Implement DOC209 (Use 'see href' correctly)

Closes #13

DocumentationAnalyzers/DocumentationAnalyzers.Test.CSharp7/PortabilityRules/DOC209CSharp7UnitTests.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the MIT license. See LICENSE in the project root for license information.
+
+namespace DocumentationAnalyzers.Test.CSharp7.PortabilityRules
+{
+    using DocumentationAnalyzers.Test.PortabilityRules;
+
+    public class DOC209CSharp7UnitTests : DOC209UnitTests
+    {
+    }
+}

DocumentationAnalyzers/DocumentationAnalyzers.Test/PortabilityRules/DOC209UnitTests.cs

@@ -0,0 +1,115 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the MIT license. See LICENSE in the project root for license information.
+
+namespace DocumentationAnalyzers.Test.PortabilityRules
+{
+    using System.Threading.Tasks;
+    using Xunit;
+    using Verify = Microsoft.CodeAnalysis.CSharp.Testing.CSharpCodeFixVerifier<DocumentationAnalyzers.PortabilityRules.DOC209UseSeeHrefCorrectly, Microsoft.CodeAnalysis.Testing.EmptyCodeFixProvider, Microsoft.CodeAnalysis.Testing.Verifiers.XUnitVerifier>;
+
+    public class DOC209UnitTests
+    {
+        [Fact]
+        public async Task TestAbsoluteUriAsync()
+        {
+            var testCode = $@"
+/// <summary>
+/// <see href=""https://github.com""/>
+/// <see href=""https://github.com""></see>
+/// </summary>
+/// <seealso href=""https://github.com""/>
+/// <seealso href=""https://github.com""></see>
+class TestClass
+{{
+}}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+
+        [Fact]
+        public async Task TestRelativeUriAsync()
+        {
+            var testCode = $@"
+/// <summary>
+/// <see href=""docs/index.md""/>
+/// <see href=""docs/index.md""></see>
+/// </summary>
+/// <seealso href=""docs/index.md""/>
+/// <seealso href=""docs/index.md""></see>
+class TestClass
+{{
+}}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+
+        [Fact]
+        public async Task TestEscapesAllowedAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// <see href=""https://gith&#117;b.com""/>
+/// </summary>
+class TestClass
+{
+}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+
+        [Fact]
+        public async Task TestEmptyAndFullElementsValidatedAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// <see [|href|]=""https://""/>
+/// <see [|href|]=""https://""></see>
+/// </summary>
+/// <seealso [|href|]=""https://""/>
+/// <seealso [|href|]=""https://""></see>
+class TestClass
+{
+}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+
+        [Fact]
+        public async Task TestOtherAttributesIgnoredAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// <see Href=""https://""/>
+/// <see x:href=""https://""/>
+/// <see name=""https://""/>
+/// <see cref=""System.String""/>
+/// </summary>
+class TestClass
+{
+}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+
+        [Fact]
+        public async Task TestOtherElementsIgnoredAsync()
+        {
+            var testCode = @"
+/// <summary>
+/// <p:see href=""https://""/>
+/// </summary>
+/// <p:seealso href=""https://""/>
+class TestClass
+{
+}
+";
+
+            await Verify.VerifyAnalyzerAsync(testCode);
+        }
+    }
+}

DocumentationAnalyzers/DocumentationAnalyzers/Helpers/XmlCommentHelper.cs

@@ -42,6 +42,7 @@ internal static class XmlCommentHelper
         internal const string FileAttributeName = "file";
         internal const string PathAttributeName = "path";
         internal const string CrefArgumentName = "cref";
+        internal const string HrefArgumentName = "href";
         internal const string NameArgumentName = "name";
         internal const string LangwordArgumentName = "langword";
         internal const string TypeAttributeName = "type";

DocumentationAnalyzers/DocumentationAnalyzers/PortabilityRules/DOC209UseSeeHrefCorrectly.cs

@@ -0,0 +1,101 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the MIT license. See LICENSE in the project root for license information.
+
+namespace DocumentationAnalyzers.PortabilityRules
+{
+    using System;
+    using System.Collections.Immutable;
+    using System.Linq;
+    using DocumentationAnalyzers.Helpers;
+    using Microsoft.CodeAnalysis;
+    using Microsoft.CodeAnalysis.CSharp;
+    using Microsoft.CodeAnalysis.CSharp.Syntax;
+    using Microsoft.CodeAnalysis.Diagnostics;
+
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    [NoCodeFix("Cannot convert an invalid URI to one intended by the author.")]
+    internal class DOC209UseSeeHrefCorrectly : DiagnosticAnalyzer
+    {
+        /// <summary>
+        /// The ID for diagnostics produced by the <see cref="DOC209UseSeeHrefCorrectly"/> analyzer.
+        /// </summary>
+        public const string DiagnosticId = "DOC209";
+        private const string HelpLink = "https://github.com/DotNetAnalyzers/DocumentationAnalyzers/blob/master/docs/DOC209.md";
+
+        private static readonly LocalizableString Title = new LocalizableResourceString(nameof(PortabilityResources.DOC209Title), PortabilityResources.ResourceManager, typeof(PortabilityResources));
+        private static readonly LocalizableString MessageFormat = new LocalizableResourceString(nameof(PortabilityResources.DOC209MessageFormat), PortabilityResources.ResourceManager, typeof(PortabilityResources));
+        private static readonly LocalizableString Description = new LocalizableResourceString(nameof(PortabilityResources.DOC209Description), PortabilityResources.ResourceManager, typeof(PortabilityResources));
+
+        private static readonly DiagnosticDescriptor Descriptor =
+            new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, AnalyzerCategory.PortabilityRules, DiagnosticSeverity.Warning, AnalyzerConstants.EnabledByDefault, Description, HelpLink);
+
+        /// <inheritdoc/>
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }
+            = ImmutableArray.Create(Descriptor);
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+            context.EnableConcurrentExecution();
+
+            context.RegisterSyntaxNodeAction(HandleXmlNodeSyntax, SyntaxKind.XmlElement, SyntaxKind.XmlEmptyElement);
+        }
+
+        private static void HandleXmlNodeSyntax(SyntaxNodeAnalysisContext context)
+        {
+            var xmlNodeSyntax = (XmlNodeSyntax)context.Node;
+            var name = xmlNodeSyntax.GetName();
+            if (name is null || name.Prefix != null)
+            {
+                return;
+            }
+
+            if (name.LocalName.ValueText != XmlCommentHelper.SeeXmlTag
+                && name.LocalName.ValueText != XmlCommentHelper.SeeAlsoXmlTag)
+            {
+                return;
+            }
+
+            SyntaxList<XmlAttributeSyntax> attributes;
+            if (xmlNodeSyntax is XmlEmptyElementSyntax xmlEmptyElement)
+            {
+                attributes = xmlEmptyElement.Attributes;
+            }
+            else
+            {
+                attributes = ((XmlElementSyntax)xmlNodeSyntax).StartTag.Attributes;
+            }
+
+            foreach (var attribute in attributes)
+            {
+                if (attribute.Name is null || attribute.Name.Prefix != null)
+                {
+                    continue;
+                }
+
+                if (attribute.Name.LocalName.ValueText != XmlCommentHelper.HrefArgumentName)
+                {
+                    continue;
+                }
+
+                var text = ((XmlTextAttributeSyntax)attribute).TextTokens;
+                string valueText;
+                if (text.Count == 1)
+                {
+                    valueText = text[0].ValueText;
+                }
+                else
+                {
+                    valueText = string.Join(string.Empty, text.Select(textToken => textToken.ValueText));
+                }
+
+                if (Uri.TryCreate(valueText, System.UriKind.RelativeOrAbsolute, out _))
+                {
+                    continue;
+                }
+
+                context.ReportDiagnostic(Diagnostic.Create(Descriptor, attribute.Name.LocalName.GetLocation()));
+            }
+        }
+    }
+}

DocumentationAnalyzers/DocumentationAnalyzers/PortabilityRules/PortabilityResources.resx

@@ -186,4 +186,13 @@
   <data name="DOC207Title" xml:space="preserve">
     <value>Use 'see langword' correctly</value>
   </data>
+  <data name="DOC209Description" xml:space="preserve">
+    <value>'href' attribute value should be a URI</value>
+  </data>
+  <data name="DOC209MessageFormat" xml:space="preserve">
+    <value>'href' attribute value should be a URI</value>
+  </data>
+  <data name="DOC209Title" xml:space="preserve">
+    <value>Use 'see href' correctly</value>
+  </data>
 </root>

docs/DOC209.md

@@ -0,0 +1,32 @@
+# DOC209
+
+<table>
+<tr>
+  <td>TypeName</td>
+  <td>DOC209UseSeeHrefCorrectly</td>
+</tr>
+<tr>
+  <td>CheckId</td>
+  <td>DOC209</td>
+</tr>
+<tr>
+  <td>Category</td>
+  <td>Portability Rules</td>
+</tr>
+</table>
+
+## Cause
+
+The documentation contains a `<see href="..."/>` or `<seealso href="..."/>` element with an unrecognized URI.
+
+## Rule description
+
+*TODO*
+
+## How to fix violations
+
+*TODO*
+
+## How to suppress violations
+
+*TODO*

docs/PortabilityRules.md

@@ -10,3 +10,4 @@ Identifier | Name | Description
 [DOC203](DOC203.md) | UseBlockElementsCorrectly | The documentation contains a block element where a section or inline element was expected.
 [DOC204](DOC204.md) | UseInlineElementsCorrectly | The documentation contains an inline element where a section or block element was expected.
 [DOC207](DOC207.md) | UseSeeLangwordCorrectly | The documentation contains a `<see langword="..."/>` element with an unrecognized keyword.
+[DOC209](DOC209.md) | UseSeeHrefCorrectly | The documentation contains a `<see href="..."/>` element with an unrecognized URI.