Use the indexed checkbox to find line in the DOM58717-checkbox-in-issue-description-cannot-be-checked-if-the-description-contains-a-blockquote

4 files changed, 44 insertions, 12 deletions

diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 04dfcfbc22d..f363cb03a3f 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -272,7 +272,8 @@ class IssuableBaseService < BaseService
     tasklist_toggler = TaskListToggleService.new(issuable.description, issuable.description_html,
                                                  line_source: update_task_params[:line_source],
                                                  line_number: update_task_params[:line_number].to_i,
-                                                 toggle_as_checked: update_task_params[:checked])
+                                                 toggle_as_checked: update_task_params[:checked],
+                                                 index: update_task_params[:index])
 
     unless tasklist_toggler.execute
       # if we make it here, the data is much newer than we thought it was - fail fast
diff --git a/app/services/task_list_toggle_service.rb b/app/services/task_list_toggle_service.rb
index f6602a35033..800787e5c51 100644
--- a/app/services/task_list_toggle_service.rb
+++ b/app/services/task_list_toggle_service.rb
@@ -8,10 +8,11 @@
 class TaskListToggleService
   attr_reader :updated_markdown, :updated_markdown_html
 
-  def initialize(markdown, markdown_html, line_source:, line_number:, toggle_as_checked:)
+  def initialize(markdown, markdown_html, line_source:, line_number:, toggle_as_checked:, index:)
     @markdown, @markdown_html  = markdown, markdown_html
     @line_source, @line_number = line_source, line_number
     @toggle_as_checked         = toggle_as_checked
+    @index                     = index
 
     @updated_markdown, @updated_markdown_html = nil
   end
@@ -26,6 +27,7 @@ class TaskListToggleService
 
   attr_reader :markdown, :markdown_html, :toggle_as_checked
   attr_reader :line_source, :line_number
+  attr_reader :index
 
   def toggle_markdown
     source_lines      = markdown.split("\n")
@@ -64,9 +66,12 @@ class TaskListToggleService
     @updated_markdown_html = html.to_html
   end
 
-  # When using CommonMark, we should be able to use the embedded `sourcepos` attribute to
-  # target the exact line in the DOM.
+  # At the moment, we can't use the CommonMark `sourcepos`
+  #   html.css(".task-list-item[data-sourcepos^='#{line_number}:'] input.task-list-item-checkbox").first
+  # because special tags that change the line numbering (like the GitLab blockquote) will
+  # cause it to break.
+  # Use the indexed checkbox instead to target the exact line in the DOM.
   def get_html_checkbox(html)
-    html.css(".task-list-item[data-sourcepos^='#{line_number}:'] input.task-list-item-checkbox").first
+    html.css('.task-list-item-checkbox')[index - 1]
   end
 end
diff --git a/changelogs/unreleased/58717-checkbox-in-issue-description-cannot-be-checked-if-the-description-contains-a-blockquote.yml b/changelogs/unreleased/58717-checkbox-in-issue-description-cannot-be-checked-if-the-description-contains-a-blockquote.yml
new file mode 100644
index 00000000000..7c1dde260b7
--- /dev/null
+++ b/changelogs/unreleased/58717-checkbox-in-issue-description-cannot-be-checked-if-the-description-contains-a-blockquote.yml
@@ -0,0 +1,5 @@
+---
+title: Allow task lists that follow a blockquote to work correctly
+merge_request: 26748
+author:
+type: fixed
diff --git a/spec/services/task_list_toggle_service_spec.rb b/spec/services/task_list_toggle_service_spec.rb
index b1260cf740a..3c69757aac4 100644
--- a/spec/services/task_list_toggle_service_spec.rb
+++ b/spec/services/task_list_toggle_service_spec.rb
@@ -52,7 +52,7 @@ describe TaskListToggleService do
   it 'checks Task 1' do
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: true,
-                                  line_source: '* [ ] Task 1', line_number: 1)
+                                  line_source: '* [ ] Task 1', line_number: 1, index: 1)
 
     expect(toggler.execute).to be_truthy
     expect(toggler.updated_markdown.lines[0]).to eq "* [x] Task 1\n"
@@ -62,7 +62,7 @@ describe TaskListToggleService do
   it 'unchecks Item 1' do
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: false,
-                                  line_source: '1. [X] Item 1', line_number: 6)
+                                  line_source: '1. [X] Item 1', line_number: 6, index: 3)
 
     expect(toggler.execute).to be_truthy
     expect(toggler.updated_markdown.lines[5]).to eq "1. [ ] Item 1\n"
@@ -72,7 +72,7 @@ describe TaskListToggleService do
   it 'checks task in loose list' do
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: true,
-                                  line_source: '- [ ] loose list', line_number: 9)
+                                  line_source: '- [ ] loose list', line_number: 9, index: 5)
 
     expect(toggler.execute).to be_truthy
     expect(toggler.updated_markdown.lines[8]).to eq "- [x] loose list\n"
@@ -82,7 +82,7 @@ describe TaskListToggleService do
   it 'returns false if line_source does not match the text' do
     toggler = described_class.new(markdown, markdown_html,
                                   toggle_as_checked: false,
-                                  line_source: '* [x] Task Added', line_number: 2)
+                                  line_source: '* [x] Task Added', line_number: 2, index: 2)
 
     expect(toggler.execute).to be_falsey
   end
@@ -91,7 +91,7 @@ describe TaskListToggleService do
     rn_markdown = markdown.gsub("\n", "\r\n")
     toggler = described_class.new(rn_markdown, markdown_html,
                                   toggle_as_checked: true,
-                                  line_source: '* [ ] Task 1', line_number: 1)
+                                  line_source: '* [ ] Task 1', line_number: 1, index: 1)
 
     expect(toggler.execute).to be_truthy
     expect(toggler.updated_markdown.lines[0]).to eq "* [x] Task 1\r\n"
@@ -101,7 +101,7 @@ describe TaskListToggleService do
   it 'returns false if markdown is nil' do
     toggler = described_class.new(nil, markdown_html,
                                   toggle_as_checked: false,
-                                  line_source: '* [x] Task Added', line_number: 2)
+                                  line_source: '* [x] Task Added', line_number: 2, index: 2)
 
     expect(toggler.execute).to be_falsey
   end
@@ -109,8 +109,29 @@ describe TaskListToggleService do
   it 'returns false if markdown_html is nil' do
     toggler = described_class.new(markdown, nil,
                                   toggle_as_checked: false,
-                                  line_source: '* [x] Task Added', line_number: 2)
+                                  line_source: '* [x] Task Added', line_number: 2, index: 2)
 
     expect(toggler.execute).to be_falsey
   end
+
+  it 'properly handles a GitLab blockquote' do
+    markdown =
+      <<-EOT.strip_heredoc
+      >>>
+      gitlab blockquote
+      >>>
+
+      * [ ] Task 1
+      * [x] Task 2
+    EOT
+
+    markdown_html = Banzai::Pipeline::FullPipeline.call(markdown, project: nil)[:output].to_html
+    toggler = described_class.new(markdown, markdown_html,
+                                  toggle_as_checked: true,
+                                  line_source: '* [ ] Task 1', line_number: 5, index: 1)
+
+    expect(toggler.execute).to be_truthy
+    expect(toggler.updated_markdown.lines[4]).to eq "* [x] Task 1\n"
+    expect(toggler.updated_markdown_html).to include('disabled checked> Task 1')
+  end
 end