Handle unreadable import items in design time

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorProjectEngine.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 
 namespace Microsoft.AspNetCore.Razor.Language
@@ -65,7 +66,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             var importFeature = GetRequiredFeature<IImportProjectFeature>();
             var importItems = importFeature.GetImports(projectItem);
-            var importSourceDocuments = importItems.Select(ConvertToSourceDocument);
+            var importSourceDocuments = importItems.Select(i => ConvertToSourceDocument(i));
 
             var parserOptions = GetRequiredFeature<IRazorParserOptionsFactoryProjectFeature>().Create(ConfigureParserOptions);
             var codeGenerationOptions = GetRequiredFeature<IRazorCodeGenerationOptionsFactoryProjectFeature>().Create(ConfigureCodeGenerationOptions);
@@ -84,12 +85,11 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             var importFeature = GetRequiredFeature<IImportProjectFeature>();
             var importItems = importFeature.GetImports(projectItem);
-            var importSourceDocuments = importItems.Select(ConvertToSourceDocument);
+            var importSourceDocuments = importItems.Select(i => ConvertToSourceDocument(i, suppressExceptions: true));
 
             var parserOptions = GetRequiredFeature<IRazorParserOptionsFactoryProjectFeature>().Create(ConfigureDesignTimeParserOptions);
             var codeGenerationOptions = GetRequiredFeature<IRazorCodeGenerationOptionsFactoryProjectFeature>().Create(ConfigureDesignTimeCodeGenerationOptions);
 
-
             return RazorCodeDocument.Create(sourceDocument, importSourceDocuments, parserOptions, codeGenerationOptions);
         }
 
@@ -138,12 +138,20 @@ namespace Microsoft.AspNetCore.Razor.Language
         }
 
         // Internal for testing
-        internal static RazorSourceDocument ConvertToSourceDocument(RazorProjectItem importItem)
+        internal static RazorSourceDocument ConvertToSourceDocument(RazorProjectItem importItem, bool suppressExceptions = false)
         {
             if (importItem.Exists)
             {
-                // Normal import, has file paths, content etc.
+                try
-                return RazorSourceDocument.ReadFrom(importItem);
+                {
+                    // Normal import, has file paths, content etc.
+                    return RazorSourceDocument.ReadFrom(importItem);
+                }
+                catch (IOException) when (suppressExceptions)
+                {
+                    // Something happened when trying to read the item from disk.
+                    // Catch the exception so we don't crash the editor.
+                }
             }
 
             // Marker import, doesn't exist, used as an identifier for "there could be something here".

test/Microsoft.AspNetCore.Razor.Language.Test/DefaultRazorProjectEngineTest.cs

@@ -1,6 +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 System.IO;
 using Moq;
 using Xunit;
 
@@ -33,5 +34,38 @@ namespace Microsoft.AspNetCore.Razor.Language
             // Assert
             Assert.NotNull(sourceDocument);
         }
+
+        [Fact]
+        public void ConvertToSourceDocument_UnreadableItem_Throws()
+        {
+            // Arrange
+            var projectItem = new Mock<RazorProjectItem>(MockBehavior.Strict);
+            projectItem.SetupGet(p => p.Exists).Returns(true);
+            projectItem.SetupGet(p => p.PhysicalPath).Returns("path/to/file.cshtml");
+            projectItem.Setup(p => p.Read()).Throws(new IOException("Couldn't read file."));
+
+            // Act & Assert
+            var exception = Assert.Throws<IOException>(() => DefaultRazorProjectEngine.ConvertToSourceDocument(projectItem.Object));
+            Assert.Equal("Couldn't read file.", exception.Message);
+        }
+
+        [Fact]
+        public void ConvertToSourceDocument_WithSuppressExceptions_UnreadableItem_DoesNotThrow()
+        {
+            // Arrange
+            var projectItem = new Mock<RazorProjectItem>(MockBehavior.Strict);
+            projectItem.SetupGet(p => p.Exists).Returns(true);
+            projectItem.SetupGet(p => p.PhysicalPath).Returns("path/to/file.cshtml");
+            projectItem.SetupGet(p => p.FilePath).Returns("path/to/file.cshtml");
+            projectItem.SetupGet(p => p.RelativePhysicalPath).Returns("path/to/file.cshtml");
+            projectItem.Setup(p => p.Read()).Throws(new IOException("Couldn't read file."));
+
+            // Act
+            var sourceDocument = DefaultRazorProjectEngine.ConvertToSourceDocument(projectItem.Object, suppressExceptions: true);
+
+            // Assert - Does not throw
+            Assert.NotNull(sourceDocument);
+            Assert.Equal(0, sourceDocument.Length);
+        }
     }
 }