highlighter: Add a tiny inline markdown case for debugging

Author: the-mikedavis

fixtures/highlighter/markdown_bold.md

@@ -0,0 +1,12 @@
+   This is a **bold** comment.
+//           ┡┛┡━━┛┗┹─ markup.bold punctuation.bracket
+//           │ ╰─ markup.bold
+//           ╰─ markup.bold punctuation.bracket
+   This is a [link containing a `code` snippet].
+//           ╿┡━━━━━━━━━━━━━━━━┛╿┡━━┛╿┡━━━━━━┛╰─ punctuation.bracket
+//           ││                 ││   │╰─ markup.link.text
+//           ││                 ││   ╰─ markup.link.text markup.raw.inline punctuation.bracket
+//           ││                 │╰─ markup.link.text markup.raw.inline
+//           ││                 ╰─ markup.link.text markup.raw.inline punctuation.bracket
+//           │╰─ markup.link.text
+//           ╰─ punctuation.bracket

highlighter/src/tests.rs

@@ -500,3 +500,12 @@ fn edit_remove_and_add_injection_layer() {
         .update(before_text.into(), PARSE_TIMEOUT, &[edit], &loader)
         .unwrap();
 }
+
+#[test]
+fn markdown_bold_highlight() {
+    let loader = TestLanguageLoader::new();
+    // This is a very simple case to check that adjacent equivalent highlights are merged
+    // properly: the `punctuation.bracket` highlight on the consecutive `*`s should be combined
+    // into one span.
+    highlight_fixture(&loader, "highlighter/markdown_bold.md");
+}