Markdown is now correctly updated when config changes

packages/flutter_markdown/lib/src/markdown_raw.dart

@@ -129,10 +129,29 @@ class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {
 
   void initState() {
     super.initState();
+    _buildMarkdownCache();
+  }
+
+  void dispose() {
+    _linkHandler.dispose();
+    super.dispose();
+  }
+
+  void didUpdateConfig(MarkdownBodyRaw oldConfig) {
+    super.didUpdateConfig(oldConfig);
+
+    if (oldConfig.data != config.data ||
+        oldConfig.markdownStyle != config.markdownStyle ||
+        oldConfig.syntaxHighlighter != config.syntaxHighlighter ||
+        oldConfig.onTapLink != config.onTapLink)
+      _buildMarkdownCache();
+  }
 
+  void _buildMarkdownCache() {
     MarkdownStyleRaw markdownStyle = config.markdownStyle ?? config.createDefaultStyle(context);
     SyntaxHighlighter syntaxHighlighter = config.syntaxHighlighter ?? new _DefaultSyntaxHighlighter(markdownStyle.code);
 
+    _linkHandler?.dispose();
     _linkHandler = new _LinkHandler(config.onTapLink);
 
     // TODO: This can be optimized by doing the split and removing \r at the same time
@@ -143,11 +162,6 @@ class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {
     _cachedBlocks = renderer.render(document.parseLines(lines), markdownStyle, syntaxHighlighter, _linkHandler);
   }
 
-  void dispose() {
-    _linkHandler.dispose();
-    super.dispose();
-  }
-
   List<_Block> _cachedBlocks;
   _LinkHandler _linkHandler;
 
@@ -162,6 +176,10 @@ class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {
       children: blocks
     );
   }
+
+  void debugFillDescription(List<String> description) {
+    description.add('cached blocks identity: ${_cachedBlocks.hashCode}');
+  }
 }
 
 class _Renderer implements md.NodeVisitor {

packages/flutter_markdown/test/flutter_markdown_test.dart

@@ -94,6 +94,37 @@ void main() {
       expect(span.children[0].recognizer.runtimeType, equals(TapGestureRecognizer));
     });
   });
+
+  test("Changing config - data", () {
+    testWidgets((WidgetTester tester) {
+      tester.pumpWidget(new Markdown(data: "Data1"));
+      _expectTextStrings(_listElements(tester), <String>["Data1"]);
+
+      String stateBefore = WidgetFlutterBinding.instance.renderViewElement.toStringDeep();
+      tester.pumpWidget(new Markdown(data: "Data1"));
+      String stateAfter = WidgetFlutterBinding.instance.renderViewElement.toStringDeep();
+      expect(stateBefore, equals(stateAfter));
+
+      tester.pumpWidget(new Markdown(data: "Data2"));
+      _expectTextStrings(_listElements(tester), <String>["Data2"]);
+    });
+  });
+
+  test("Changing config - style", () {
+    testWidgets((WidgetTester tester) {
+      ThemeData theme = new ThemeData.light();
+
+      MarkdownStyle style1 = new MarkdownStyle.defaultFromTheme(theme);
+      MarkdownStyle style2 = new MarkdownStyle.largeFromTheme(theme);
+
+      tester.pumpWidget(new Markdown(data: "Test", markdownStyle: style1));
+
+      String stateBefore = WidgetFlutterBinding.instance.renderViewElement.toStringDeep();
+      tester.pumpWidget(new Markdown(data: "Test", markdownStyle: style2));
+      String stateAfter = WidgetFlutterBinding.instance.renderViewElement.toStringDeep();
+      expect(stateBefore, isNot(stateAfter));
+    });
+  });
 }
 
 List<Element> _listElements(WidgetTester tester) {