checklists: Do not add unnecessary \n

lib/core/checklist.dart

@@ -105,10 +105,9 @@ class Checklist {
   }
 
   void addItem(ChecklistItem item) {
+    _insertNewLineIfRequired(nodes.length - 1);
+
     items.add(item);
-    if (nodes.isNotEmpty && !nodes.last.textContent.endsWith('\n')) {
-      nodes.add(md.Text("\n"));
-    }
     nodes.add(item.element);
   }
 
@@ -126,9 +125,22 @@ class Checklist {
     var prevItem = items[index];
     var nodeIndex = nodes.indexOf(prevItem.element);
 
+    _insertNewLineIfRequired(nodeIndex);
+
     nodes.insert(nodeIndex, item.element);
     items.insert(index, item);
   }
+
+  void _insertNewLineIfRequired(int pos) {
+    if (nodes.isEmpty) return;
+
+    var node = nodes[pos];
+    if (node is md.Text) {
+      if (!node.text.endsWith('\n')) {
+        nodes.add(md.Text("\n"));
+      }
+    }
+  }
 }
 
 /// Copied from flutter-markdown - cannot be merged as we added xUpperCase and changed the regexp

test/checklist_test.dart

@@ -150,6 +150,26 @@ Booga Wooga
       expect(note.body, "Hi.\n[ ] item\n");
     });
 
+    test('Should not add \\n when adding after item', () async {
+      var content = "[ ] one";
+
+      var notePath = p.join(tempDir.path, "note13.md");
+      await File(notePath).writeAsString(content);
+
+      var parentFolder = NotesFolder(null, tempDir.path);
+      var note = Note(parentFolder, notePath);
+      await note.load();
+
+      var checklist = Checklist(note);
+      var items = checklist.items;
+      expect(items.length, equals(1));
+
+      checklist.addItem(checklist.buildItem(false, "item"));
+
+      note = checklist.note;
+      expect(note.body, "[ ] one\n[ ] item\n");
+    });
+
     test('insertItem works', () async {
       var content = "Hi.\n[ ] One\nTwo\n[ ] Three";