Adjust task regex to detect task in list item

that has no text

app/models/concerns/taskable.rb

@@ -15,11 +15,11 @@ module Taskable
   INCOMPLETE_PATTERN = /(\[[\s]\])/.freeze
   ITEM_PATTERN       = %r{
     ^
-    (?:(?:>\s{0,4})*)         # optional blockquote characters
-    \s*(?:[-+*]|(?:\d+\.))    # list prefix required - task item has to be always in a list
-    \s+                       # whitespace prefix has to be always presented for a list item
-    (\[\s\]|\[[xX]\])         # checkbox
-    (\s.+)                    # followed by whitespace and some text.
+    (?:(?:>\s{0,4})*)          # optional blockquote characters
+    (?:\s*(?:[-+*]|(?:\d+\.)))+  # list prefix (one or more) required - task item has to be always in a list
+    \s+                        # whitespace prefix has to be always presented for a list item
+    (\[\s\]|\[[xX]\])          # checkbox
+    (\s.+)                     # followed by whitespace and some text.
   }x.freeze
 
   def self.get_tasks(content)

changelogs/unreleased/27296-incorrect-task-list-checked-with-embedded-subtasks.yml

+---
+title: Properly check a task embedded in a list with no text
+merge_request: 21947
+author:
+type: fixed

spec/services/task_list_toggle_service_spec.rb

@@ -121,7 +121,7 @@ describe TaskListToggleService do
       > * [x] Task 2
     EOT
 
-    markdown_html = Banzai::Pipeline::FullPipeline.call(markdown, project: nil)[:output].to_html
+    markdown_html = parse_markdown(markdown)
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: true,
                                   line_source: '> > * [ ] Task 1', line_number: 1)
@@ -142,7 +142,7 @@ describe TaskListToggleService do
       * [x] Task 2
     EOT
 
-    markdown_html = Banzai::Pipeline::FullPipeline.call(markdown, project: nil)[:output].to_html
+    markdown_html = parse_markdown(markdown)
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: true,
                                   line_source: '* [ ] Task 1', line_number: 5)
@@ -151,4 +151,44 @@ describe TaskListToggleService do
     expect(toggler.updated_markdown.lines[4]).to eq "* [x] Task 1\n"
     expect(toggler.updated_markdown_html).to include('disabled checked> Task 1')
   end
+
+  context 'when clicking an embedded subtask' do
+    it 'properly handles it inside an unordered list' do
+      markdown =
+        <<-EOT.strip_heredoc
+      - - [ ] Task 1
+        - [x] Task 2
+      EOT
+
+      markdown_html = parse_markdown(markdown)
+      toggler = described_class.new(markdown, markdown_html,
+                                    toggle_as_checked: true,
+                                    line_source: '- - [ ] Task 1', line_number: 1)
+
+      expect(toggler.execute).to be_truthy
+      expect(toggler.updated_markdown.lines[0]).to eq "- - [x] Task 1\n"
+      expect(toggler.updated_markdown_html).to include('disabled checked> Task 1')
+    end
+
+    it 'properly handles it inside an ordered list' do
+      markdown =
+        <<-EOT.strip_heredoc
+      1. - [ ] Task 1
+         - [x] Task 2
+      EOT
+
+      markdown_html = parse_markdown(markdown)
+      toggler = described_class.new(markdown, markdown_html,
+                                    toggle_as_checked: true,
+                                    line_source: '1. - [ ] Task 1', line_number: 1)
+
+      expect(toggler.execute).to be_truthy
+      expect(toggler.updated_markdown.lines[0]).to eq "1. - [x] Task 1\n"
+      expect(toggler.updated_markdown_html).to include('disabled checked> Task 1')
+    end
+  end
+
+  def parse_markdown(markdown)
+    Banzai::Pipeline::FullPipeline.call(markdown, project: nil)[:output].to_html
+  end
 end