Ensure codeblocks support substitutions

docs/source/markup/substitutions.md

@@ -1,11 +1,22 @@
 ---
 title: Substitutions
 sub:
-  'frontmatter_key': "Front Matter Value"
+  frontmatter_key: "Front Matter Value"
+  version: 7.17.0
 ---
 
 Here are some variable substitutions:
 
 | Value               | Source       |
 | ------------------- | ------------ |
-| {{frontmatter_key}} | Front Matter |
+| {{frontmatter_key}} | Front Matter |
+
+Substitutions should work in code blocks too.
+
+```{code} sh
+wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz
+wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512
+shasum -a 512 -c elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512 <1>
+tar -xzf elasticsearch-{{version}}-linux-x86_64.tar.gz
+cd elasticsearch-{{version}}/ <2>
+```

src/Elastic.Markdown/Myst/Directives/DirectiveHtmlRenderer.cs

@@ -5,6 +5,7 @@
 // This file is licensed under the BSD-Clause 2 license.
 // See the license.txt file in the project root for more information.
 
+using Elastic.Markdown.Myst.Substitution;
 using Elastic.Markdown.Slices;
 using Elastic.Markdown.Slices.Directives;
 using Markdig;
@@ -255,6 +256,9 @@ void RenderLeaf(LeafBlock p)
 			renderer.EnableHtmlForInline = false;
 			foreach (var oo in p.Inline ?? [])
 			{
+
+				if (oo is SubstitutionLeaf sl)
+					renderer.Write(sl.Replacement);
 				if (oo is LiteralInline li)
 					renderer.Write(li);
 				if (oo is LineBreakInline)

tests/Elastic.Markdown.Tests/Inline/InlneBaseTests.cs

@@ -22,12 +22,7 @@ public override async Task InitializeAsync()
 	{
 		await base.InitializeAsync();
 		Block = Document
-			.Where(block => block is ParagraphBlock)
-			.Cast<ParagraphBlock>()
-			.FirstOrDefault()?
-			.Inline?
-			.Where(block => block is TDirective)
-			.Cast<TDirective>()
+			.Descendants<TDirective>()
 			.FirstOrDefault();
 	}
 

tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs

@@ -62,3 +62,26 @@ public void GeneratesAttributesInHtml() =>
 				"""{{valid-key}}"""
 			);
 }
+
+public class SubstitutionInCodeBlockTest(ITestOutputHelper output) : LeafTest<SubstitutionLeaf>(output,
+"""
+---
+sub:
+  version: "7.17.0"
+---
+```{code} sh
+wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz
+wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512
+shasum -a 512 -c elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512 <1>
+tar -xzf elasticsearch-{{version}}-linux-x86_64.tar.gz
+cd elasticsearch-{{version}}/ <2>
+```
+"""
+)
+{
+
+	[Fact]
+	public void GeneratesAttributesInHtml() =>
+		Html.Should().Contain("7.17.0");
+}
+