Add a PagesOption type that allows configuring the root for Page file discovery

Fixes #5785

samples/MvcSandbox/MvcSandbox.csproj

@@ -1,8 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
   <Import Project="..\..\build\common.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net452;netcoreapp1.1</TargetFrameworks>
+    <TargetFrameworks>netcoreapp1.1;net452</TargetFrameworks>
     <TargetFrameworks Condition="'$(OS)' != 'Windows_NT'">netcoreapp1.1</TargetFrameworks>
   </PropertyGroup>
 

src/Microsoft.AspNetCore.Mvc.Razor/Internal/DefaultRazorProject.cs

@@ -6,7 +6,6 @@ using System.Collections.Generic;
 using System.IO;
 using Microsoft.AspNetCore.Razor.Evolution;
 using Microsoft.Extensions.FileProviders;
-using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.Internal
 {
@@ -29,21 +28,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
 
         public override IEnumerable<RazorProjectItem> EnumerateItems(string path)
         {
-            if (path == null)
+            EnsureValidPath(path);
-            {
+            return EnumerateFiles(_provider.GetDirectoryContents(path), path, prefix: string.Empty);
-                throw new ArgumentNullException(nameof(path));
-            }
-
-            if (path.Length == 0 || path[0] != '/')
-            {
-                throw new ArgumentException(Resources.RazorProject_PathMustStartWithForwardSlash);
-            }
-
-            return EnumerateFiles(_provider.GetDirectoryContents(path), path, "");
         }
 
-        public virtual IChangeToken Watch(string pattern) => _provider.Watch(pattern);
-
         private IEnumerable<RazorProjectItem> EnumerateFiles(IDirectoryContents directory, string basePath, string prefix)
         {
             if (directory.Exists)
@@ -53,7 +41,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
                     if (file.IsDirectory)
                     {
                         var relativePath = prefix + "/" + file.Name;
-                        var subDirectory = _provider.GetDirectoryContents(relativePath);
+                        var subDirectory = _provider.GetDirectoryContents(JoinPath(basePath, relativePath));
                         var children = EnumerateFiles(subDirectory, basePath, relativePath);
                         foreach (var child in children)
                         {
@@ -67,5 +55,21 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
                 }
             }
         }
+
+        private static string JoinPath(string path1, string path2)
+        {
+            var hasTrailingSlash = path1.EndsWith("/", StringComparison.Ordinal);
+            var hasLeadingSlash = path2.StartsWith("/", StringComparison.Ordinal);
+            if (hasLeadingSlash && hasTrailingSlash)
+            {
+                return path1 + path2.Substring(1);
+            }
+            else if (hasLeadingSlash || hasTrailingSlash)
+            {
+                return path1 + path2;
+            }
+
+            return path1 + "/" + path2;
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.RazorPages/Infrastructure/PageActionDescriptorProvider.cs

@@ -33,7 +33,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
         public void OnProvidersExecuting(ActionDescriptorProviderContext context)
         {
-            foreach (var item in _project.EnumerateItems("/"))
+            foreach (var item in _project.EnumerateItems(_pagesOptions.RootDirectory))
             {
                 if (item.Filename.StartsWith("_"))
                 {
@@ -66,7 +66,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
         private void AddActionDescriptors(IList<ActionDescriptor> actions, RazorProjectItem item, string template)
         {
             var model = new PageApplicationModel(item.CombinedPath, item.PathWithoutExtension);
-            var routePrefix = item.BasePath == "/" ? item.PathWithoutExtension : item.BasePath + item.PathWithoutExtension;
+            var routePrefix = item.PathWithoutExtension;
             model.Selectors.Add(CreateSelectorModel(routePrefix, template));
 
             if (string.Equals(IndexFileName, item.Filename, StringComparison.OrdinalIgnoreCase))

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageActionDescriptorChangeProvider.cs

@@ -1,22 +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 Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
-using Microsoft.AspNetCore.Razor.Evolution;
+using Microsoft.Extensions.FileProviders;
+using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 {
     public class PageActionDescriptorChangeProvider : IActionDescriptorChangeProvider
     {
-        private readonly RazorProject _razorProject;
+        private readonly IFileProvider _fileProvider;
+        private readonly string _searchPattern;
 
-        public PageActionDescriptorChangeProvider(RazorProject razorProject)
+        public PageActionDescriptorChangeProvider(
+            IRazorViewEngineFileProviderAccessor fileProviderAccessor,
+            IOptions<RazorPagesOptions> razorPagesOptions)
         {
-            _razorProject = razorProject;
+            if (fileProviderAccessor == null)
+            {
+                throw new ArgumentNullException(nameof(fileProviderAccessor));
+            }
+
+            if (razorPagesOptions == null)
+            {
+                throw new ArgumentNullException(nameof(razorPagesOptions));
+            }
+
+            _fileProvider = fileProviderAccessor.FileProvider;
+            _searchPattern = razorPagesOptions.Value.RootDirectory.TrimEnd('/') +  "/**/*.cshtml";
         }
 
-        public IChangeToken GetChangeToken() => ((DefaultRazorProject)_razorProject).Watch("**/*.cshtml");
+        public IChangeToken GetChangeToken() => _fileProvider.Watch(_searchPattern);
     }
 }

src/Microsoft.AspNetCore.Mvc.RazorPages/Properties/Resources.Designer.cs

@@ -91,7 +91,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
         }
 
         /// <summary>
-        /// Unsupported handler method type '{0}'.
+        /// Unsupported handler method return type '{0}'.
         /// </summary>
         internal static string UnsupportedHandlerMethodType
         {
@@ -99,13 +99,29 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
         }
 
         /// <summary>
-        /// Unsupported handler method type '{0}'.
+        /// Unsupported handler method return type '{0}'.
         /// </summary>
         internal static string FormatUnsupportedHandlerMethodType(object p0)
         {
             return string.Format(CultureInfo.CurrentCulture, GetString("UnsupportedHandlerMethodType"), p0);
         }
 
+        /// <summary>
+        /// Path must be an application relative path that starts with a forward slash '/'.
+        /// </summary>
+        internal static string PathMustBeAnAppRelativePath
+        {
+            get { return GetString("PathMustBeAnAppRelativePath"); }
+        }
+
+        /// <summary>
+        /// Path must be an application relative path that starts with a forward slash '/'.
+        /// </summary>
+        internal static string FormatPathMustBeAnAppRelativePath()
+        {
+            return GetString("PathMustBeAnAppRelativePath");
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

src/Microsoft.AspNetCore.Mvc.RazorPages/RazorPagesOptions.cs

@@ -12,10 +12,34 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
     /// </summary>
     public class RazorPagesOptions
     {
+        private string _root = "/";
+
         /// <summary>
         /// Gets a list of <see cref="IPageApplicationModelConvention"/> instances that will be applied to
         /// the <see cref="PageModel"/> when discovering Razor Pages.
         /// </summary>
         public IList<IPageApplicationModelConvention> Conventions { get; } = new List<IPageApplicationModelConvention>();
+
+        /// <summary>
+        /// Application relative path used as the root of discovery for Razor Page files.
+        /// </summary>
+        public string RootDirectory
+        {
+            get => _root;
+            set
+            {
+                if (string.IsNullOrEmpty(value))
+                {
+                    throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(value));
+                }
+
+                if (value[0] != '/')
+                {
+                    throw new ArgumentException(Resources.PathMustBeAnAppRelativePath, nameof(value));
+                }
+
+                _root = value;
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.RazorPages/Resources.resx

@@ -135,4 +135,7 @@
   <data name="UnsupportedHandlerMethodType" xml:space="preserve">
     <value>Unsupported handler method return type '{0}'.</value>
   </data>
+  <data name="PathMustBeAnAppRelativePath" xml:space="preserve">
+    <value>Path must be an application relative path that starts with a forward slash '/'.</value>
+  </data>
 </root>

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RazorPagesTest.cs

@@ -35,6 +35,8 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
         public async Task HelloWorld_CanGetContent()
         {
             // Arrange
+            // Note: If the route in this test case ever changes, the negative test case
+            // RazorPagesWithBasePathTest.PageOutsideBasePath_IsNotRouteable needs to be updated too.
             var request = new HttpRequestMessage(HttpMethod.Get, "http://localhost/HelloWorld");
 
             // Act

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RazorPagesWithBasePathTest.cs

@@ -0,0 +1,117 @@
+// 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.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.FunctionalTests
+{
+    public class RazorPagesWithBasePathTest : IClassFixture<MvcTestFixture<RazorPagesWebSite.StartupWithBasePath>>
+    {
+        public RazorPagesWithBasePathTest(MvcTestFixture<RazorPagesWebSite.StartupWithBasePath> fixture)
+        {
+            Client = fixture.Client;
+        }
+
+        public HttpClient Client { get; }
+
+        [Fact]
+        public async Task PageOutsideBasePath_IsNotRouteable()
+        {
+            // Act
+            var response = await Client.GetAsync("/HelloWorld");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+        }
+
+        [Fact]
+        public async Task IndexAtBasePath_IsRouteableAtRoot()
+        {
+            // Act
+            var response = await Client.GetAsync("/");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from /Index", content.Trim());
+        }
+
+        [Fact]
+        public async Task IndexAtBasePath_IsRouteableViaIndex()
+        {
+            // Act
+            var response = await Client.GetAsync("/Index");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from /Index", content.Trim());
+        }
+
+        [Fact]
+        public async Task IndexInSubdirectory_IsRouteableViaDirectoryName()
+        {
+            // Act
+            var response = await Client.GetAsync("/Admin/Index");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from /Admin/Index", content.Trim());
+        }
+
+        [Fact]
+        public async Task PageWithRouteTemplateInSubdirectory_IsRouteable()
+        {
+            // Act
+            var response = await Client.GetAsync("/Admin/RouteTemplate/1/MyRouteSuffix/");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from /Admin/RouteTemplate 1", content.Trim());
+        }
+
+        [Fact]
+        public async Task PageWithRouteTemplateInSubdirectory_IsRouteable_WithOptionalParameters()
+        {
+            // Act
+            var response = await Client.GetAsync("/Admin/RouteTemplate/my-user-id/MyRouteSuffix/4");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from /Admin/RouteTemplate my-user-id 4", content.Trim());
+        }
+
+        [Fact]
+        public async Task AuthConvention_IsAppliedOnBasePathRelativePaths_ForFiles()
+        {
+            // Act
+            var response = await Client.GetAsync("/Conventions/Auth");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
+            Assert.Equal("/Login?ReturnUrl=%2FConventions%2FAuth", response.Headers.Location.PathAndQuery);
+        }
+
+        [Fact]
+        public async Task AuthConvention_IsAppliedOnBasePathRelativePaths_For_Folders()
+        {
+            // Act
+            var response = await Client.GetAsync("/Conventions/AuthFolder");
+
+            // Assert
+            Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
+            Assert.Equal("/Login?ReturnUrl=%2FConventions%2FAuthFolder", response.Headers.Location.PathAndQuery);
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.Razor.Test/Internal/DefaultRazorProjectTest.cs

@@ -0,0 +1,129 @@
+// 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.Linq;
+using Microsoft.Extensions.FileProviders;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.Internal
+{
+    public class DefaultRazorProjectTest
+    {
+        [Fact]
+        public void EnumerateFiles_ReturnsEmptySequenceIfNoCshtmlFilesArePresent()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var file1 = fileProvider.AddFile("File1.txt", "content");
+            var file2 = fileProvider.AddFile("File2.js", "content");
+            fileProvider.AddDirectoryContent("/", new IFileInfo[] { file1, file2 });
+
+            var razorProject = new DefaultRazorProject(fileProvider);
+
+            // Act
+            var razorFiles = razorProject.EnumerateItems("/");
+
+            // Assert
+            Assert.Empty(razorFiles);
+        }
+
+        [Fact]
+        public void EnumerateFiles_ReturnsCshtmlFiles()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var file1 = fileProvider.AddFile("File1.cshtml", "content");
+            var file2 = fileProvider.AddFile("File2.js", "content");
+            var file3 = fileProvider.AddFile("File3.cshtml", "content");
+            fileProvider.AddDirectoryContent("/", new IFileInfo[] { file1, file2, file3 });
+
+            var razorProject = new DefaultRazorProject(fileProvider);
+
+            // Act
+            var razorFiles = razorProject.EnumerateItems("/");
+
+            // Assert
+            Assert.Collection(razorFiles.OrderBy(f => f.Path),
+                file => Assert.Equal("/File1.cshtml", file.Path),
+                file => Assert.Equal("/File3.cshtml", file.Path));
+        }
+
+        [Fact]
+        public void EnumerateFiles_IteratesOverAllCshtmlUnderRoot()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var directory1 = new TestDirectoryFileInfo
+            {
+                Name = "Level1-Dir1",
+            };
+            var file1 = fileProvider.AddFile("File1.cshtml", "content");
+            var directory2 = new TestDirectoryFileInfo
+            {
+                Name = "Level1-Dir2",
+            };
+            fileProvider.AddDirectoryContent("/", new IFileInfo[] { directory1, file1, directory2 });
+
+            var file2 = fileProvider.AddFile("Level1-Dir1/File2.cshtml", "content");
+            var file3 = fileProvider.AddFile("Level1-Dir1/File3.cshtml", "content");
+            var file4 = fileProvider.AddFile("Level1-Dir1/File4.txt", "content");
+            var directory3 = new TestDirectoryFileInfo
+            {
+                Name = "Level2-Dir1"
+            };
+            fileProvider.AddDirectoryContent("/Level1-Dir1", new IFileInfo[] { file2, directory3, file3, file4 });
+            var file5 = fileProvider.AddFile("Level1-Dir2/File5.cshtml", "content");
+            fileProvider.AddDirectoryContent("/Level1-Dir2", new IFileInfo[] { file5 });
+            fileProvider.AddDirectoryContent("/Level1/Level2", new IFileInfo[0]);
+            var razorProject = new DefaultRazorProject(fileProvider);
+
+            // Act
+            var razorFiles = razorProject.EnumerateItems("/");
+
+            // Assert
+            Assert.Collection(razorFiles.OrderBy(f => f.Path),
+                file => Assert.Equal("/File1.cshtml", file.Path),
+                file => Assert.Equal("/Level1-Dir1/File2.cshtml", file.Path),
+                file => Assert.Equal("/Level1-Dir1/File3.cshtml", file.Path),
+                file => Assert.Equal("/Level1-Dir2/File5.cshtml", file.Path));
+        }
+
+        [Fact]
+        public void EnumerateFiles_IteratesOverAllCshtmlUnderPath()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var directory1 = new TestDirectoryFileInfo
+            {
+                Name = "Level1-Dir1",
+            };
+            var file1 = fileProvider.AddFile("File1.cshtml", "content");
+            var directory2 = new TestDirectoryFileInfo
+            {
+                Name = "Level1-Dir2",
+            };
+            fileProvider.AddDirectoryContent("/", new IFileInfo[] { directory1, file1, directory2 });
+
+            var file2 = fileProvider.AddFile("Level1-Dir1/File2.cshtml", "content");
+            var file3 = fileProvider.AddFile("Level1-Dir1/File3.cshtml", "content");
+            var file4 = fileProvider.AddFile("Level1-Dir1/File4.txt", "content");
+            var directory3 = new TestDirectoryFileInfo
+            {
+                Name = "Level2-Dir1"
+            };
+            fileProvider.AddDirectoryContent("/Level1-Dir1", new IFileInfo[] { file2, directory3, file3, file4 });
+            var file5 = fileProvider.AddFile("Level1-Dir2/File5.cshtml", "content");
+            fileProvider.AddDirectoryContent("/Level1-Dir2", new IFileInfo[] { file5 });
+            fileProvider.AddDirectoryContent("/Level1/Level2", new IFileInfo[0]);
+            var razorProject = new DefaultRazorProject(fileProvider);
+
+            // Act
+            var razorFiles = razorProject.EnumerateItems("/Level1-Dir1");
+
+            // Assert
+            Assert.Collection(razorFiles.OrderBy(f => f.Path),
+                file => Assert.Equal("/File2.cshtml", file.Path),
+                file => Assert.Equal("/File3.cshtml", file.Path));
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Infrastructure/PageActionDescriptorProviderTest.cs

@@ -95,6 +95,75 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             Assert.Equal("Test/Home", descriptor.AttributeRouteInfo.Template);
         }
 
+        [Fact]
+        public void GetDescriptors_GeneratesRouteTemplate()
+        {
+            // Arrange
+            var razorProject = new Mock<RazorProject>(MockBehavior.Strict);
+            razorProject.Setup(p => p.EnumerateItems("/"))
+                .Returns(new[]
+                {
+                    GetProjectItem("/", "/base-path/Test.cshtml", $"@page \"Home\" {Environment.NewLine}<h1>Hello world</h1>"),
+                    GetProjectItem("/", "/base-path/Index.cshtml", $"@page {Environment.NewLine}"),
+                    GetProjectItem("/", "/base-path/Admin/Index.cshtml", $"@page{Environment.NewLine}"),
+                    GetProjectItem("/", "/base-path/Admin/User.cshtml", $"@page{Environment.NewLine}"),
+                });
+            var options = GetRazorPagesOptions();
+
+            var provider = new PageActionDescriptorProvider(
+                razorProject.Object,
+                GetAccessor<MvcOptions>(),
+                options);
+            var context = new ActionDescriptorProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                result => Assert.Equal("base-path/Test/Home", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path/Index", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path/Admin/Index", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path/Admin", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path/Admin/User", result.AttributeRouteInfo.Template));
+        }
+
+        [Fact]
+        public void GetDescriptors_UsesBasePathOption_WhenGeneratingRouteTemplate()
+        {
+            // Arrange
+            var razorProject = new Mock<RazorProject>(MockBehavior.Strict);
+            razorProject.Setup(p => p.EnumerateItems("/base-path"))
+                .Returns(new[]
+                {
+                    GetProjectItem("/base-path", "/Test.cshtml", $"@page \"Home\" {Environment.NewLine}<h1>Hello world</h1>"),
+                    GetProjectItem("/base-path", "/Index.cshtml", $"@page {Environment.NewLine}"),
+                    GetProjectItem("/base-path", "/Admin/Index.cshtml", $"@page{Environment.NewLine}"),
+                    GetProjectItem("/base-path", "/Admin/User.cshtml", $"@page{Environment.NewLine}"),
+                });
+            var options = GetRazorPagesOptions();
+            options.Value.RootDirectory = "/base-path";
+            var provider = new PageActionDescriptorProvider(
+                razorProject.Object,
+                GetAccessor<MvcOptions>(),
+                options);
+            var context = new ActionDescriptorProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                result => Assert.Equal("Test/Home", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("Index", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("Admin/Index", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("Admin", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("Admin/User", result.AttributeRouteInfo.Template));
+
+        }
+
         [Theory]
         [InlineData("/Path1")]
         [InlineData("~/Path1")]
@@ -232,7 +301,6 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 });
         }
 
-
         [Fact]
         public void GetDescriptors_AddsGlobalFilters()
         {

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageActionDescriptorChangeProviderTest.cs

@@ -0,0 +1,54 @@
+// 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.Razor.Internal;
+using Microsoft.Extensions.FileProviders;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class PageActionDescriptorChangeProviderTest
+    {
+        [Fact]
+        public void GetChangeToken_WatchesAllCshtmlFilesUnderFileSystemRoot()
+        {
+            // Arrange
+            var options = new TestOptionsManager<RazorPagesOptions>();
+            var fileProvider = new Mock<IFileProvider>();
+            var fileProviderAccessor = new Mock<IRazorViewEngineFileProviderAccessor>();
+            fileProviderAccessor
+                .Setup(f => f.FileProvider)
+                .Returns(fileProvider.Object);
+            var changeProvider = new PageActionDescriptorChangeProvider(fileProviderAccessor.Object, options);
+
+            // Act
+            var changeToken = changeProvider.GetChangeToken();
+
+            // Assert
+            fileProvider.Verify(f => f.Watch("/**/*.cshtml"));
+        }
+
+        [Theory]
+        [InlineData("/pages-base-dir")]
+        [InlineData("/pages-base-dir/")]
+        public void GetChangeToken_WatchesAllCshtmlFilesUnderSpecifiedRootDirectory(string rootDirectory)
+        {
+            // Arrange
+            var options = new TestOptionsManager<RazorPagesOptions>();
+            options.Value.RootDirectory = rootDirectory;
+            var fileProvider = new Mock<IFileProvider>();
+            var fileProviderAccessor = new Mock<IRazorViewEngineFileProviderAccessor>();
+            fileProviderAccessor
+                .Setup(f => f.FileProvider)
+                .Returns(fileProvider.Object);
+            var changeProvider = new PageActionDescriptorChangeProvider(fileProviderAccessor.Object, options);
+
+            // Act
+            var changeToken = changeProvider.GetChangeToken();
+
+            // Assert
+            fileProvider.Verify(f => f.Watch("/pages-base-dir/**/*.cshtml"));
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.TestCommon/TestDirectoryContent.cs

@@ -0,0 +1,25 @@
+// 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.Collections;
+using System.Collections.Generic;
+using Microsoft.Extensions.FileProviders;
+
+namespace Microsoft.AspNetCore.Mvc.TestCommon
+{
+    public class TestDirectoryContent : IDirectoryContents
+    {
+        private readonly IEnumerable<IFileInfo> _files;
+
+        public TestDirectoryContent(IEnumerable<IFileInfo> files)
+        {
+            _files = files;
+        }
+
+        public bool Exists => true;
+
+        public IEnumerator<IFileInfo> GetEnumerator() => _files.GetEnumerator();
+
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+    }
+}

test/Microsoft.AspNetCore.Mvc.TestCommon/TestDirectoryFileInfo.cs

@@ -0,0 +1,30 @@
+// 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.Text;
+using Microsoft.Extensions.FileProviders;
+
+namespace Microsoft.AspNetCore.Mvc.Razor
+{
+    public class TestDirectoryFileInfo : IFileInfo
+    {
+        public bool IsDirectory => true;
+
+        public long Length { get; set; }
+
+        public string Name { get; set; }
+
+        public string PhysicalPath { get; set; }
+
+        public bool Exists => true;
+
+        public DateTimeOffset LastModified => throw new NotImplementedException();
+
+        public Stream CreateReadStream()
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.TestCommon/TestFileProvider.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using Microsoft.AspNetCore.Mvc.TestCommon;
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Primitives;
 
@@ -13,12 +14,20 @@ namespace Microsoft.AspNetCore.Mvc.Razor
     {
         private readonly Dictionary<string, IFileInfo> _lookup =
             new Dictionary<string, IFileInfo>(StringComparer.Ordinal);
+        private readonly Dictionary<string, IDirectoryContents> _directoryContentsLookup =
+            new Dictionary<string, IDirectoryContents>();
+
         private readonly Dictionary<string, TestFileChangeToken> _fileTriggers =
             new Dictionary<string, TestFileChangeToken>(StringComparer.Ordinal);
 
         public virtual IDirectoryContents GetDirectoryContents(string subpath)
         {
-            throw new NotSupportedException();
+            if (_directoryContentsLookup.TryGetValue(subpath, out var value))
+            {
+                return value;
+            }
+
+            return new NotFoundDirectoryContents();
         }
 
         public TestFileInfo AddFile(string path, string contents)
@@ -36,6 +45,13 @@ namespace Microsoft.AspNetCore.Mvc.Razor
             return fileInfo;
         }
 
+        public TestDirectoryContent AddDirectoryContent(string path, IEnumerable<IFileInfo> files)
+        {
+            var directoryContent = new TestDirectoryContent(files);
+            _directoryContentsLookup[path] = directoryContent;
+            return directoryContent;
+        }
+
         public void AddFile(string path, IFileInfo contents)
         {
             _lookup[path] = contents;

test/WebSites/RazorPagesWebSite/Pages/Admin/Index.cshtml

@@ -0,0 +1,2 @@
+@page
+Hello from @ViewContext.RouteData.Values["page"]

test/WebSites/RazorPagesWebSite/Pages/Admin/RouteTemplate.cshtml

@@ -0,0 +1,2 @@
+@page "{id}/MyRouteSuffix/{value:int?}"
+Hello from @ViewContext.RouteData.Values["page"] @ViewContext.RouteData.Values["id"] @ViewContext.RouteData.Values["value"]

test/WebSites/RazorPagesWebSite/Pages/Conventions/Auth.cshtml

@@ -0,0 +1 @@
+@page

test/WebSites/RazorPagesWebSite/Pages/Conventions/AuthFolder/Index.cshtml

@@ -0,0 +1 @@
+@page

test/WebSites/RazorPagesWebSite/Pages/Index.cshtml

@@ -0,0 +1,2 @@
+@page
+Hello from @ViewContext.RouteData.Values["page"]

test/WebSites/RazorPagesWebSite/RazorPagesWebSite.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
   <Import Project="..\..\..\build\common.props" />
 
   <PropertyGroup>

test/WebSites/RazorPagesWebSite/StartupWithBasePath.cs

@@ -0,0 +1,40 @@
+// 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.Builder;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace RazorPagesWebSite
+{
+    public class StartupWithBasePath
+    {
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services
+                .AddMvc()
+                .AddCookieTempDataProvider()
+                .AddRazorPagesOptions(options =>
+                {
+                    options.RootDirectory = "/Pages";
+                    options.AuthorizePage("/Conventions/Auth", string.Empty);
+                    options.AuthorizeFolder("/Conventions/AuthFolder", string.Empty);
+                });
+        }
+
+        public void Configure(IApplicationBuilder app)
+        {
+            app.UseCultureReplacer();
+
+            app.UseCookieAuthentication(new CookieAuthenticationOptions
+            {
+                LoginPath = "/Login",
+                AutomaticAuthenticate = true,
+                AutomaticChallenge = true
+            });
+
+            app.UseStaticFiles();
+
+            app.UseMvc();
+        }
+    }
+}