore.Mvc", "Microsoft.NETCore.App"),
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.NETCore.App"),
-            };
-            var dependencyContext = GetDependencyContext(compileLibraries, runtimeLibraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(new[] { expected }, candidates);
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_DoesNotThrow_IfLibraryDoesNotAppearAsCompileOrRuntimeLibrary()
-        {
-            // Arrange
-            var expected = GetRuntimeLibrary("MyApplication", "Microsoft.AspNetCore.Server.Kestrel", "Microsoft.AspNetCore.Mvc");
-            var compileLibraries = new[]
-            {
-                GetCompileLibrary("MyApplication", "Microsoft.AspNetCore.Server.Kestrel", "Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.AspNetCore.Server.Kestrel", "Libuv"),
-            };
-
-            var runtimeLibraries = new[]
-            {
-                expected,
-                GetRuntimeLibrary("Microsoft.AspNetCore.Server.Kestrel", "Libuv"),
-                GetRuntimeLibrary("Microsoft.AspNetCore.Mvc"),
-            };
-
-            var dependencyContext = GetDependencyContext(compileLibraries, runtimeLibraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext).ToList();
-
-            // Assert
-            Assert.Equal(new[] { expected }, candidates);
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_DoesNotThrow_IfCompileLibraryIsPresentButNotRuntimeLibrary()
-        {
-            // Arrange
-            var expected = GetRuntimeLibrary("MyApplication", "Microsoft.AspNetCore.Server.Kestrel", "Microsoft.AspNetCore.Mvc");
-            var compileLibraries = new[]
-            {
-                GetCompileLibrary("MyApplication", "Microsoft.AspNetCore.Server.Kestrel", "Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.AspNetCore.Mvc"),
-                GetCompileLibrary("Microsoft.AspNetCore.Server.Kestrel", "Libuv"),
-                GetCompileLibrary("Libuv"),
-            };
-
-            var runtimeLibraries = new[]
-            {
-                expected,
-                GetRuntimeLibrary("Microsoft.AspNetCore.Server.Kestrel", "Libuv"),
-                GetRuntimeLibrary("Microsoft.AspNetCore.Mvc"),
-            };
-
-            var dependencyContext = GetDependencyContext(compileLibraries, runtimeLibraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext).ToList();
-
-            // Assert
-            Assert.Equal(new[] { expected }, candidates);
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_ReturnsLibrariesReferencingAnyMvcAssembly()
-        {
-            // Arrange
-            var libraries = new Dictionary<string, string[]>
-            {
-                ["Foo"] = new[] { "Microsoft.AspNetCore.Mvc.Core" },
-                ["Bar"] = new[] { "Microsoft.AspNetCore.Mvc" },
-                ["Qux"] = new[] { "Not.Mvc.Assembly", "Unofficial.Microsoft.AspNetCore.Mvc" },
-                ["Baz"] = new[] { "Microsoft.AspNetCore.Mvc.Abstractions" },
-                ["Microsoft.AspNetCore.Mvc.Core"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["Not.Mvc.Assembly"] = Array.Empty<string>(),
-                ["Unofficial.Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc.Abstractions"] = Array.Empty<string>(),
-            };
-            var dependencyContext = GetDependencyContext(libraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(new[] { "Bar", "Baz", "Foo", }, candidates.Select(a => a.Name));
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_LibraryNameComparisonsAreCaseInsensitive()
-        {
-            // Arrange
-            var libraries = new Dictionary<string, string[]>
-            {
-                ["Foo"] = new[] { "MICROSOFT.ASPNETCORE.MVC.CORE" },
-                ["Bar"] = new[] { "microsoft.aspnetcore.mvc" },
-                ["Qux"] = new[] { "Not.Mvc.Assembly", "Unofficial.Microsoft.AspNetCore.Mvc" },
-                ["Baz"] = new[] { "mIcRoSoFt.AsPnEtCoRe.MvC.aBsTrAcTiOnS" },
-                ["Microsoft.AspNetCore.Mvc.Core"] = Array.Empty<string>(),
-                ["LibraryA"] = new[] { "LIBRARYB" },
-                ["LibraryB"] = new[] { "microsoft.aspnetcore.mvc" },
-                ["Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["Not.Mvc.Assembly"] = Array.Empty<string>(),
-                ["Unofficial.Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc.Abstractions"] = Array.Empty<string>(),
-            };
-            var dependencyContext = GetDependencyContext(libraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(new[] { "Bar", "Baz", "Foo", "LibraryA", "LibraryB" }, candidates.Select(a => a.Name));
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_ReturnsLibrariesWithTransitiveReferencesToAnyMvcAssembly()
-        {
-            // Arrange
-            var expectedLibraries = new[] { "Bar", "Baz", "Foo", "LibraryA", "LibraryB", "LibraryC", "LibraryE", "LibraryG", "LibraryH" };
-
-            var libraries = new Dictionary<string, string[]>
-            {
-                ["Foo"] = new[] { "Bar" },
-                ["Bar"] = new[] { "Microsoft.AspNetCore.Mvc" },
-                ["Qux"] = new[] { "Not.Mvc.Assembly", "Unofficial.Microsoft.AspNetCore.Mvc" },
-                ["Baz"] = new[] { "Microsoft.AspNetCore.Mvc.Abstractions" },
-                ["Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["Not.Mvc.Assembly"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc.Abstractions"] = Array.Empty<string>(),
-                ["Unofficial.Microsoft.AspNetCore.Mvc"] = Array.Empty<string>(),
-                ["LibraryA"] = new[] { "LibraryB" },
-                ["LibraryB"] = new[] { "LibraryC" },
-                ["LibraryC"] = new[] { "LibraryD", "Microsoft.AspNetCore.Mvc.Abstractions" },
-                ["LibraryD"] = Array.Empty<string>(),
-                ["LibraryE"] = new[] { "LibraryF", "LibraryG" },
-                ["LibraryF"] = Array.Empty<string>(),
-                ["LibraryG"] = new[] { "LibraryH" },
-                ["LibraryH"] = new[] { "LibraryI", "Microsoft.AspNetCore.Mvc" },
-                ["LibraryI"] = Array.Empty<string>(),
-            };
-            var dependencyContext = GetDependencyContext(libraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(expectedLibraries, candidates.Select(a => a.Name));
-        }
-
-        [Fact]
-        public void GetCandidateLibraries_SkipsMvcAssemblies()
-        {
-            // Arrange
-            var libraries = new Dictionary<string, string[]>
-            {
-                ["MvcSandbox"] = new[] { "Microsoft.AspNetCore.Mvc.Core", "Microsoft.AspNetCore.Mvc" },
-                ["Microsoft.AspNetCore.Mvc.Core"] = new[] { "Microsoft.AspNetCore.HttpAbstractions" },
-                ["Microsoft.AspNetCore.HttpAbstractions"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc"] = new[] { "Microsoft.AspNetCore.Mvc.Abstractions", "Microsoft.AspNetCore.Mvc.Core" },
-                ["Microsoft.AspNetCore.Mvc.Abstractions"] = Array.Empty<string>(),
-                ["Microsoft.AspNetCore.Mvc.TagHelpers"] = new[] { "Microsoft.AspNetCore.Mvc.Razor" },
-                ["Microsoft.AspNetCore.Mvc.Razor"] = Array.Empty<string>(),
-                ["ControllersAssembly"] = new[] { "Microsoft.AspNetCore.Mvc" },
-            };
-
-            var dependencyContext = GetDependencyContext(libraries);
-
-            // Act
-            var candidates = ApplicationAssembliesProvider.GetCandidateLibraries(dependencyContext);
-
-            // Assert
-            Assert.Equal(new[] { "ControllersAssembly", "MvcSandbox" }, candidates.Select(a => a.Name));
-        }
-
-        private class TestApplicationAssembliesProvider : ApplicationAssembliesProvider
-        {
-            public DependencyContext DependencyContext { get; set; }
-
-            public Func<Assembly, IReadOnlyList<Assembly>> GetRelatedAssembliesDelegate { get; set; } = (assembly) => Array.Empty<Assembly>();
-
-            protected override DependencyContext LoadDependencyContext(Assembly assembly) => DependencyContext;
-
-            protected override IReadOnlyList<Assembly> GetRelatedAssemblies(Assembly assembly) => GetRelatedAssembliesDelegate(assembly);
-
-            protected override IEnumerable<Assembly> GetLibraryAssemblies(DependencyContext dependencyContext, RuntimeLibrary runtimeLibrary)
-            {
-                var assemblyName = new AssemblyName(runtimeLibrary.Name);
-                yield return Assembly.Load(assemblyName);
-            }
-        }
-
-        private static DependencyContext GetDependencyContext(IDictionary<string, string[]> libraries)
-        {
-            var compileLibraries = new List<CompilationLibrary>();
-            var runtimeLibraries = new List<RuntimeLibrary>();
-
-            foreach (var kvp in libraries.OrderBy(kvp => kvp.Key, StringComparer.Ordinal))
-            {
-                var compileLibrary = GetCompileLibrary(kvp.Key, kvp.Value);
-                compileLibraries.Add(compileLibrary);
-
-                var runtimeLibrary = GetRuntimeLibrary(kvp.Key, kvp.Value);
-                runtimeLibraries.Add(runtimeLibrary);
-            }
-
-            return GetDependencyContext(compileLibraries, runtimeLibraries);
-        }
-
-        private static DependencyContext GetDependencyContext(
-            IReadOnlyList<CompilationLibrary> compileLibraries,
-            IReadOnlyList<RuntimeLibrary> runtimeLibraries)
-        {
-            var dependencyContext = new DependencyContext(
-                new TargetInfo("framework", "runtime", "signature", isPortable: true),
-                CompilationOptions.Default,
-                compileLibraries,
-                runtimeLibraries,
-                Enumerable.Empty<RuntimeFallbacks>());
-            return dependencyContext;
-        }
-
-        private static RuntimeLibrary GetRuntimeLibrary(string name, params string[] dependencyNames)
-        {
-            var dependencies = dependencyNames?.Select(d => new Dependency(d, "42.0.0")) ?? new Dependency[0];
-
-            return new RuntimeLibrary(
-                "package",
-                name,
-                "23.0.0",
-                "hash",
-                new RuntimeAssetGroup[0],
-                new RuntimeAssetGroup[0],
-                new ResourceAssembly[0],
-                dependencies: dependencies.ToArray(),
-                serviceable: true);
-        }
-
-        private static CompilationLibrary GetCompileLibrary(string name, params string[] dependencyNames)
-        {
-            var dependencies = dependencyNames?.Select(d => new Dependency(d, "42.0.0")) ?? new Dependency[0];
-
-            return new CompilationLibrary(
-                "package",
-                name,
-                "23.0.0",
-                "hash",
-                Enumerable.Empty<string>(),
-                dependencies: dependencies.ToArray(),
-                serviceable: true);
-        }
-
-        private class TestAssembly : Assembly
-        {
-            public override string FullName => "TestRelatedAssembly";
-
-            public override bool IsDefined(Type attributeType, bool inherit)
-            {
-                return attributeType == typeof(RelatedAssemblyAttribute);
-            }
-        }
-    }
-}
diff --git a/src/Mvc/Mvc.Core/test/ApplicationParts/AssemblyPartTest.cs b/src/Mvc/Mvc.Core/test/ApplicationParts/AssemblyPartTest.cs
index b922a9eff0..8350e24243 100644
--- a/src/Mvc/Mvc.Core/test/ApplicationParts/AssemblyPartTest.cs
+++ b/src/Mvc/Mvc.Core/test/ApplicationParts/AssemblyPartTest.cs
@@ -50,55 +50,5 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationParts
             // Act & Assert
             Assert.Equal(part.Assembly, assembly);
         }
-
-        [Fact]
-        public void GetReferencePaths_ReturnsReferencesFromDependencyContext_IfPreserveCompilationContextIsSet()
-        {
-            // Arrange
-            var assembly = GetType().GetTypeInfo().Assembly;
-            var part = new AssemblyPart(assembly);
-
-            // Act
-            var references = part.GetReferencePaths().ToList();
-
-            // Assert
-            Assert.Contains(assembly.Location, references);
-            Assert.Contains(
-                typeof(AssemblyPart).GetTypeInfo().Assembly.GetName().Name,
-                references.Select(Path.GetFileNameWithoutExtension));
-        }
-
-        [Fact]
-        public void GetReferencePaths_ReturnsAssemblyLocation_IfPreserveCompilationContextIsNotSet()
-        {
-            // Arrange
-            // src projects do not have preserveCompilationContext specified.
-            var assembly = typeof(AssemblyPart).GetTypeInfo().Assembly;
-            var part = new AssemblyPart(assembly);
-
-            // Act
-            var references = part.GetReferencePaths().ToList();
-
-            // Assert
-            var actual = Assert.Single(references);
-            Assert.Equal(assembly.Location, actual);
-        }
-
-        [Fact]
-        public void GetReferencePaths_ReturnsEmptySequenceForDynamicAssembly()
-        {
-            // Arrange
-            var name = new AssemblyName($"DynamicAssembly-{Guid.NewGuid()}");
-            var assembly = AssemblyBuilder.DefineDynamicAssembly(name,
-                AssemblyBuilderAccess.RunAndCollect);
-
-            var part = new AssemblyPart(assembly);
-
-            // Act
-            var references = part.GetReferencePaths().ToList();
-
-            // Assert
-            Assert.Empty(references);
-        }
     }
 }
diff --git a/src/Mvc/Mvc.Core/test/Microsoft.AspNetCore.Mvc.Core.Test.csproj b/src/Mvc/Mvc.Core/test/Microsoft.AspNetCore.Mvc.Core.Test.csproj
index b3f8e2c9a5..39df066d88 100644
--- a/src/Mvc/Mvc.Core/test/Microsoft.AspNetCore.Mvc.Core.Test.csproj
+++ b/src/Mvc/Mvc.Core/test/Microsoft.AspNetCore.Mvc.Core.Test.csproj
@@ -1,8 +1,7 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netcoreapp3.0</TargetFramework>
-    <PreserveCompilationContext>true</PreserveCompilationContext>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj b/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
index 6842a5c61a..0f66178b6d 100644
--- a/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
@@ -9,5 +9,6 @@
     <Reference Include="Microsoft.AspNetCore.Mvc.RazorPages"  />
     <Reference Include="Microsoft.AspNetCore.Razor.Runtime"  />
     <Reference Include="Microsoft.CodeAnalysis.Razor"  />
+    <Reference Include="Microsoft.Extensions.DependencyModel"  />
   </ItemGroup>
 </Project>
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.netcoreapp3.0.cs b/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.netcoreapp3.0.cs
index c5368df39d..a22420cffc 100644
--- a/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.netcoreapp3.0.cs
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/ref/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.netcoreapp3.0.cs
@@ -1,6 +1,13 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public static partial class AssemblyPartExtensions
+    {
+        public static System.Collections.Generic.IEnumerable<string> GetReferencePaths(this Microsoft.AspNetCore.Mvc.ApplicationParts.AssemblyPart assemblyPart) { throw null; }
+    }
+}
 namespace Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation
 {
     public partial class FileProviderRazorProjectItem : Microsoft.AspNetCore.Razor.Language.RazorProjectItem
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/src/AssemblyPartExtensions.cs b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/AssemblyPartExtensions.cs
new file mode 100644
index 0000000000..e3ceaa8817
--- /dev/null
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/AssemblyPartExtensions.cs
@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. 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.Linq;
+using Microsoft.Extensions.DependencyModel;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public static class AssemblyPartExtensions
+    {
+        /// <inheritdoc />
+        public static IEnumerable<string> GetReferencePaths(this AssemblyPart assemblyPart)
+        {
+            var assembly = assemblyPart?.Assembly ?? throw new ArgumentNullException(nameof(assemblyPart));
+
+            if (assembly.IsDynamic)
+            {
+                // Skip loading process for dynamic assemblies. This prevents DependencyContextLoader from reading the
+                // .deps.json file from either manifest resources or the assembly location, which will fail.
+                return Enumerable.Empty<string>();
+            }
+
+            var dependencyContext = DependencyContext.Load(assembly);
+            if (dependencyContext != null)
+            {
+                return dependencyContext.CompileLibraries.SelectMany(library => library.ResolveReferencePaths());
+            }
+
+            // If an application has been compiled without preserveCompilationContext, return the path to the assembly
+            // as a reference. For runtime compilation, this will allow the compilation to succeed as long as it least
+            // one application part has been compiled with preserveCompilationContext and contains a super set of types
+            // required for the compilation to succeed.
+            return new[] { assembly.Location };
+        }
+    }
+}
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/src/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
index e0775f860b..b75277126a 100644
--- a/src/Mvc/Mvc.Razor.RuntimeCompilation/src/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj
@@ -14,6 +14,7 @@
     <Reference Include="Microsoft.AspNetCore.Mvc.RazorPages" />
     <Reference Include="Microsoft.AspNetCore.Razor.Runtime" />
     <Reference Include="Microsoft.CodeAnalysis.Razor" />
+    <Reference Include="Microsoft.Extensions.DependencyModel" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/src/RazorReferenceManager.cs b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/RazorReferenceManager.cs
index ce0094a911..b672dbaff6 100644
--- a/src/Mvc/Mvc.Razor.RuntimeCompilation/src/RazorReferenceManager.cs
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/src/RazorReferenceManager.cs
@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. 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.IO;
 using System.Linq;
@@ -53,14 +52,21 @@ namespace Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation
         // For unit testing
         internal IEnumerable<string> GetReferencePaths()
         {
-            var referencesFromApplicationParts = _partManager
-                .ApplicationParts
-                .OfType<ICompilationReferencesProvider>()
-                .SelectMany(part => part.GetReferencePaths());
+            var referencePaths = new List<string>();
 
-            var referencePaths = referencesFromApplicationParts
-                .Concat(_options.AdditionalReferencePaths)
-                .Distinct(StringComparer.OrdinalIgnoreCase);
+            foreach (var part in _partManager.ApplicationParts)
+            {
+                if (part is ICompilationReferencesProvider compilationReferenceProvider)
+                {
+                    referencePaths.AddRange(compilationReferenceProvider.GetReferencePaths());
+                }
+                else if (part is AssemblyPart assemblyPart)
+                {
+                    referencePaths.AddRange(assemblyPart.GetReferencePaths());
+                }
+            }
+
+            referencePaths.AddRange(_options.AdditionalReferencePaths);
 
             return referencePaths;
         }
diff --git a/src/Mvc/Mvc.Razor.RuntimeCompilation/test/AssemblyPartExtensionTest.cs b/src/Mvc/Mvc.Razor.RuntimeCompilation/test/AssemblyPartExtensionTest.cs
new file mode 100644
index 0000000000..eb84d85728
--- /dev/null
+++ b/src/Mvc/Mvc.Razor.RuntimeCompilation/test/AssemblyPartExtensionTest.cs
@@ -0,0 +1,65 @@
+// Copyright (c) .NET Foundation. 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.IO;
+using System.Linq;
+using System.Reflection;
+using System.Reflection.Emit;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public class AssemblyPartExtensionTest
+    {
+        [Fact]
+        public void GetReferencePaths_ReturnsReferencesFromDependencyContext_IfPreserveCompilationContextIsSet()
+        {
+            // Arrange
+            var assembly = GetType().GetTypeInfo().Assembly;
+            var part = new AssemblyPart(assembly);
+
+            // Act
+            var references = part.GetReferencePaths().ToList();
+
+            // Assert
+            Assert.Contains(assembly.Location, references);
+            Assert.Contains(
+                typeof(AssemblyPart).GetTypeInfo().Assembly.GetName().Name,
+                references.Select(Path.GetFileNameWithoutExtension));
+        }
+
+        [Fact]
+        public void GetReferencePaths_ReturnsAssemblyLocation_IfPreserveCompilationContextIsNotSet()
+        {
+            // Arrange
+            // src projects do not have preserveCompilationContext specified.
+            var assembly = typeof(AssemblyPart).GetTypeInfo().Assembly;
+            var part = new AssemblyPart(assembly);
+
+            // Act
+            var references = part.GetReferencePaths().ToList();
+
+            // Assert
+            var actual = Assert.Single(references);
+            Assert.Equal(assembly.Location, actual);
+        }
+
+        [Fact]
+        public void GetReferencePaths_ReturnsEmptySequenceForDynamicAssembly()
+        {
+            // Arrange
+            var name = new AssemblyName($"DynamicAssembly-{Guid.NewGuid()}");
+            var assembly = AssemblyBuilder.DefineDynamicAssembly(name,
+                AssemblyBuilderAccess.RunAndCollect);
+
+            var part = new AssemblyPart(assembly);
+
+            // Act
+            var references = part.GetReferencePaths().ToList();
+
+            // Assert
+            Assert.Empty(references);
+        }
+    }
+}
diff --git a/src/Mvc/Mvc.Testing/ref/Microsoft.AspNetCore.Mvc.Testing.csproj b/src/Mvc/Mvc.Testing/ref/Microsoft.AspNetCore.Mvc.Testing.csproj
index 00d3840db3..b5e0c8a5df 100644
--- a/src/Mvc/Mvc.Testing/ref/Microsoft.AspNetCore.Mvc.Testing.csproj
+++ b/src/Mvc/Mvc.Testing/ref/Microsoft.AspNetCore.Mvc.Testing.csproj
@@ -8,6 +8,7 @@
     <Reference Include="Microsoft.AspNetCore.TestHost"  />
     <Reference Include="Microsoft.AspNetCore.Mvc.Core"  />
     <Reference Include="Microsoft.Extensions.HostFactoryResolver.Sources"  />
+    <Reference Include="Microsoft.Extensions.DependencyModel"  />
     <Reference Include="Microsoft.Extensions.Hosting"  />
   </ItemGroup>
 </Project>
diff --git a/src/Mvc/Mvc.Testing/src/Microsoft.AspNetCore.Mvc.Testing.csproj b/src/Mvc/Mvc.Testing/src/Microsoft.AspNetCore.Mvc.Testing.csproj
index 03f5bf0d8c..649663aaf7 100644
--- a/src/Mvc/Mvc.Testing/src/Microsoft.AspNetCore.Mvc.Testing.csproj
+++ b/src/Mvc/Mvc.Testing/src/Microsoft.AspNetCore.Mvc.Testing.csproj
@@ -13,6 +13,7 @@
     <Reference Include="Microsoft.AspNetCore.TestHost" />
     <Reference Include="Microsoft.AspNetCore.Mvc.Core" />
     <Reference Include="Microsoft.Extensions.HostFactoryResolver.Sources" />
+    <Reference Include="Microsoft.Extensions.DependencyModel" />
     <Reference Include="Microsoft.Extensions.Hosting" />
   </ItemGroup>
 
diff --git a/src/Mvc/Mvc/test/ApplicationParts/ApplicationAssembliesProviderTest.cs b/src/Mvc/Mvc/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
deleted file mode 100644
index 03d4ef3c73..0000000000
--- a/src/Mvc/Mvc/test/ApplicationParts/ApplicationAssembliesProviderTest.cs
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright (c) .NET Foundation. 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.Linq;
-using System.Reflection;
-using Microsoft.Extensions.DependencyModel;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Mvc.ApplicationParts
-{
-    public class ApplicationAssembliesProviderTest
-    {
-        private static readonly Assembly ThisAssembly = typeof(ApplicationAssembliesProviderTest).Assembly;
-
-        // This test verifies ApplicationAssembliesProviderTest.ReferenceAssemblies reflects the actual loadable assemblies
-        // of the libraries that Microsoft.AspNetCore.Mvc depends on.
-        // If we add or remove dependencies, this test should be changed together.
-        [Fact]
-        public void ReferenceAssemblies_ReturnsLoadableReferenceAssemblies()
-        {
-            // Arrange
-            var excludeAssemblies = new string[]
-            {
-                "Microsoft.AspNetCore.Mvc.Analyzers",
-                "Microsoft.AspNetCore.Mvc.Test",
-                "Microsoft.AspNetCore.Mvc.Core.TestCommon",
-            };
-
-            var additionalAssemblies = new[]
-            {
-                // The following assemblies are not reachable from Microsoft.AspNetCore.Mvc
-                "Microsoft.AspNetCore.App",
-                "Microsoft.AspNetCore.Mvc.NewtonsoftJson",
-                "Microsoft.AspNetCore.Mvc.Formatters.Xml",
-            };
-
-            var dependencyContextLibraries = DependencyContext.Load(ThisAssembly)
-                .CompileLibraries
-                .Where(r => r.Name.StartsWith("Microsoft.AspNetCore.Mvc", StringComparison.OrdinalIgnoreCase) &&
-                    !excludeAssemblies.Contains(r.Name, StringComparer.OrdinalIgnoreCase))
-                .Select(r => r.Name);
-
-            var expected = dependencyContextLibraries
-                .Concat(additionalAssemblies)
-                .Distinct(StringComparer.OrdinalIgnoreCase)
-                .OrderBy(p => p, StringComparer.OrdinalIgnoreCase);
-
-            // Act
-            var referenceAssemblies = ApplicationAssembliesProvider
-                .ReferenceAssemblies
-                .OrderBy(p => p, StringComparer.OrdinalIgnoreCase);
-
-            // Assert
-            Assert.Equal(expected, referenceAssemblies, StringComparer.OrdinalIgnoreCase);
-        }
-    }
-}
diff --git a/src/Mvc/test/WebSites/RazorPagesWebSite/Properties/AssemblyInfo.cs b/src/Mvc/test/WebSites/RazorPagesWebSite/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000000..bd7ade2f84
--- /dev/null
+++ b/src/Mvc/test/WebSites/RazorPagesWebSite/Properties/AssemblyInfo.cs
@@ -0,0 +1,7 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+
+// This will eventually be codegened, but it's fine for duplicates to be present
+[assembly: ApplicationPart("RazorPagesClassLibrary")]
\ No newline at end of file