Add a test for the markdown node parsing

This way we will clearly know when the Markdown parsing fails because of
bugs in the markdown package.

lib/widgets/note_viewer.dart

@@ -55,12 +55,6 @@ class NoteViewer extends StatelessWidget {
       ),
     );
 
-    // It's important to add both these inline syntaxes before the other
-    // syntaxes as the LinkSyntax intefers with both of these
-    var markdownExtensions = md.ExtensionSet.gitHubFlavored;
-    markdownExtensions.inlineSyntaxes.insert(0, WikiLinkSyntax());
-    markdownExtensions.inlineSyntaxes.insert(1, TaskListSyntax());
-
     final rootFolder = Provider.of<NotesFolderFS>(context);
     var view = EditorScrollView(
       child: Column(
@@ -116,7 +110,7 @@ class NoteViewer extends StatelessWidget {
               },
               imageBuilder: (url, title, alt) => kDefaultImageBuilder(
                   url, note.parent.folderPath + p.separator, null, null),
-              extensionSet: markdownExtensions,
+              extensionSet: markdownExtensions(),
             ),
           ),
           const SizedBox(height: 16.0),
@@ -131,6 +125,15 @@ class NoteViewer extends StatelessWidget {
     return view;
   }
 
+  static md.ExtensionSet markdownExtensions() {
+    // It's important to add both these inline syntaxes before the other
+    // syntaxes as the LinkSyntax intefers with both of these
+    var markdownExtensions = md.ExtensionSet.gitHubFlavored;
+    markdownExtensions.inlineSyntaxes.insert(0, WikiLinkSyntax());
+    markdownExtensions.inlineSyntaxes.insert(1, TaskListSyntax());
+    return markdownExtensions;
+  }
+
   /*
   Widget _buildFooter(BuildContext context) {
     return Padding(

test/markdown_rendering_test.dart

@@ -0,0 +1,26 @@
+import 'package:test/test.dart';
+import 'package:markdown/markdown.dart' as md;
+
+import 'package:gitjournal/widgets/note_viewer.dart';
+
+void main() {
+  test('Parses Wiki Lnks and task items', () {
+    var body = "[[GitJournal]] should match.\n- [ ] task item";
+    var lines = body.split('\n');
+
+    var doc = md.Document(
+      encodeHtml: false,
+      extensionSet: NoteViewer.markdownExtensions(),
+      inlineSyntaxes: NoteViewer.markdownExtensions().inlineSyntaxes,
+    );
+    var nodes = doc.parseLines(lines);
+
+    var expected =
+        """<p><a type="wiki" href="[[GitJournal]]" term="GitJournal">GitJournal</a> should match.</p>
+<ul>
+<li><input type="checkbox" disabled="true" checked="false"></input>task item</li>
+</ul>""";
+
+    expect(md.renderToHtml(nodes), expected);
+  });
+}