Add clone issue to REST API

Issue cloning available at POST /projects/:id/issues/:issue_iid/clone

Changelog: added
Co-authored-by: Mario Celi <mcelicalderon@gitlab.com>

doc/api/issues.md

@@ -1487,6 +1487,113 @@ NOTE:
 The `closed_by` attribute was [introduced in GitLab 10.6](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/17042). This value is only present for issues closed after GitLab 10.6 and if the user account that closed
 the issue still exists.
 
+## Clone an issue
+
+Clone the issue to given project. If the user has insufficient permissions,
+an error message with status code `400` is returned.
+
+Copies as much data as possible as long as the target project contains equivalent labels, milestones,
+and so on.
+
+```plaintext
+POST /projects/:id/issues/:issue_iid/clone
+```
+
+| Attribute       | Type           | Required               | Description                       |
+| --------------- | -------------- | ---------------------- | --------------------------------- |
+| `id`            | integer/string | **{check-circle}** Yes | ID or [URL-encoded path of the project](index.md#namespaced-path-encoding) owned by the authenticated user. |
+| `issue_iid`     | integer        | **{check-circle}** Yes | Internal ID of a project's issue. |
+| `to_project_id` | integer        | **{check-circle}** Yes | ID of the new project.            |
+| `with_notes`    | boolean        | **{dotted-circle}** No | Clone the issue with [notes](notes.md). Default is `false`. |
+
+```shell
+curl --request POST \
+--header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/projects/5/issues/1/clone?with_notes=true&to_project_id=6"
+```
+
+Example response:
+
+```json
+{
+  "id":290,
+  "iid":1,
+  "project_id":143,
+  "title":"foo",
+  "description":"closed",
+  "state":"opened",
+  "created_at":"2021-09-14T22:24:11.696Z",
+  "updated_at":"2021-09-14T22:24:11.696Z",
+  "closed_at":null,
+  "closed_by":null,
+  "labels":[
+
+  ],
+  "milestone":null,
+  "assignees":[
+    {
+      "id":179,
+      "name":"John Doe2",
+      "username":"john",
+      "state":"active",
+      "avatar_url":"https://www.gravatar.com/avatar/10fc7f102be8de7657fb4d80898bbfe3?s=80\u0026d=identicon",
+      "web_url":"https://gitlab.example.com/john"
+    }
+  ],
+  "author":{
+    "id":179,
+    "name":"John Doe2",
+    "username":"john",
+    "state":"active",
+    "avatar_url":"https://www.gravatar.com/avatar/10fc7f102be8de7657fb4d80898bbfe3?s=80\u0026d=identicon",
+    "web_url":"https://gitlab.example.com/john"
+  },
+  "type":"ISSUE",
+  "assignee":{
+    "id":179,
+    "name":"John Doe2",
+    "username":"john",
+    "state":"active",
+    "avatar_url":"https://www.gravatar.com/avatar/10fc7f102be8de7657fb4d80898bbfe3?s=80\u0026d=identicon",
+    "web_url":"https://gitlab.example.com/john"
+  },
+  "user_notes_count":1,
+  "merge_requests_count":0,
+  "upvotes":0,
+  "downvotes":0,
+  "due_date":null,
+  "confidential":false,
+  "discussion_locked":null,
+  "issue_type":"issue",
+  "web_url":"https://gitlab.example.com/namespace1/project2/-/issues/1",
+  "time_stats":{
+    "time_estimate":0,
+    "total_time_spent":0,
+    "human_time_estimate":null,
+    "human_total_time_spent":null
+  },
+  "task_completion_status":{
+    "count":0,
+    "completed_count":0
+  },
+  "blocking_issues_count":0,
+  "has_tasks":false,
+  "_links":{
+    "self":"https://gitlab.example.com/api/v4/projects/143/issues/1",
+    "notes":"https://gitlab.example.com/api/v4/projects/143/issues/1/notes",
+    "award_emoji":"https://gitlab.example.com/api/v4/projects/143/issues/1/award_emoji",
+    "project":"https://gitlab.example.com/api/v4/projects/143"
+  },
+  "references":{
+    "short":"#1",
+    "relative":"#1",
+    "full":"namespace1/project2#1"
+  },
+  "subscribed":true,
+  "moved_to_id":null,
+  "service_desk_reply_to":null
+}
+```
+
 ## Subscribe to an issue
 
 Subscribes the authenticated user to an issue to receive notifications.

lib/api/issues.rb

@@ -375,6 +375,34 @@ module API
       end
       # rubocop: enable CodeReuse/ActiveRecord
 
+      desc 'Clone an existing issue' do
+        success Entities::Issue
+      end
+      params do
+        requires :issue_iid, type: Integer, desc: 'The internal ID of a project issue'
+        requires :to_project_id, type: Integer, desc: 'The ID of the new project'
+        optional :with_notes, type: Boolean, desc: 'Clone issue with notes', default: false
+      end
+      # rubocop: disable CodeReuse/ActiveRecord
+      post ':id/issues/:issue_iid/clone' do
+        Gitlab::QueryLimiting.disable!('https://gitlab.com/gitlab-org/gitlab/-/issues/340252')
+
+        issue = user_project.issues.find_by(iid: params[:issue_iid])
+        not_found!('Issue') unless issue
+
+        target_project = Project.find_by(id: params[:to_project_id])
+        not_found!('Project') unless target_project
+
+        begin
+          issue = ::Issues::CloneService.new(project: user_project, current_user: current_user)
+            .execute(issue, target_project, with_notes: params[:with_notes])
+          present issue, with: Entities::Issue, current_user: current_user, project: target_project
+        rescue ::Issues::CloneService::CloneError => error
+          render_api_error!(error.message, 400)
+        end
+      end
+      # rubocop: enable CodeReuse/ActiveRecord
+
       desc 'Delete a project issue'
       params do
         requires :issue_iid, type: Integer, desc: 'The internal ID of a project issue'

spec/requests/api/issues/post_projects_issues_spec.rb

@@ -8,15 +8,15 @@ RSpec.describe API::Issues do
     create(:project, :public, creator_id: user.id, namespace: user.namespace)
   end
 
-  let(:user2)             { create(:user) }
-  let(:non_member)        { create(:user) }
+  let_it_be(:user2) { create(:user) }
+  let_it_be(:non_member) { create(:user) }
   let_it_be(:guest) { create(:user) }
   let_it_be(:author) { create(:author) }
+  let_it_be(:milestone) { create(:milestone, title: '1.0.0', project: project) }
   let_it_be(:assignee) { create(:assignee) }
-  let(:admin)             { create(:user, :admin) }
-  let(:issue_title)       { 'foo' }
-  let(:issue_description) { 'closed' }
-  let!(:closed_issue) do
+  let_it_be(:admin) { create(:user, :admin) }
+
+  let_it_be(:closed_issue) do
     create :closed_issue,
       author: user,
       assignees: [user],
@@ -28,7 +28,7 @@ RSpec.describe API::Issues do
       closed_at: 1.hour.ago
   end
 
-  let!(:confidential_issue) do
+  let_it_be(:confidential_issue) do
     create :issue,
       :confidential,
       project: project,
@@ -38,7 +38,7 @@ RSpec.describe API::Issues do
       updated_at: 2.hours.ago
   end
 
-  let!(:issue) do
+  let_it_be(:issue) do
     create :issue,
       author: user,
       assignees: [user],
@@ -46,22 +46,21 @@ RSpec.describe API::Issues do
       milestone: milestone,
       created_at: generate(:past_time),
       updated_at: 1.hour.ago,
-      title: issue_title,
-      description: issue_description
+      title: 'foo',
+      description: 'closed'
   end
 
+  let_it_be(:note) { create(:note_on_issue, author: user, project: project, noteable: issue) }
+
   let_it_be(:label) do
     create(:label, title: 'label', color: '#FFAABB', project: project)
   end
 
   let!(:label_link) { create(:label_link, label: label, target: issue) }
-  let(:milestone) { create(:milestone, title: '1.0.0', project: project) }
   let_it_be(:empty_milestone) do
     create(:milestone, title: '2.0.0', project: project)
   end
 
-  let!(:note) { create(:note_on_issue, author: user, project: project, noteable: issue) }
-
   let(:no_milestone_title) { 'None' }
   let(:any_milestone_title) { 'Any' }
 
@@ -556,6 +555,114 @@ RSpec.describe API::Issues do
     end
   end
 
+  describe '/projects/:id/issues/:issue_iid/clone' do
+    let_it_be(:valid_target_project) { create(:project) }
+    let_it_be(:invalid_target_project) { create(:project) }
+
+    before_all do
+      valid_target_project.add_maintainer(user)
+    end
+
+    context 'when user can admin the issue' do
+      context 'when the user can admin the target project' do
+        it 'clones the issue' do
+          expect do
+            post_clone_issue(user, issue, valid_target_project)
+          end.to change { valid_target_project.issues.count }.by(1)
+
+          cloned_issue = Issue.last
+
+          expect(cloned_issue.notes.count).to eq(2)
+          expect(cloned_issue.notes.pluck(:note)).not_to include(issue.notes.first.note)
+          expect(response).to have_gitlab_http_status(:created)
+          expect(json_response['id']).to eq(cloned_issue.id)
+          expect(json_response['project_id']).to eq(valid_target_project.id)
+        end
+
+        context 'when target project is the same source project' do
+          it 'clones the issue' do
+            expect do
+              post_clone_issue(user, issue, issue.project)
+            end.to change { issue.reset.project.issues.count }.by(1)
+
+            cloned_issue = Issue.last
+
+            expect(cloned_issue.notes.count).to eq(2)
+            expect(cloned_issue.notes.pluck(:note)).not_to include(issue.notes.first.note)
+            expect(response).to have_gitlab_http_status(:created)
+            expect(json_response['id']).to eq(cloned_issue.id)
+            expect(json_response['project_id']).to eq(issue.project.id)
+          end
+        end
+      end
+    end
+
+    context 'when the user does not have the permission to clone issues' do
+      it 'returns 400' do
+        post api("/projects/#{project.id}/issues/#{issue.iid}/clone", user),
+          params: { to_project_id: invalid_target_project.id }
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+        expect(json_response['message']).to eq(s_('CloneIssue|Cannot clone issue due to insufficient permissions!'))
+      end
+    end
+
+    context 'when using the issue ID instead of iid' do
+      it 'returns 404' do
+        post api("/projects/#{project.id}/issues/#{issue.id}/clone", user),
+          params: { to_project_id: valid_target_project.id }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 Issue Not Found')
+      end
+    end
+
+    context 'when issue does not exist' do
+      it 'returns 404' do
+        post api("/projects/#{project.id}/issues/12300/clone", user),
+          params: { to_project_id: valid_target_project.id }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 Issue Not Found')
+      end
+    end
+
+    context 'when source project does not exist' do
+      it 'returns 404' do
+        post api("/projects/0/issues/#{issue.iid}/clone", user),
+          params: { to_project_id: valid_target_project.id }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 Project Not Found')
+      end
+    end
+
+    context 'when target project does not exist' do
+      it 'returns 404' do
+        post api("/projects/#{project.id}/issues/#{issue.iid}/clone", user),
+          params: { to_project_id: 0 }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response['message']).to eq('404 Project Not Found')
+      end
+    end
+
+    it 'clones the issue with notes when with_notes is true' do
+      expect do
+        post api("/projects/#{project.id}/issues/#{issue.iid}/clone", user),
+          params: { to_project_id: valid_target_project.id, with_notes: true }
+      end.to change { valid_target_project.issues.count }.by(1)
+
+      cloned_issue = Issue.last
+
+      expect(cloned_issue.notes.count).to eq(3)
+      expect(cloned_issue.notes.pluck(:note)).to include(issue.notes.first.note)
+      expect(response).to have_gitlab_http_status(:created)
+      expect(json_response['id']).to eq(cloned_issue.id)
+      expect(json_response['project_id']).to eq(valid_target_project.id)
+    end
+  end
+
   describe 'POST :id/issues/:issue_iid/subscribe' do
     it 'subscribes to an issue' do
       post api("/projects/#{project.id}/issues/#{issue.iid}/subscribe", user2)
@@ -621,4 +728,9 @@ RSpec.describe API::Issues do
       expect(response).to have_gitlab_http_status(:not_found)
     end
   end
+
+  def post_clone_issue(current_user, issue, target_project)
+    post api("/projects/#{issue.project.id}/issues/#{issue.iid}/clone", current_user),
+      params: { to_project_id: target_project.id }
+  end
 end