Use checksum for classname if filepath is null

src/Microsoft.AspNetCore.Mvc.Razor.Extensions.Version1_X/MvcViewDocumentClassifierPass.cs

@@ -1,6 +1,8 @@
 // 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.Text;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
@@ -25,7 +27,18 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions.Version1_X
             @namespace.Content = "AspNetCore";
 
             var filePath = codeDocument.Source.RelativePath ?? codeDocument.Source.FilePath;
-            @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            if (string.IsNullOrEmpty(filePath))
+            {
+                // It's possible for a Razor document to not have a file path.
+                // Eg. When we try to generate code for an in memory document like default imports.
+                var checksum = BytesToString(codeDocument.Source.GetChecksum());
+                @class.ClassName = $"AspNetCore_{checksum}";
+            }
+            else
+            {
+                @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            }
+
             @class.BaseType = "global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<TModel>";
             @class.Modifiers.Clear();
             @class.Modifiers.Add("public");
@@ -37,5 +50,22 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions.Version1_X
             method.Modifiers.Add("override");
             method.ReturnType = $"global::{typeof(System.Threading.Tasks.Task).FullName}";
         }
+
+        private static string BytesToString(byte[] bytes)
+        {
+            if (bytes == null)
+            {
+                throw new ArgumentNullException(nameof(bytes));
+            }
+
+            var result = new StringBuilder(bytes.Length);
+            for (var i = 0; i < bytes.Length; i++)
+            {
+                // The x2 format means lowercase hex, where each byte is a 2-character string.
+                result.Append(bytes[i].ToString("x2"));
+            }
+
+            return result.ToString();
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.Razor.Extensions/MvcViewDocumentClassifierPass.cs

@@ -1,6 +1,8 @@
 // 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.Text;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
@@ -25,7 +27,18 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             @namespace.Content = "AspNetCore";
 
             var filePath = codeDocument.Source.RelativePath ?? codeDocument.Source.FilePath;
-            @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            if (string.IsNullOrEmpty(filePath))
+            {
+                // It's possible for a Razor document to not have a file path.
+                // Eg. When we try to generate code for an in memory document like default imports.
+                var checksum = BytesToString(codeDocument.Source.GetChecksum());
+                @class.ClassName = $"AspNetCore_{checksum}";
+            }
+            else
+            {
+                @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            }
+
             @class.BaseType = "global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<TModel>";
             @class.Modifiers.Clear();
             @class.Modifiers.Add("public");
@@ -37,5 +50,22 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             method.Modifiers.Add("override");
             method.ReturnType = $"global::{typeof(System.Threading.Tasks.Task).FullName}";
         }
+
+        private static string BytesToString(byte[] bytes)
+        {
+            if (bytes == null)
+            {
+                throw new ArgumentNullException(nameof(bytes));
+            }
+
+            var result = new StringBuilder(bytes.Length);
+            for (var i = 0; i < bytes.Length; i++)
+            {
+                // The x2 format means lowercase hex, where each byte is a 2-character string.
+                result.Append(bytes[i].ToString("x2"));
+            }
+
+            return result.ToString();
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.Razor.Extensions/RazorPageDocumentClassifierPass.cs

@@ -1,7 +1,9 @@
 // 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.Diagnostics;
+using System.Text;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
@@ -52,7 +54,17 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             @class.BaseType = "global::Microsoft.AspNetCore.Mvc.RazorPages.Page";
 
             var filePath = codeDocument.Source.RelativePath ?? codeDocument.Source.FilePath;
-            @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            if (string.IsNullOrEmpty(filePath))
+            {
+                // It's possible for a Razor document to not have a file path.
+                // Eg. When we try to generate code for an in memory document like default imports.
+                var checksum = BytesToString(codeDocument.Source.GetChecksum());
+                @class.ClassName = $"AspNetCore_{checksum}";
+            }
+            else
+            {
+                @class.ClassName = CSharpIdentifier.GetClassNameFromPath(filePath);
+            }
 
             @class.Modifiers.Clear();
             @class.Modifiers.Add("public");
@@ -131,5 +143,22 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                 options.ParseLeadingDirectives = true;
             }
         }
+
+        private static string BytesToString(byte[] bytes)
+        {
+            if (bytes == null)
+            {
+                throw new ArgumentNullException(nameof(bytes));
+            }
+
+            var result = new StringBuilder(bytes.Length);
+            for (var i = 0; i < bytes.Length; i++)
+            {
+                // The x2 format means lowercase hex, where each byte is a 2-character string.
+                result.Append(bytes[i].ToString("x2"));
+            }
+
+            return result.ToString();
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/MvcViewDocumentClassifierPassTest.cs

@@ -97,6 +97,31 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             Assert.Equal("Test", visitor.Class.ClassName);
         }
 
+        [Fact]
+        public void MvcViewDocumentClassifierPass_NullFilePath_SetsClass()
+        {
+            // Arrange
+            var properties = new RazorSourceDocumentProperties(filePath: null, relativePath: null);
+            var codeDocument = RazorCodeDocument.Create(RazorSourceDocument.Create("some-content", properties));
+
+            var projectEngine = CreateProjectEngine();
+            var irDocument = CreateIRDocument(projectEngine, codeDocument);
+            var pass = new MvcViewDocumentClassifierPass
+            {
+                Engine = projectEngine.Engine
+            };
+
+            // Act
+            pass.Execute(codeDocument, irDocument);
+            var visitor = new Visitor();
+            visitor.Visit(irDocument);
+
+            // Assert
+            Assert.Equal("global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<TModel>", visitor.Class.BaseType);
+            Assert.Equal(new[] { "public" }, visitor.Class.Modifiers);
+            Assert.Equal("AspNetCore_d9f877a857a7e9928eac04d09a59f25967624155", visitor.Class.ClassName);
+        }
+
         [Theory]
         [InlineData("/Views/Home/Index.cshtml", "_Views_Home_Index")]
         [InlineData("/Areas/MyArea/Views/Home/About.cshtml", "_Areas_MyArea_Views_Home_About")]

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/RazorPageDocumentClassifierPassTest.cs

@@ -212,6 +212,31 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             Assert.Equal("Test", visitor.Class.ClassName);
         }
 
+        [Fact]
+        public void RazorPageDocumentClassifierPass_NullFilePath_SetsClass()
+        {
+            // Arrange
+            var properties = new RazorSourceDocumentProperties(filePath: null, relativePath: null);
+            var codeDocument = RazorCodeDocument.Create(RazorSourceDocument.Create("@page", properties));
+
+            var engine = CreateEngine();
+            var irDocument = CreateIRDocument(engine, codeDocument);
+            var pass = new RazorPageDocumentClassifierPass
+            {
+                Engine = engine
+            };
+
+            // Act
+            pass.Execute(codeDocument, irDocument);
+            var visitor = new Visitor();
+            visitor.Visit(irDocument);
+
+            // Assert
+            Assert.Equal("global::Microsoft.AspNetCore.Mvc.RazorPages.Page", visitor.Class.BaseType);
+            Assert.Equal(new[] { "public" }, visitor.Class.Modifiers);
+            Assert.Equal("AspNetCore_74fbaab062bb228ed1ab09c5ff8d6ed2417320e2", visitor.Class.ClassName);
+        }
+
         [Theory]
         [InlineData("/Views/Home/Index.cshtml", "_Views_Home_Index")]
         [InlineData("/Areas/MyArea/Views/Home/About.cshtml", "_Areas_MyArea_Views_Home_About")]

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Version1_X.Test/MvcViewDocumentClassifierPassTest.cs

@@ -97,6 +97,31 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions.Version1_X
             Assert.Equal("Test", visitor.Class.ClassName);
         }
 
+        [Fact]
+        public void MvcViewDocumentClassifierPass_NullFilePath_SetsClass()
+        {
+            // Arrange
+            var properties = new RazorSourceDocumentProperties(filePath: null, relativePath: null);
+            var codeDocument = RazorCodeDocument.Create(RazorSourceDocument.Create("some-content", properties));
+
+            var projectEngine = CreateProjectEngine();
+            var irDocument = CreateIRDocument(projectEngine, codeDocument);
+            var pass = new MvcViewDocumentClassifierPass
+            {
+                Engine = projectEngine.Engine
+            };
+
+            // Act
+            pass.Execute(codeDocument, irDocument);
+            var visitor = new Visitor();
+            visitor.Visit(irDocument);
+
+            // Assert
+            Assert.Equal("global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<TModel>", visitor.Class.BaseType);
+            Assert.Equal(new[] { "public" }, visitor.Class.Modifiers);
+            Assert.Equal("AspNetCore_d9f877a857a7e9928eac04d09a59f25967624155", visitor.Class.ClassName);
+        }
+
         [Theory]
         [InlineData("/Views/Home/Index.cshtml", "_Views_Home_Index")]
         [InlineData("/Areas/MyArea/Views/Home/About.cshtml", "_Areas_MyArea_Views_Home_About")]