Merge pull request #876 from Akarinnnnn/fix-872

Fix #872 by reserve null title string.

src/Markdig.Tests/TestLinkHelper.cs

@@ -112,26 +112,26 @@ public class TestLinkHelper
     }
 
     [Test]
-    public void TestUrlAndTitleEmpty()
+    public void TestUrlEmptyAndTitleNull()
     {
         //                           01234
         var text = new StringSlice(@"(<>)A");
         Assert.True(LinkHelper.TryParseInlineLink(ref text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan));
         Assert.AreEqual(string.Empty, link);
-        Assert.AreEqual(string.Empty, title);
+        Assert.AreEqual(null, title);
         Assert.AreEqual(new SourceSpan(1, 2), linkSpan);
         Assert.AreEqual(SourceSpan.Empty, titleSpan);
         Assert.AreEqual('A', text.CurrentChar);
     }
 
     [Test]
-    public void TestUrlAndTitleEmpty2()
+    public void TestUrlEmptyAndTitleNull2()
     {
         //                           012345
         var text = new StringSlice(@"( <> )A");
         Assert.True(LinkHelper.TryParseInlineLink(ref text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan));
         Assert.AreEqual(string.Empty, link);
-        Assert.AreEqual(string.Empty, title);
+        Assert.AreEqual(null, title);
         Assert.AreEqual(new SourceSpan(2, 3), linkSpan);
         Assert.AreEqual(SourceSpan.Empty, titleSpan);
         Assert.AreEqual('A', text.CurrentChar);
@@ -158,7 +158,7 @@ public class TestLinkHelper
         var text = new StringSlice(@"()A");
         Assert.True(LinkHelper.TryParseInlineLink(ref text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan));
         Assert.AreEqual(string.Empty, link);
-        Assert.AreEqual(string.Empty, title);
+        Assert.AreEqual(null, title);
         Assert.AreEqual(SourceSpan.Empty, linkSpan);
         Assert.AreEqual(SourceSpan.Empty, titleSpan);
         Assert.AreEqual('A', text.CurrentChar);

src/Markdig.Tests/TestPlainText.cs

@@ -26,6 +26,14 @@ public class TestPlainText
         Assert.AreEqual(expected, actual);
     }
 
+    [Test]
+    [TestCase(/* markdownText: */ "```\nConsole.WriteLine(\"Hello, World!\");\n```", /* expected: */ "Console.WriteLine(\"Hello, World!\");\n")]
+    public void TestPlainCodeBlock(string markdownText, string expected)
+    {
+        var actual = Markdown.ToPlainText(markdownText);
+        Assert.AreEqual(expected, actual);
+    }
+
     [Test]
     [TestCase(/* markdownText: */ ":::\nfoo\n:::", /* expected: */ "foo\n", /*extensions*/ "customcontainers|advanced")]
     [TestCase(/* markdownText: */ ":::bar\nfoo\n:::", /* expected: */ "foo\n", /*extensions*/ "customcontainers+attributes|advanced")]

src/Markdig/Helpers/LinkHelper.cs

@@ -411,7 +411,7 @@ public static class LinkHelper
         {
             // Skip ')'
             text.SkipChar();
-            title ??= string.Empty;
+            // not to normalize nulls into empty strings, since LinkInline.Title property is nullable.
         }
 
         return isValid;
@@ -1565,4 +1565,4 @@ public static class LinkHelper
         label = buffer.ToString();
         return true;
     }
-}
+}

src/Markdig/Parsers/Inlines/LinkInlineParser.cs

@@ -260,7 +260,7 @@ public class LinkInlineParser : InlineParser
                     link = new LinkInline()
                     {
                         Url = HtmlHelper.Unescape(url, removeBackSlash: false),
-                        Title = HtmlHelper.Unescape(title, removeBackSlash: false),
+                        Title = title is null ? null : HtmlHelper.Unescape(title, removeBackSlash: false),
                         IsImage = openParent.IsImage,
                         LabelSpan = openParent.LabelSpan,
                         UrlSpan = inlineState.GetSourcePositionFromLocalSpan(linkSpan),

src/Markdig/Renderers/Html/CodeBlockRenderer.cs

@@ -100,7 +100,7 @@ public class CodeBlockRenderer : HtmlObjectRenderer<CodeBlock>
                 renderer.WriteRaw('>');
             }
 
-            renderer.WriteLeafRawLines(obj, true, true);
+            renderer.WriteLeafRawLines(obj, true, renderer.EnableHtmlEscape);
 
             if (renderer.EnableHtmlForBlock)
             {