Reverting a merge request E2E test

app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_merged.vue

@@ -130,6 +130,7 @@ export default {
           size="small"
           category="secondary"
           variant="warning"
+          data-qa-selector="revert_button"
           @click="openRevertModal"
         >
           {{ revertLabel }}

qa/qa/page/merge_request/show.rb

@@ -108,6 +108,7 @@ module QA
         end
 
         view 'app/assets/javascripts/vue_merge_request_widget/components/states/mr_widget_merged.vue' do
+          element :revert_button
           element :cherry_pick_button
         end
 
@@ -368,6 +369,11 @@ module QA
           click_element(:cherry_pick_button, Page::Component::CommitModal)
           click_element(:submit_commit_button)
         end
+
+        def revert_change!
+          click_element(:revert_button, Page::Component::CommitModal)
+          click_element(:submit_commit_button)
+        end
       end
     end
   end

qa/qa/specs/features/browser_ui/3_create/merge_request/revert_spec.rb

+# frozen_string_literal: true
+
+module QA
+  RSpec.describe 'Create' do
+    describe 'Merged merge request' do
+      let(:project) do
+        Resource::Project.fabricate_via_api! do |project|
+          project.name = 'revert'
+        end
+      end
+
+      let(:revertable_merge_request) do
+        Resource::MergeRequest.fabricate_via_api! do |merge_request|
+          merge_request.project = project
+        end
+      end
+
+      before do
+        Flow::Login.sign_in
+      end
+
+      it 'can be reverted', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1745' do
+        revertable_merge_request.visit!
+
+        Page::MergeRequest::Show.perform do |merge_request|
+          merge_request.merge!
+          merge_request.revert_change!
+        end
+
+        Page::MergeRequest::New.perform(&:create_merge_request)
+
+        Page::MergeRequest::Show.perform do |merge_request|
+          merge_request.click_diffs_tab
+          expect(merge_request).to have_file(revertable_merge_request.file_name)
+        end
+      end
+    end
+  end
+end