Fix #132: inline builder duplicates children

CHANGELOG.md

@@ -1,3 +1,11 @@
+## 1.0.9
+
+* Fixed custom inline `builders` (e.g. `a`) duplicating trailing text when the element had multiple children, such as link text containing a `_` or `*` delimiter that the parser splits into separate text nodes (#132)
+
+**Thanks to our contributors:**
+* [@Jess-Gabia](https://github.com/Jess-Gabia) for reporting the issue and identifying the fix (#132)
+* [@amungi](https://github.com/amungi) for confirming the fix in production
+
 ## 1.0.8
 
 * Fixed custom `builders` and `paddingBuilders` for the `hr` tag being ignored

lib/src/builder.dart

@@ -504,11 +504,13 @@ class MarkdownBuilder implements md.NodeVisitor {
           parent.style,
         );
         if (child != null) {
-          if (current.children.isEmpty) {
-            current.children.add(child);
-          } else {
-            current.children[0] = child;
-          }
+          // The returned widget represents the entire element, so discard all
+          // existing inline children — replacing only children[0] leaves any
+          // siblings (e.g. link text split on a `_`/`*` delimiter) to leak
+          // through to the parent and render twice. See issue #132.
+          current.children
+            ..clear()
+            ..add(child);
         }
       } else if (tag == 'img') {
         // create an image widget for this image

pubspec.yaml

@@ -5,7 +5,7 @@ description: A Markdown renderer for Flutter. Create rich text output,
 repository: https://github.com/foresightmobile/flutter_markdown_plus
 issue_tracker: https://github.com/foresightmobile/flutter_markdown_plus/issues
 documentation: https://github.com/foresightmobile/flutter_markdown_plus#readme
-version: 1.0.8
+version: 1.0.9
 
 environment:
   sdk: ^3.4.0

test/custom_syntax_test.dart

@@ -211,6 +211,48 @@ void defineTests() {
       expect(textWidget.data, 'foo');
     },
   );
+
+  testWidgets(
+    'inline builder replaces all children, not just the first (issue #132)',
+    (WidgetTester tester) async {
+      // The link text starts with an unpaired `_`, which the parser splits into
+      // multiple text nodes (`[Text("_"), Text("hello world")]`). A custom `a`
+      // builder returning a widget must replace *all* of them, otherwise the
+      // trailing "hello world" leaks through and renders twice.
+      await tester.pumpWidget(
+        boilerplate(
+          Markdown(
+            data: '[_hello world](https://example.com)',
+            builders: <String, MarkdownElementBuilder>{
+              'a': LinkTagBuilder(),
+            },
+          ),
+        ),
+      );
+
+      expect(find.text('LINK'), findsOneWidget);
+      expect(find.textContaining('hello world', findRichText: true), findsNothing);
+    },
+  );
+
+  testWidgets(
+    'inline builder replaces all children with a `*` delimiter (issue #132)',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        boilerplate(
+          Markdown(
+            data: '[*hello world](https://example.com)',
+            builders: <String, MarkdownElementBuilder>{
+              'a': LinkTagBuilder(),
+            },
+          ),
+        ),
+      );
+
+      expect(find.text('LINK'), findsOneWidget);
+      expect(find.textContaining('hello world', findRichText: true), findsNothing);
+    },
+  );
 }
 
 class SubscriptSyntax extends md.InlineSyntax {
@@ -371,6 +413,15 @@ class ImgBuilder extends MarkdownElementBuilder {
   }
 }
 
+class LinkTagBuilder extends MarkdownElementBuilder {
+  @override
+  Widget visitElementAfter(md.Element element, TextStyle? preferredStyle) {
+    // Deliberately returns a marker that does not contain the link text, so a
+    // test can assert the original children were fully replaced.
+    return const Text('LINK');
+  }
+}
+
 class NoteBuilder extends MarkdownElementBuilder {
   @override
   Widget? visitText(md.Text text, TextStyle? preferredStyle) {