Creating UrlUtility for IsLocalUrl, and cleaning up UrlHelper

src/Microsoft.AspNet.Mvc.Core/IUrlHelper.cs

@@ -33,10 +33,24 @@ namespace Microsoft.AspNet.Mvc
         string Content(string contentPath);
 
         /// <summary>
-        /// Returns a value that indicates whether the URL is local.
+        /// Returns a value that indicates whether the URL is local. An URL with an absolute path is considered local
+        /// if it does not have a host/authority part. URLs using the virtual paths ('~/') are also local.
         /// </summary>
         /// <param name="url">The URL.</param>
-        /// <returns>true if the URL is local; otherwise, false.</returns>
+        /// <returns><c>true</c> if the URL is local; otherwise, <c>false</c>.</returns>
+        /// <example>
+        /// <para>
+        /// For example, the following URLs are considered local:
+        /// /Views/Default/Index.html
+        /// ~/Index.html
+        /// </para>
+        /// <para>
+        /// The following URLs are non-local:
+        /// ../Index.html
+        /// http://www.contoso.com/
+        /// http://localhost/Index.html
+        /// </para>
+        /// </example>
         bool IsLocalUrl(string url);
 
         /// <summary>

src/Microsoft.AspNet.Mvc.Core/Internal/UrlUtility.cs

@@ -0,0 +1,39 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNet.Mvc.Internal
+{
+    public static class UrlUtility
+    {
+        /// <summary>
+        /// Returns a value that indicates whether the URL is local. An URL with an absolute path is considered local
+        /// if it does not have a host/authority part. URLs using the virtual paths ('~/') are also local.
+        /// </summary>
+        /// <param name="url">The URL.</param>
+        /// <returns><c>true</c> if the URL is local; otherwise, <c>false</c>.</returns>
+        /// <example>
+        /// <para>
+        /// For example, the following URLs are considered local:
+        /// /Views/Default/Index.html
+        /// ~/Index.html
+        /// </para>
+        /// <para>
+        /// The following URLs are non-local:
+        /// ../Index.html
+        /// http://www.contoso.com/
+        /// http://localhost/Index.html
+        /// </para>
+        /// </example>
+        public static bool IsLocalUrl(string url)
+        {
+            return
+                !string.IsNullOrEmpty(url) &&
+
+                // Allows "/" or "/foo" but not "//" or "/\".
+                ((url[0] == '/' && (url.Length == 1 || (url[1] != '/' && url[1] != '\\'))) ||
+
+                // Allows "~/" or "~/foo".
+                (url.Length > 1 && url[0] == '~' && url[1] == '/'));
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Core/UrlHelper.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.Internal;
 using Microsoft.AspNet.Routing;
 using Microsoft.Framework.DependencyInjection;
 
@@ -71,14 +72,7 @@ namespace Microsoft.AspNet.Mvc
         /// <inheritdoc />
         public bool IsLocalUrl(string url)
         {
-            return
+            return UrlUtility.IsLocalUrl(url);
-                !string.IsNullOrEmpty(url) &&
-
-                // Allows "/" or "/foo" but not "//" or "/\".
-                ((url[0] == '/' && (url.Length == 1 || (url[1] != '/' && url[1] != '\\'))) ||
-
-                // Allows "~/" or "~/foo".
-                (url.Length > 1 && url[0] == '~' && url[1] == '/'));
         }
 
         /// <inheritdoc />

test/Microsoft.AspNet.Mvc.Core.Test/UrlHelperTest.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Mvc.Internal;
 using Microsoft.AspNet.Routing;
 using Microsoft.Framework.DependencyInjection;
 using Microsoft.Framework.Logging;
@@ -58,9 +59,13 @@ namespace Microsoft.AspNet.Mvc.Core.Test
             Assert.Equal(expectedPath, path);
         }
 
+        // UrlHelper.IsLocalUrl depends on the UrlUtility.IsLocalUrl method. 
+        // To avoid duplicate tests, all the tests exercising IsLocalUrl verify  
+        // both of UrlHelper.IsLocalUrl and UrlUtility.IsLocalUrl
         [Theory]
         [InlineData(null)]
         [InlineData("")]
+        [InlineData(" ")]
         public void IsLocalUrl_ReturnsFalseOnEmpty(string url)
         {
             // Arrange
@@ -71,6 +76,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -87,6 +98,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.True(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.True(result);
         }
 
         [Theory]
@@ -102,6 +119,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.True(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.True(result);
         }
 
         [Theory]
@@ -118,6 +141,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -135,6 +164,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -150,6 +185,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -165,6 +206,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -179,6 +226,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -196,6 +249,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -214,6 +273,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -233,6 +298,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Theory]
@@ -250,6 +321,12 @@ namespace Microsoft.AspNet.Mvc.Core.Test
 
             // Assert
             Assert.False(result);
+
+            // Arrange & Act
+            result = UrlUtility.IsLocalUrl(url);
+
+            // Assert
+            Assert.False(result);
         }
 
         [Fact]