Normalize paths returned by view location expanders

Fixes #6448

src/Microsoft.AspNetCore.Mvc.Razor/Compilation/CompiledViewDescriptor.cs

@@ -8,6 +8,9 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
 {
     public class CompiledViewDescriptor
     {
+        /// <summary>
+        /// The normalized application relative path of the view.
+        /// </summary>
         public string RelativePath { get; set; }
 
         /// <summary>

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

@@ -57,11 +57,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
                 var pageFactory = Expression
                     .Lambda<Func<IRazorPage>>(objectInitializeExpression)
                     .Compile();
-                return new RazorPageFactoryResult(pageFactory, viewDescriptor.ExpirationTokens, viewDescriptor.IsPrecompiled);
+                return new RazorPageFactoryResult(viewDescriptor, pageFactory);
             }
             else
             {
-                return new RazorPageFactoryResult(viewDescriptor.ExpirationTokens);
+                return new RazorPageFactoryResult(viewDescriptor, razorPageFactory: null);
             }
         }
     }

src/Microsoft.AspNetCore.Mvc.Razor/RazorPageFactoryResult.cs

@@ -2,8 +2,7 @@
 // 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 Microsoft.AspNetCore.Mvc.Razor.Compilation;
-using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Mvc.Razor
 {
@@ -12,61 +11,18 @@ namespace Microsoft.AspNetCore.Mvc.Razor
     /// </summary>
     public struct RazorPageFactoryResult
     {
-        /// <summary>
-        /// Initializes a new instance of <see cref="RazorPageFactoryResult"/> with the
-        /// specified <paramref name="expirationTokens"/>.
-        /// </summary>
-        /// <param name="expirationTokens">One or more <see cref="IChangeToken"/> instances.</param>
-        public RazorPageFactoryResult(IList<IChangeToken> expirationTokens)
-        {
-            if (expirationTokens == null)
-            {
-                throw new ArgumentNullException(nameof(expirationTokens));
-            }
-
-            ExpirationTokens = expirationTokens;
-            RazorPageFactory = null;
-            IsPrecompiled = false;
-        }
-
         /// <summary>
         /// Initializes a new instance of <see cref="RazorPageFactoryResult"/> with the
         /// specified <see cref="IRazorPage"/> factory.
         /// </summary>
         /// <param name="razorPageFactory">The <see cref="IRazorPage"/> factory.</param>
-        /// <param name="expirationTokens">One or more <see cref="IChangeToken"/> instances.</param>
+        /// <param name="viewDescriptor">The <see cref="CompiledViewDescriptor"/>.</param>
         public RazorPageFactoryResult(
-            Func<IRazorPage> razorPageFactory,
+            CompiledViewDescriptor viewDescriptor,
-            IList<IChangeToken> expirationTokens)
+            Func<IRazorPage> razorPageFactory)
-            : this(razorPageFactory, expirationTokens, isPrecompiled: false)
         {
-        }
+            ViewDescriptor = viewDescriptor ?? throw new ArgumentNullException(nameof(viewDescriptor));
-
-        /// <summary>
-        /// Initializes a new instance of <see cref="RazorPageFactoryResult"/> with the
-        /// specified <see cref="IRazorPage"/> factory.
-        /// </summary>
-        /// <param name="razorPageFactory">The <see cref="IRazorPage"/> factory.</param>
-        /// <param name="expirationTokens">One or more <see cref="IChangeToken"/> instances.</param>
-        /// <param name="isPrecompiled"><c>true</c> if the view is precompiled, <c>false</c> otherwise.</param>
-        public RazorPageFactoryResult(
-            Func<IRazorPage> razorPageFactory,
-            IList<IChangeToken> expirationTokens,
-            bool isPrecompiled)
-        {
-            if (razorPageFactory == null)
-            {
-                throw new ArgumentNullException(nameof(razorPageFactory));
-            }
-
-            if (expirationTokens == null)
-            {
-                throw new ArgumentNullException(nameof(expirationTokens));
-            }
-
             RazorPageFactory = razorPageFactory;
-            ExpirationTokens = expirationTokens;
-            IsPrecompiled = isPrecompiled;
         }
 
         /// <summary>
@@ -76,19 +32,13 @@ namespace Microsoft.AspNetCore.Mvc.Razor
         public Func<IRazorPage> RazorPageFactory { get; }
 
         /// <summary>
-        /// One or more <see cref="IChangeToken"/>s associated with this instance of
+        /// Gets the <see cref="CompiledViewDescriptor"/>.
-        /// <see cref="RazorPageFactoryResult"/>.
         /// </summary>
-        public IList<IChangeToken> ExpirationTokens { get; }
+        public CompiledViewDescriptor ViewDescriptor { get; }
 
         /// <summary>
         /// Gets a value that determines if the page was successfully located.
         /// </summary>
         public bool Success => RazorPageFactory != null;
-
-        /// <summary>
-        /// Gets a value that determines if the view is precompiled.
-        /// </summary>
-        public bool IsPrecompiled { get; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Razor/RazorViewEngine.cs

@@ -396,11 +396,12 @@ namespace Microsoft.AspNetCore.Mvc.Razor
             bool isMainPage)
         {
             var factoryResult = _pageFactory.CreateFactory(relativePath);
-            if (factoryResult.ExpirationTokens != null)
+            var viewDescriptor = factoryResult.ViewDescriptor;
+            if (viewDescriptor?.ExpirationTokens != null)
             {
-                for (var i = 0; i < factoryResult.ExpirationTokens.Count; i++)
+                for (var i = 0; i < viewDescriptor.ExpirationTokens.Count; i++)
                 {
-                    expirationTokens.Add(factoryResult.ExpirationTokens[i]);
+                    expirationTokens.Add(viewDescriptor.ExpirationTokens[i]);
                 }
             }
 
@@ -408,9 +409,9 @@ namespace Microsoft.AspNetCore.Mvc.Razor
             {
                 // Only need to lookup _ViewStarts for the main page.
                 var viewStartPages = isMainPage ?
-                    GetViewStartPages(relativePath, expirationTokens) :
+                    GetViewStartPages(viewDescriptor.RelativePath, expirationTokens) :
                     Array.Empty<ViewLocationCacheItem>();
-                if (factoryResult.IsPrecompiled)
+                if (viewDescriptor.IsPrecompiled)
                 {
                     _logger.PrecompiledViewFound(relativePath);
                 }
@@ -427,17 +428,17 @@ namespace Microsoft.AspNetCore.Mvc.Razor
             string path,
             HashSet<IChangeToken> expirationTokens)
         {
-            var applicationRelativePath = MakePathApplicationRelative(path);
             var viewStartPages = new List<ViewLocationCacheItem>();
 
-            foreach (var viewStartProjectItem in _razorProject.FindHierarchicalItems(applicationRelativePath, ViewStartFileName))
+            foreach (var viewStartProjectItem in _razorProject.FindHierarchicalItems(path, ViewStartFileName))
             {
                 var result = _pageFactory.CreateFactory(viewStartProjectItem.Path);
-                if (result.ExpirationTokens != null)
+                var viewDescriptor = result.ViewDescriptor;
+                if (viewDescriptor?.ExpirationTokens != null)
                 {
-                    for (var i = 0; i < result.ExpirationTokens.Count; i++)
+                    for (var i = 0; i < viewDescriptor.ExpirationTokens.Count; i++)
                     {
-                        expirationTokens.Add(result.ExpirationTokens[i]);
+                        expirationTokens.Add(viewDescriptor.ExpirationTokens[i]);
                     }
                 }
 
@@ -479,22 +480,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor
             return name[0] == '~' || name[0] == '/';
         }
 
-        private string MakePathApplicationRelative(string path)
-        {
-            Debug.Assert(!string.IsNullOrEmpty(path));
-            if (path[0] == '~')
-            {
-                path = path.Substring(1);
-            }
-
-            if (path[0] != '/')
-            {
-                path = '/' + path;
-            }
-
-            return path;
-        }
-
         private static bool IsRelativePath(string name)
         {
             Debug.Assert(!string.IsNullOrEmpty(name));

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

@@ -476,5 +476,21 @@ Partial that does not specify Layout
                 ignoreLineEndingDifferences: true);
 #endif
         }
+
+        [Fact]
+        public async Task ViewEngine_NormalizesPathsReturnedByViewLocationExpanders()
+        {
+            // Arrange
+            var expected = 
+@"Layout
+Page
+Partial";
+
+            // Act
+            var responseContent = await Client.GetStringAsync("/BackSlash");
+
+            // Assert
+            Assert.Equal(expected, responseContent.Trim());
+        }
     }
 }

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

@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
     public class DefaultRazorPageFactoryProviderTest
     {
         [Fact]
-        public void CreateFactory_ReturnsExpirationTokensFromCompilerCache_ForUnsuccessfulResults()
+        public void CreateFactory_ReturnsViewDescriptor_ForUnsuccessfulResults()
         {
             // Arrange
             var path = "/file-does-not-exist";
@@ -39,11 +39,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Internal
 
             // Assert
             Assert.False(result.Success);
-            Assert.Equal(expirationTokens, result.ExpirationTokens);
+            Assert.Same(descriptor, result.ViewDescriptor);
         }
 
         [Fact]
-        public void CreateFactory_ReturnsExpirationTokensFromCompilerCache_ForSuccessfulResults()
+        public void CreateFactory_ReturnsViewDescriptor_ForSuccessfulResults()
         {
             // Arrange
             var relativePath = "/file-exists";

test/Microsoft.AspNetCore.Mvc.Razor.Test/RazorViewEngineTest.cs

@@ -8,6 +8,7 @@ using System.Threading;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
 using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Mvc.ViewEngines;
@@ -169,15 +170,15 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/bar/test-view.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page));
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => viewStart2, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => viewStart2));
 
             pageFactory
                 .Setup(p => p.CreateFactory("/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => viewStart1, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => viewStart1));
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
             var context = GetActionContext(_controllerTestContext);
@@ -205,11 +206,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/bar/test-view.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page));
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => viewStart, new[] { changeToken }));
+                .Returns(GetPageFactoryResult(() => viewStart, new[] { changeToken }));
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
             var context = GetActionContext(_controllerTestContext);
@@ -334,15 +335,15 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/bar/test-view.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page));
 
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => viewStart2, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => viewStart2));
 
             pageFactory
                 .Setup(p => p.CreateFactory("/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => viewStart1, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => viewStart1));
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
             var context = GetActionContext(_controllerTestContext);
@@ -370,7 +371,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory("fake-path1/bar/test-view.rzr"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -398,7 +399,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedViewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -427,7 +428,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedViewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -453,7 +454,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedViewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -481,7 +482,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(viewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -509,7 +510,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedViewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -537,7 +538,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedViewName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -565,10 +566,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var nonAreaPage = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory("/Areas/Admin/Views/Home/Index.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => areaPage, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => areaPage));
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/Home/Index.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => nonAreaPage, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => nonAreaPage));
 
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -629,10 +630,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var areaPage2 = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory("/Areas/Marketing/Views/Home/Index.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => areaPage1, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => areaPage1));
             pageFactory
                 .Setup(p => p.CreateFactory("/Areas/Sales/Views/Home/Index.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => areaPage2, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => areaPage2));
 
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -693,7 +694,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory("test-string/bar.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => Mock.Of<IRazorPage>(), new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => Mock.Of<IRazorPage>()))
                 .Verifiable();
 
             var expander1Result = new[] { "some-seed" };
@@ -746,6 +747,37 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             expander2.Verify();
         }
 
+        [Fact]
+        public void FindView_NoramlizesPaths_ReturnedByViewLocationExpanders()
+        {
+            // Arrange
+            var pageFactory = new Mock<IRazorPageFactoryProvider>();
+            pageFactory
+                .Setup(p => p.CreateFactory(@"Views\Home\Index.cshtml"))
+                .Returns(GetPageFactoryResult(() => Mock.Of<IRazorPage>()))
+                .Verifiable();
+
+            var expander = new Mock<IViewLocationExpander>();
+            expander
+                .Setup(e => e.ExpandViewLocations(
+                    It.IsAny<ViewLocationExpanderContext>(),
+                    It.IsAny<IEnumerable<string>>()))
+                .Returns(new[] { @"Views\Home\Index.cshtml" });
+
+            var viewEngine = CreateViewEngine(
+                pageFactory.Object,
+                new[] { expander.Object });
+            var context = GetActionContext(new Dictionary<string, object>());
+
+            // Act
+            var result = viewEngine.FindView(context, "test-view", isMainPage: true);
+
+            // Assert
+            Assert.True(result.Success);
+            Assert.IsAssignableFrom<IView>(result.View);
+            pageFactory.Verify();
+        }
+
         [Fact]
         public void FindView_CachesValuesIfViewWasFound()
         {
@@ -754,11 +786,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/bar/baz.cshtml"))
-                .Returns(new RazorPageFactoryResult(new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(factory: null))
                 .Verifiable();
             pageFactory
                .Setup(p => p.CreateFactory("/Views/Shared/baz.cshtml"))
-               .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+               .Returns(GetPageFactoryResult(() => page))
                .Verifiable();
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
@@ -795,7 +827,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                .Setup(p => p.CreateFactory("/Views/Shared/baz.cshtml"))
-               .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+               .Returns(GetPageFactoryResult(() => page))
                .Verifiable();
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
@@ -838,16 +870,16 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             pageFactory
                 .InSequence(sequence)
                 .Setup(p => p.CreateFactory("/Views/bar/baz.cshtml"))
-                .Returns(new RazorPageFactoryResult(new[] { changeToken }));
+                .Returns(GetPageFactoryResult(factory: null, changeTokens: new[] { changeToken }));
             pageFactory
                .InSequence(sequence)
                .Setup(p => p.CreateFactory("/Views/Shared/baz.cshtml"))
-               .Returns(new RazorPageFactoryResult(() => page1, new IChangeToken[0]))
+               .Returns(GetPageFactoryResult(() => page1))
                .Verifiable();
             pageFactory
                 .InSequence(sequence)
                 .Setup(p => p.CreateFactory("/Views/bar/baz.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page2, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page2));
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
             var context = GetActionContext(_controllerTestContext);
@@ -886,20 +918,20 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             pageFactory
                 .InSequence(sequence)
                 .Setup(p => p.CreateFactory("/Views/bar/baz.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page1, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page1));
             pageFactory
                 .InSequence(sequence)
                .Setup(p => p.CreateFactory("/Views/_ViewStart.cshtml"))
-               .Returns(new RazorPageFactoryResult(new[] { changeToken }))
+               .Returns(GetPageFactoryResult(factory: null, changeTokens: new[] { changeToken }))
                .Verifiable();
             pageFactory
                 .InSequence(sequence)
                 .Setup(p => p.CreateFactory("/Views/bar/baz.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page2, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page2));
             pageFactory
                 .InSequence(sequence)
                .Setup(p => p.CreateFactory("/Views/_ViewStart.cshtml"))
-               .Returns(new RazorPageFactoryResult(() => viewStart, new IChangeToken[0]));
+               .Returns(GetPageFactoryResult(() => viewStart));
 
             var fileProvider = new TestFileProvider();
             var razorProject = new FileProviderRazorProject(fileProvider);
@@ -993,7 +1025,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory("viewlocation3"))
-                .Returns(new RazorPageFactoryResult(new[] { changeToken }));
+                .Returns(GetPageFactoryResult(factory: null, changeTokens: new[] { changeToken }));
             var expander = new Mock<IViewLocationExpander>();
             var expandedLocations = new[]
             {
@@ -1031,7 +1063,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             // Act - 2
             pageFactory
                 .Setup(p => p.CreateFactory("viewlocation3"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => page));
             cancellationTokenSource.Cancel();
             result = viewEngine.FindView(context, "MyView", isMainPage: true);
 
@@ -1131,7 +1163,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory("expanded-path/bar-layout"))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
 
             var expander = new Mock<IViewLocationExpander>();
@@ -1210,7 +1242,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory("/Views/Foo/details.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => page.Object, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page.Object))
                 .Verifiable();
 
             var viewEngine = CreateViewEngine(pageFactory.Object);
@@ -1339,10 +1371,12 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var loggerFactory = new TestLoggerFactory(sink, enabled: true);
 
             var relativePath = "/Views/Foo/details.cshtml";
+            var factoryResult = GetPageFactoryResult(() => Mock.Of<IRazorPage>());
+            factoryResult.ViewDescriptor.IsPrecompiled = true;
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory(relativePath))
-                .Returns(new RazorPageFactoryResult(() => Mock.Of<IRazorPage>(), new IChangeToken[0], isPrecompiled: true))
+                .Returns(factoryResult)
                 .Verifiable();
 
             var viewEngine = new RazorViewEngine(
@@ -1375,7 +1409,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(pageName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -1403,7 +1437,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedPageName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -1431,7 +1465,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var page = Mock.Of<IRazorPage>();
             pageFactory
                 .Setup(p => p.CreateFactory(expectedPageName))
-                .Returns(new RazorPageFactoryResult(() => page, new IChangeToken[0]))
+                .Returns(GetPageFactoryResult(() => page))
                 .Verifiable();
             var viewEngine = new TestableRazorViewEngine(
                 pageFactory.Object,
@@ -1761,11 +1795,25 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var pageFactory = new Mock<IRazorPageFactoryProvider>(MockBehavior.Strict);
             pageFactory
                 .Setup(f => f.CreateFactory(It.IsAny<string>()))
-                .Returns(new RazorPageFactoryResult(() => Mock.Of<IRazorPage>(), new IChangeToken[0]));
+                .Returns(GetPageFactoryResult(() => Mock.Of<IRazorPage>()));
 
             return CreateViewEngine(pageFactory.Object);
         }
 
+        private static RazorPageFactoryResult GetPageFactoryResult(
+            Func<IRazorPage> factory,
+            IList<IChangeToken> changeTokens = null,
+            string path = "/Views/Home/Index.cshtml")
+        {
+            var descriptor = new CompiledViewDescriptor
+            {
+                ExpirationTokens = changeTokens ?? Array.Empty<IChangeToken>(),
+                RelativePath = path,
+            };
+
+            return new RazorPageFactoryResult(descriptor, factory);
+        }
+
         private TestableRazorViewEngine CreateViewEngine(
             IRazorPageFactoryProvider pageFactory = null,
             IEnumerable<IViewLocationExpander> expanders = null,

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

@@ -10,6 +10,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
@@ -255,10 +256,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor
                 v.Write("layout-content" + Environment.NewLine);
                 v.RenderBodyPublic();
             });
+            var pageFactoryResult = new RazorPageFactoryResult(new CompiledViewDescriptor(), () => layout);
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(p => p.CreateFactory(LayoutPath))
-                .Returns(new RazorPageFactoryResult(() => layout, new IChangeToken[0]));
+                .Returns(pageFactoryResult);
 
             var viewEngine = new Mock<IRazorViewEngine>(MockBehavior.Strict);
             viewEngine

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

@@ -13,6 +13,7 @@ using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 using Microsoft.AspNetCore.Mvc.Razor;
+using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
 using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Rendering;
@@ -181,10 +182,10 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             razorPageFactoryProvider
                 .Setup(f => f.CreateFactory("/Home/Path1/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(factory1, new IChangeToken[0]));
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), factory1));
             razorPageFactoryProvider
                 .Setup(f => f.CreateFactory("/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(factory2, new[] { Mock.Of<IChangeToken>() }));
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), factory2));
 
             var fileProvider = new TestFileProvider();
             fileProvider.AddFile("/Home/Path1/_ViewStart.cshtml", "content1");
@@ -215,7 +216,6 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             Assert.Equal(new[] { factory2, factory1 }, entry.ViewStartFactories);
         }
 
-
         [Fact]
         public void OnProvidersExecuting_CachesEntries()
         {
@@ -347,19 +347,19 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             var mock = new Mock<IRazorPageFactoryProvider>(MockBehavior.Strict);
             mock
                 .Setup(p => p.CreateFactory("/Pages/Level1/Level2/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new List<IChangeToken>()))
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null))
                 .Verifiable();
             mock
                 .Setup(p => p.CreateFactory("/Pages/Level1/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new List<IChangeToken>()))
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null))
                 .Verifiable();
             mock
                 .Setup(p => p.CreateFactory("/Pages/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new List<IChangeToken>()))
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null))
                 .Verifiable();
             mock
                 .Setup(p => p.CreateFactory("/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new List<IChangeToken>()))
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null))
                 .Verifiable();
 
             var razorPageFactoryProvider = mock.Object;
@@ -398,13 +398,13 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             var pageFactory = new Mock<IRazorPageFactoryProvider>();
             pageFactory
                 .Setup(f => f.CreateFactory("/Views/Deeper/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new IChangeToken[0]));
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null));
             pageFactory
                 .Setup(f => f.CreateFactory("/Views/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(new IChangeToken[0]));
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), razorPageFactory: null));
             pageFactory
                 .Setup(f => f.CreateFactory("/_ViewStart.cshtml"))
-                .Returns(new RazorPageFactoryResult(() => null, new IChangeToken[0]));
+                .Returns(new RazorPageFactoryResult(new CompiledViewDescriptor(), () => null));
 
             // No files
             var fileProvider = new TestFileProvider();

test/WebSites/RazorWebSite/Controllers/BackSlashController.cs

@@ -0,0 +1,12 @@
+// 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;
+
+namespace RazorWebSite.Controllers
+{
+    public class BackSlashController : Controller
+    {
+        public IActionResult Index() => View(@"Views\BackSlash\BackSlashView.cshtml");
+    }
+}

test/WebSites/RazorWebSite/RazorWebSite.csproj

@@ -19,5 +19,6 @@
     <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="$(AspNetCoreVersion)" />
     <PackageReference Include="Microsoft.Extensions.FileProviders.Embedded" Version="$(AspNetCoreVersion)" />
+    <PackageReference Include="Microsoft.AspNetCore.Diagnostics" Version="$(AspNetCoreVersion)" />
   </ItemGroup>
 </Project>

test/WebSites/RazorWebSite/Services/BackSlashExpander.cs

@@ -0,0 +1,27 @@
+// 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.Generic;
+using Microsoft.AspNetCore.Mvc.Razor;
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace RazorWebSite
+{
+    public class ForwardSlashExpander : IViewLocationExpander
+    {
+        public void PopulateValues(ViewLocationExpanderContext context)
+        {
+        }
+
+        public virtual IEnumerable<string> ExpandViewLocations(ViewLocationExpanderContext context, IEnumerable<string> viewLocations)
+        {
+            if (context.ActionContext is ViewContext viewContext && (string)viewContext.ViewData["back-slash"] == "true")
+            {
+                return new[] { $@"Views\BackSlash\{context.ViewName}.cshtml" };
+                
+            }
+
+            return viewLocations;
+        }
+    }
+}

test/WebSites/RazorWebSite/Startup.cs

@@ -33,6 +33,7 @@ namespace RazorWebSite
                         $"{nameof(RazorWebSite)}.EmbeddedViews"));
                     options.FileProviders.Add(updateableFileProvider);
                     options.ViewLocationExpanders.Add(new NonMainPageViewLocationExpander());
+                    options.ViewLocationExpanders.Add(new ForwardSlashExpander());
                 })
                 .AddViewOptions(options =>
                 {
@@ -51,6 +52,7 @@ namespace RazorWebSite
 
         public void Configure(IApplicationBuilder app)
         {
+            app.UseDeveloperExceptionPage();
             app.UseRequestLocalization(new RequestLocalizationOptions
             {
                 DefaultRequestCulture = new RequestCulture("en-GB", "en-US"),

test/WebSites/RazorWebSite/Views/BackSlash/BackSlashView.cshtml

@@ -0,0 +1,6 @@
+@{
+  ViewData["back-slash"] = "true";
+  Layout = "_Layout";
+}
+Page
+@Html.Partial("_BackSlashPartial")

test/WebSites/RazorWebSite/Views/BackSlash/_BackSlashPartial.cshtml

@@ -0,0 +1 @@
+Partial

test/WebSites/RazorWebSite/Views/BackSlash/_Layout.cshtml

@@ -0,0 +1,2 @@
+Layout
+@RenderBody()