Remove whitespace in sidebar when iterations disabled

app/views/shared/issuable/_sidebar.html.haml

@@ -7,6 +7,7 @@
 - can_edit_issuable = issuable_sidebar.dig(:current_user, :can_edit)
 - add_page_startup_api_call "#{issuable_sidebar[:issuable_json_path]}?serializer=sidebar_extras"
 - reviewers = local_assigns.fetch(:reviewers, nil)
+- in_group_context_with_iterations = @project.group.present? && issuable_sidebar[:supports_iterations]
 
 %aside.right-sidebar.js-right-sidebar.js-issuable-sidebar{ data: { signed: { in: signed_in }, issuable_type: issuable_type }, class: sidebar_gutter_collapsed_class, 'aria-live' => 'polite', 'aria-label': issuable_type }
   .issuable-sidebar
@@ -28,11 +29,11 @@
         = render_if_exists 'shared/issuable/sidebar_item_epic', issuable_sidebar: issuable_sidebar, group_path: @project.group.full_path, project_path: issuable_sidebar[:project_full_path], issue_iid: issuable_sidebar[:iid], issuable_type: issuable_type
 
       - if issuable_sidebar[:supports_milestone]
-        .block.milestone{ :class => ("gl-border-b-0!" if issuable_sidebar[:supports_iterations]), data: { qa_selector: 'milestone_block' } }
+        .block.milestone{ :class => ("gl-border-b-0!" if in_group_context_with_iterations), data: { qa_selector: 'milestone_block' } }
           .js-milestone-select{ data: { can_edit: can_edit_issuable.to_s, project_path: issuable_sidebar[:project_full_path], issue_iid: issuable_sidebar[:iid] } }
 
-      - if @project.group.present? && issuable_sidebar[:supports_iterations]
-        .block{ class: 'gl-pt-0!', data: { qa_selector: 'iteration_container' } }
+      - if in_group_context_with_iterations
+        .block{ class: 'gl-pt-0! gl-collapse-empty', data: { qa_selector: 'iteration_container', testid: 'iteration_container' } }<
           = render_if_exists 'shared/issuable/iteration_select', can_edit: can_edit_issuable.to_s, group_path: @project.group.full_path, project_path: issuable_sidebar[:project_full_path], issue_iid: issuable_sidebar[:iid], issuable_type: issuable_type
 
       - if issuable_sidebar[:supports_time_tracking]

ee/spec/views/shared/issuable/_sidebar.html.haml_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'shared/issuable/_iterations_dropdown.html.haml' do
+  let_it_be(:user) { create(:user) }
+
+  subject(:rendered) do
+    render 'shared/issuable/sidebar', issuable_sidebar: IssueSerializer.new(current_user: user)
+      .represent(issuable, serializer: 'sidebar'), assignees: []
+  end
+
+  context 'project in a group' do
+    let_it_be(:group) { create(:group) }
+    let_it_be(:project) { create(:project, group: group) }
+
+    before do
+      assign(:project, project)
+    end
+
+    context 'issuable that supports iterations' do
+      let(:issuable) { create(:issue, project: project) }
+
+      it 'shows iteration dropdown' do
+        expect(rendered).to have_css('[data-testid="iteration_container"]')
+      end
+    end
+
+    context 'issuable does not support iterations' do
+      let(:issuable) { create(:incident, project: project) }
+
+      it 'does not show iteration dropdown' do
+        expect(rendered).not_to have_css('[data-testid="iteration_container"]')
+      end
+    end
+  end
+
+  context 'non-group project' do
+    let_it_be(:project) { create(:project) }
+
+    let(:issuable) { create(:issue, project: project) }
+
+    before do
+      assign(:project, project)
+    end
+
+    it 'does not show iteration dropdown' do
+      expect(rendered).not_to have_css('[data-testid="iteration_container"]')
+    end
+  end
+end