Expose epic_iid in issues API

doc/api/issues.md

@@ -573,6 +573,18 @@ the `weight` parameter:
 }
 ```
 
+Users on GitLab [Ultimate](https://about.gitlab.com/pricing/) will additionally see
+the `epic_iid` property:
+
+```json
+{
+   "project_id" : 4,
+   "description" : "Omnis vero earum sunt corporis dolor et placeat.",
+   "epic_iid" : 42,
+   ...
+}
+```
+
 **Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
 
 **Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.

ee/changelogs/unreleased/winh-issue-get-epic_iid-ee.yml

+---
+title: Expose epic_iid in issues API
+merge_request: 15998
+author:
+type: added

ee/lib/ee/api/entities.rb

@@ -122,6 +122,17 @@ module EE
         end
       end
 
+      module Issue
+        extend ActiveSupport::Concern
+
+        prepended do
+          expose :epic_iid,
+                 if: -> (issue, options) { ::Ability.allowed?(options[:current_user], :read_epic, issue.project&.group) } do |issue|
+            issue.epic&.iid
+          end
+        end
+      end
+
       module MergeRequestBasic
         extend ActiveSupport::Concern
 
@@ -194,9 +205,11 @@ module EE
         extend ActiveSupport::Concern
 
         def todo_target_class(target_type)
-          ::EE::API::Entities.const_get(target_type, false)
-        rescue NameError
           super
+        rescue NameError
+          # false as second argument prevents looking up in module hierarchy
+          # see also https://gitlab.com/gitlab-org/gitlab-ce/issues/59719
+          ::EE::API::Entities.const_get(target_type, false)
         end
       end
 

ee/spec/fixtures/api/schemas/public_api/v4/issues.json

@@ -4,7 +4,8 @@
     { "$ref": "../../../../../../../spec/fixtures/api/schemas/public_api/v4/issues.json" },
     {
       "properties": {
-        "weight": { "type": ["integer", "null"] }
+        "weight": { "type": ["integer", "null"] },
+        "epic_iid": { "type": ["integer", "null"] }
       }
     }
   ]

ee/spec/requests/api/issues_spec.rb

@@ -5,6 +5,9 @@ describe API::Issues, :mailer do
   set(:project) do
     create(:project, :public, creator_id: user.id, namespace: user.namespace)
   end
+  set(:group) { create(:group) }
+  set(:epic) { create(:epic, group: group) }
+  set(:group_project) { create(:project, :public, creator_id: user.id, namespace: group) }
 
   let(:user2)       { create(:user) }
   set(:author)      { create(:author) }
@@ -28,6 +31,34 @@ describe API::Issues, :mailer do
     project.add_reporter(user)
   end
 
+  shared_examples 'exposes epic_iid' do
+    context 'with epics feature' do
+      before do
+        stub_licensed_features(epics: true)
+      end
+
+      it 'contains epic_iid in response' do
+        subject
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(epic_issue_response_for(epic_issue)['epic_iid']).to eq(epic.iid)
+      end
+    end
+
+    context 'without epics feature' do
+      before do
+        stub_licensed_features(epics: false)
+      end
+
+      it 'does not contain epic_iid in response' do
+        subject
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(epic_issue_response_for(epic_issue)).not_to have_key('epic_iid')
+      end
+    end
+  end
+
   describe "GET /issues" do
     context "when authenticated" do
       it 'matches V4 response schema' do
@@ -77,8 +108,7 @@ describe API::Issues, :mailer do
   end
 
   describe 'GET /groups/:id/issues' do
-    let!(:group)            { create(:group) }
-    let!(:group_project)    { create(:project, :public, creator_id: user.id, namespace: group) }
+    subject { get api("/groups/#{group.id}/issues", user) }
 
     context 'filtering by assignee_username' do
       let(:another_assignee) { create(:assignee) }
@@ -86,29 +116,93 @@ describe API::Issues, :mailer do
       let!(:issue2) { create(:issue, author: user2, project: group_project, weight: 5, created_at: 2.days.ago) }
       let!(:issue3) { create(:issue, author: user2, assignees: [assignee, another_assignee], project: group_project, weight: 3, created_at: 1.day.ago) }
 
-      it 'returns issues with multiple assignees' do
+      subject do
         get api("/groups/#{group.id}/issues", user),
-             params: { assignee_username: [assignee.username, another_assignee.username], scope: 'all' }
+            params: { assignee_username: [assignee.username, another_assignee.username], scope: 'all' }
+      end
+
+      it 'returns issues with multiple assignees' do
+        subject
 
         expect_paginated_array_response(issue3.id)
       end
     end
+
+    include_examples 'exposes epic_iid' do
+      let!(:epic_issue) { create(:issue, project: group_project, epic: epic) }
+    end
   end
 
   describe "GET /projects/:id/issues" do
+    subject { get api("/projects/#{project.id}/issues", user) }
+
     context 'filtering by assignee_username' do
       let(:another_assignee) { create(:assignee) }
       let!(:issue1) { create(:issue, author: user2, project: project, weight: 1, created_at: 3.days.ago) }
       let!(:issue2) { create(:issue, author: user2, project: project, weight: 5, created_at: 2.days.ago) }
       let!(:issue3) { create(:issue, author: user2, assignees: [assignee, another_assignee], project: project, weight: 3, created_at: 1.day.ago) }
 
-      it 'returns issues with multiple assignees' do
+      subject do
         get api("/projects/#{project.id}/issues", user),
-             params: { assignee_username: [assignee.username, another_assignee.username], scope: 'all' }
+            params: { assignee_username: [assignee.username, another_assignee.username], scope: 'all' }
+      end
+
+      it 'returns issues with multiple assignees' do
+        subject
 
         expect_paginated_array_response(issue3.id)
       end
     end
+
+    context 'on personal project' do
+      let!(:epic_issue) { create(:issue, project: project, epic: epic) }
+
+      before do
+        stub_licensed_features(epics: true)
+      end
+
+      it 'does not contain epic_iid in response' do
+        subject
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(epic_issue_response_for(epic_issue)).not_to have_key('epic_iid')
+      end
+    end
+
+    context 'on group project' do
+      let!(:epic_issue) { create(:issue, project: group_project, epic: epic) }
+
+      subject { get api("/projects/#{group_project.id}/issues", user) }
+
+      include_examples 'exposes epic_iid'
+    end
+  end
+
+  describe 'GET /project/:id/issues/:issue_id' do
+    context 'on personal project' do
+      let!(:epic_issue) { create(:issue, project: project, epic: epic) }
+
+      subject { get api("/projects/#{project.id}/issues/#{epic_issue.iid}", user) }
+
+      before do
+        stub_licensed_features(epics: true)
+      end
+
+      it 'does not contain epic_iid in response' do
+        subject
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(epic_issue_response_for(epic_issue)).not_to have_key('epic_iid')
+      end
+    end
+
+    context 'on group project' do
+      let!(:epic_issue) { create(:issue, project: group_project, epic: epic) }
+
+      subject { get api("/projects/#{group_project.id}/issues/#{epic_issue.iid}", user) }
+
+      include_examples 'exposes epic_iid'
+    end
   end
 
   describe "POST /projects/:id/issues" do
@@ -174,4 +268,10 @@ describe API::Issues, :mailer do
       end
     end
   end
+
+  private
+
+  def epic_issue_response_for(epic_issue)
+    Array.wrap(json_response).find { |issue| issue['id'] == epic_issue.id }
+  end
 end

lib/api/entities.rb

@@ -978,7 +978,9 @@ module API
       expose :created_at
 
       def todo_target_class(target_type)
-        ::API::Entities.const_get(target_type)
+        # false as second argument prevents looking up in module hierarchy
+        # see also https://gitlab.com/gitlab-org/gitlab-ce/issues/59719
+        ::API::Entities.const_get(target_type, false)
       end
     end
 
@@ -1731,6 +1733,7 @@ API::Entities.prepend_if_ee('EE::API::Entities::Entities')
 ::API::Entities::Group.prepend_if_ee('EE::API::Entities::Group', with_descendants: true)
 ::API::Entities::GroupDetail.prepend_if_ee('EE::API::Entities::GroupDetail')
 ::API::Entities::IssueBasic.prepend_if_ee('EE::API::Entities::IssueBasic', with_descendants: true)
+::API::Entities::Issue.prepend_if_ee('EE::API::Entities::Issue')
 ::API::Entities::List.prepend_if_ee('EE::API::Entities::List')
 ::API::Entities::MergeRequestBasic.prepend_if_ee('EE::API::Entities::MergeRequestBasic', with_descendants: true)
 ::API::Entities::Namespace.prepend_if_ee('EE::API::Entities::Namespace')