[WCP]alt attribute for img tag (#9404)

* add image alter
NuGet · Feb 28, 2023 · 9fb61dc · 9fb61dc
1 parent 9e2d728
commit 9fb61dc
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/src/NuGetGallery/Services/MarkdownService.cs b/src/NuGetGallery/Services/MarkdownService.cs
@@ -25,6 +25,8 @@ public class MarkdownService : IMarkdownService
         private static readonly Regex EncodedBlockQuotePattern = new Regex("^ {0,3}&gt;", RegexOptions.Multiline, RegexTimeout);
         private static readonly Regex LinkPattern = new Regex("<a href=([\"\']).*?\\1", RegexOptions.None, RegexTimeout);
         private static readonly Regex HtmlCommentPattern = new Regex("<!--.*?-->", RegexOptions.Singleline, RegexTimeout);
+        private static readonly Regex ImageTextPattern = new Regex("!\\[\\]\\(", RegexOptions.Singleline, RegexTimeout);
+        private static readonly string altTextForImage = "alternate text is missing from this package README image";
 
         private readonly IFeatureFlagService _features;
         private readonly IImageDomainValidator _imageDomainValidator;
@@ -198,7 +200,9 @@ private RenderedMarkdownResult GetHtmlFromMarkdownMarkdig(string markdownString,
 
             var markdownWithoutComments = HtmlCommentPattern.Replace(markdownString, "");
 
-            var markdownWithoutBom = markdownWithoutComments.TrimStart('\ufeff');
+            var markdownWithImageAlt = ImageTextPattern.Replace(markdownWithoutComments, $"![{altTextForImage}](");
+
+            var markdownWithoutBom = markdownWithImageAlt.TrimStart('\ufeff');
 
             var pipeline = new MarkdownPipelineBuilder()
                 .UseGridTables()
@@ -284,8 +288,8 @@ private RenderedMarkdownResult GetHtmlFromMarkdownMarkdig(string markdownString,
 
                 renderer.Render(document);
                 output.Content = htmlWriter.ToString().Trim();
-
                 output.IsMarkdigMdSyntaxHighlightEnabled = _features.IsMarkdigMdSyntaxHighlightEnabled();
+
                 return output;
             }
         }

diff --git a/tests/NuGetGallery.Facts/Services/MarkdownServiceFacts.cs b/tests/NuGetGallery.Facts/Services/MarkdownServiceFacts.cs
@@ -103,6 +103,8 @@ public void EncodesHtmlInMarkdownWithAdaptiveHeader(string originalMd, string ex
             [InlineData("![image](https://www.asp.net/fake.jpg)", "<p><img src=\"https://www.asp.net/fake.jpg\" alt=\"image\" /></p>", false, false)]
             [InlineData("![image](http://www.otherurl.net/fake.jpg)", "<p><img src=\"https://www.otherurl.net/fake.jpg\" class=\"img-fluid\" alt=\"image\" /></p>", true, true)]
             [InlineData("![image](http://www.otherurl.net/fake.jpg)", "<p><img src=\"https://www.otherurl.net/fake.jpg\" alt=\"image\" /></p>", true, false)]
+            [InlineData("![](http://www.otherurl.net/fake.jpg)", "<p><img src=\"https://www.otherurl.net/fake.jpg\" alt=\"\" /></p>", true, false)]
+            [InlineData("![](http://www.otherurl.net/fake.jpg)", "<p><img src=\"https://www.otherurl.net/fake.jpg\" class=\"img-fluid\" alt=\"alternate text is missing from this package README image\" /></p>", true, true)]
             [InlineData("## License\n\tLicensed under the Apache License, Version 2.0 (the \"License\");", "<h3 id=\"license\">License</h3>\n<pre><code>Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);\n</code></pre>", false, true)]
             [InlineData("## License\n\tLicensed under the Apache License, Version 2.0 (the \"License\");", "<h3 id=\"license\">License</h3>\n<pre><code>Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);\n</code></pre>", false, true)]
             public void ConvertsMarkdownToHtml(string originalMd, string expectedHtml, bool imageRewriteExpected, bool isMarkdigMdRenderingEnabled)