Add GraphQL mutation to promote an issue to an epic

Expose prmoting issue to an epic through a GraphQL mutation

doc/api/graphql/reference/gitlab_schema.graphql

@@ -13300,6 +13300,7 @@ type Mutation {
   prometheusIntegrationCreate(input: PrometheusIntegrationCreateInput!): PrometheusIntegrationCreatePayload
   prometheusIntegrationResetToken(input: PrometheusIntegrationResetTokenInput!): PrometheusIntegrationResetTokenPayload
   prometheusIntegrationUpdate(input: PrometheusIntegrationUpdateInput!): PrometheusIntegrationUpdatePayload
+  promoteToEpic(input: PromoteToEpicInput!): PromoteToEpicPayload
   removeAwardEmoji(input: RemoveAwardEmojiInput!): RemoveAwardEmojiPayload @deprecated(reason: "Use awardEmojiRemove. Deprecated in 13.2")
   removeProjectFromSecurityDashboard(input: RemoveProjectFromSecurityDashboardInput!): RemoveProjectFromSecurityDashboardPayload
 
@@ -16758,6 +16759,56 @@ Identifier of PrometheusService
 """
 scalar PrometheusServiceID
 
+"""
+Autogenerated input type of PromoteToEpic
+"""
+input PromoteToEpicInput {
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  The group the promoted epic will belong to
+  """
+  groupPath: ID
+
+  """
+  The IID of the issue to mutate
+  """
+  iid: String!
+
+  """
+  The project the issue to mutate is in
+  """
+  projectPath: ID!
+}
+
+"""
+Autogenerated return type of PromoteToEpic
+"""
+type PromoteToEpicPayload {
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  The epic after issue promotion
+  """
+  epic: Epic
+
+  """
+  Errors encountered during execution of the mutation.
+  """
+  errors: [String!]!
+
+  """
+  The issue after mutation
+  """
+  issue: Issue
+}
+
 type Query {
   """
   Get information about current user

doc/api/graphql/reference/gitlab_schema.json

@@ -38628,6 +38628,33 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "promoteToEpic",
+              "description": null,
+              "args": [
+                {
+                  "name": "input",
+                  "description": null,
+                  "type": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "INPUT_OBJECT",
+                      "name": "PromoteToEpicInput",
+                      "ofType": null
+                    }
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "PromoteToEpicPayload",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "removeAwardEmoji",
               "description": null,
@@ -48712,6 +48739,146 @@
           "enumValues": null,
           "possibleTypes": null
         },
+        {
+          "kind": "INPUT_OBJECT",
+          "name": "PromoteToEpicInput",
+          "description": "Autogenerated input type of PromoteToEpic",
+          "fields": null,
+          "inputFields": [
+            {
+              "name": "projectPath",
+              "description": "The project the issue to mutate is in",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "ID",
+                  "ofType": null
+                }
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "iid",
+              "description": "The IID of the issue to mutate",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "String",
+                  "ofType": null
+                }
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "groupPath",
+              "description": "The group the promoted epic will belong to",
+              "type": {
+                "kind": "SCALAR",
+                "name": "ID",
+                "ofType": null
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "clientMutationId",
+              "description": "A unique identifier for the client performing the mutation.",
+              "type": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              },
+              "defaultValue": null
+            }
+          ],
+          "interfaces": null,
+          "enumValues": null,
+          "possibleTypes": null
+        },
+        {
+          "kind": "OBJECT",
+          "name": "PromoteToEpicPayload",
+          "description": "Autogenerated return type of PromoteToEpic",
+          "fields": [
+            {
+              "name": "clientMutationId",
+              "description": "A unique identifier for the client performing the mutation.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "epic",
+              "description": "The epic after issue promotion",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "Epic",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "errors",
+              "description": "Errors encountered during execution of the mutation.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "LIST",
+                  "name": null,
+                  "ofType": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "SCALAR",
+                      "name": "String",
+                      "ofType": null
+                    }
+                  }
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "issue",
+              "description": "The issue after mutation",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "Issue",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
         {
           "kind": "OBJECT",
           "name": "Query",

doc/api/graphql/reference/index.md

@@ -2407,6 +2407,17 @@ Autogenerated return type of PrometheusIntegrationUpdate.
 | `errors` | String! => Array | Errors encountered during execution of the mutation. |
 | `integration` | AlertManagementPrometheusIntegration | The newly created integration |
 
+### PromoteToEpicPayload
+
+Autogenerated return type of PromoteToEpic.
+
+| Field | Type | Description |
+| ----- | ---- | ----------- |
+| `clientMutationId` | String | A unique identifier for the client performing the mutation. |
+| `epic` | Epic | The epic after issue promotion |
+| `errors` | String! => Array | Errors encountered during execution of the mutation. |
+| `issue` | Issue | The issue after mutation |
+
 ### Release
 
 Represents a release.

ee/app/graphql/ee/types/mutation_type.rb

@@ -13,6 +13,7 @@ module MutationType
         mount_mutation ::Mutations::Issues::SetIteration
         mount_mutation ::Mutations::Issues::SetWeight
         mount_mutation ::Mutations::Issues::SetEpic
+        mount_mutation ::Mutations::Issues::PromoteToEpic
         mount_mutation ::Mutations::Environments::CanaryIngress::Update
         mount_mutation ::Mutations::EpicTree::Reorder
         mount_mutation ::Mutations::Epics::Update

ee/app/graphql/mutations/issues/promote_to_epic.rb

+# frozen_string_literal: true
+
+module Mutations
+  module Issues
+    class PromoteToEpic < Base
+      include Mutations::ResolvesGroup
+
+      graphql_name 'PromoteToEpic'
+
+      argument :group_path, GraphQL::ID_TYPE,
+               required: false,
+               description: 'The group the promoted epic will belong to'
+
+      field :epic,
+            Types::EpicType,
+            null: true,
+            description: "The epic after issue promotion"
+
+      def resolve(project_path:, iid:, group_path: nil)
+        errors = []
+        issue = authorized_find!(project_path: project_path, iid: iid)
+        project = issue.project
+        group = get_group_by_path!(group_path)
+
+        begin
+          epic = ::Epics::IssuePromoteService.new(project, current_user).execute(issue, group)
+        rescue => error
+          errors << error.message
+        end
+
+        errors << issue&.errors&.full_messages
+        errors << epic&.errors&.full_messages
+
+        {
+          issue: issue,
+          epic: epic,
+          errors: errors.compact.flatten
+        }
+      end
+
+      private
+
+      def get_group_by_path!(group_path)
+        return unless group_path
+
+        group = resolve_group(full_path: group_path).try(:sync)
+        raise raise_resource_not_available_error! unless group
+
+        group
+      end
+    end
+  end
+end

ee/changelogs/unreleased/233974-promote-issue-to-epic.yml

+---
+title: Add GraphQL mutation to promote an issue to an epic
+merge_request: 46143
+author:
+type: added

ee/spec/graphql/mutations/issues/promote_to_epic_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+RSpec.describe Mutations::Issues::PromoteToEpic do
+  let(:new_epic_group) { nil }
+
+  let_it_be(:group) { create(:group) }
+  let_it_be(:project) { create(:project, group: group) }
+  let_it_be(:issue) { create(:issue, project: project) }
+  let_it_be(:user) { create(:user) }
+
+  before do
+    stub_licensed_features(epics: true)
+  end
+
+  subject(:mutation) { described_class.new(object: nil, context: { current_user: user }, field: nil) }
+
+  RSpec.shared_examples 'successfully promotes issue to epic' do
+    it 'returns the issue and the epic', :aggregate_failures do
+      expect(mutated_issue).to eq(issue)
+      expect(mutated_issue.state).to eq('closed')
+      expect(issue.reload.promoted_to_epic_id).to eq(epic.id)
+      expect(epic).not_to be_nil
+      expect(epic.title).to eq(issue.title)
+      expect(epic.group).to eq(epic_group)
+      expect(subject[:errors]).to be_empty
+    end
+  end
+
+  describe '#resolve' do
+    let(:mutated_issue) { subject[:issue] }
+    let(:epic) { subject[:epic] }
+
+    subject { mutation.resolve(project_path: issue.project.full_path, iid: issue.iid, group_path: new_epic_group&.full_path) }
+
+    it 'raises an error if the resource is not accessible to the user' do
+      expect { subject }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+    end
+
+    context 'when issue is accessible to the user' do
+      before do
+        project.add_developer(user)
+      end
+
+      context 'when the user cannot promote the issue' do
+        it 'returns the issue and the errors', :aggregate_failures do
+          expect(mutated_issue).to eq(issue)
+          expect(epic).to be_nil
+          expect(subject[:errors]).to eq(['Cannot promote issue due to insufficient permissions.'])
+        end
+      end
+
+      context 'when the user can promote the issue' do
+        before do
+          group.add_reporter(user)
+        end
+
+        it_behaves_like 'successfully promotes issue to epic' do
+          let(:epic_group) { group }
+        end
+
+        context 'when destination group does not exist' do
+          let(:new_epic_group) { double('group', full_path: 'non-existing') }
+          let(:user) { create(:user, :admin) }
+
+          it 'raises an error if the resource is not accessible to the user' do
+            expect { subject }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+          end
+        end
+      end
+    end
+  end
+end

ee/spec/requests/api/graphql/mutations/issues/promote_to_epic_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Setting the epic of an issue' do
+  include GraphqlHelpers
+
+  let(:new_epic_group) { nil }
+
+  let_it_be(:current_user) { create(:user) }
+  let_it_be(:group) { create(:group) }
+  let_it_be(:project) { create(:project, group: group) }
+  let_it_be(:issue) { create(:issue, project: project) }
+  let_it_be(:user) { create(:user) }
+  let(:input) { { group_path: new_epic_group&.full_path } }
+
+  let(:mutation) do
+    graphql_mutation(
+      :promote_to_epic,
+      { project_path: project.full_path, iid: issue.iid.to_s }.merge(input),
+      <<~GRAPHQL
+        clientMutationId
+        errors
+        issue {
+          iid
+          title
+          state
+        }
+        epic {
+          id
+          title
+          group {
+            id
+          }
+        }
+    GRAPHQL
+    )
+  end
+
+  def mutation_response
+    graphql_mutation_response(:promote_to_epic)
+  end
+
+  before_all do
+    project.add_developer(current_user)
+    group.add_developer(current_user)
+  end
+
+  before do
+    stub_licensed_features(epics: true)
+  end
+
+  it 'returns an error if the user is not allowed to update the issue' do
+    error = "The resource that you are attempting to access does not exist or you "\
+            "don't have permission to perform this action"
+
+    post_graphql_mutation(mutation, current_user: create(:user))
+
+    expect(graphql_errors).to include(a_hash_including('message' => error))
+  end
+
+  it 'returns an error if issue can not be updated' do
+    issue.update_column(:author_id, nil)
+    post_graphql_mutation(mutation, current_user: current_user)
+
+    expect(mutation_response["errors"]).to eq(["Author can't be blank"])
+  end
+
+  it 'promotes the issue to epic' do
+    post_graphql_mutation(mutation, current_user: current_user)
+
+    expect(response).to have_gitlab_http_status(:success)
+    expect(mutation_response['errors']).to be_empty
+    expect(mutation_response['issue']['state']).to eq('closed')
+    expect(mutation_response['epic']['title']).to eq(issue.title)
+    expect(mutation_response['epic']['group']['id']).to eq(group.to_global_id.to_s)
+    expect(issue.reload.promoted_to_epic_id.to_s).to eq(GlobalID.parse(mutation_response['epic']['id']).model_id)
+  end
+
+  context 'when epic has to be in a different group' do
+    let(:new_epic_group) { create(:group) }
+
+    context 'when user cannot create epic in new group' do
+      it 'does not promote the issue to epic' do
+        post_graphql_mutation(mutation, current_user: current_user)
+
+        expect(mutation_response['issue']['state']).to eq('opened')
+        expect(mutation_response['errors']).not_to be_empty
+        expect(mutation_response['errors']).to eq(['Cannot promote issue due to insufficient permissions.'])
+      end
+    end
+
+    context 'when user can create epic in new group' do
+      before do
+        new_epic_group.add_developer(current_user)
+      end
+
+      it 'promotes the issue to epic' do
+        post_graphql_mutation(mutation, current_user: current_user)
+
+        expect(response).to have_gitlab_http_status(:success)
+        expect(mutation_response['errors']).to be_empty
+        expect(mutation_response['issue']['state']).to eq('closed')
+        expect(mutation_response['epic']['title']).to eq(issue.title)
+        expect(mutation_response['epic']['group']['id']).to eq(new_epic_group.to_global_id.to_s)
+        expect(issue.reload.promoted_to_epic_id.to_s).to eq(GlobalID.parse(mutation_response['epic']['id']).model_id)
+      end
+    end
+  end
+end