Add graphQL mutation for destroying issue boards

- add mutation and specs
- update the graphql documentation
- update Boards::DestroyService to use ServiceResponse

app/graphql/mutations/boards/destroy.rb

+# frozen_string_literal: true
+
+module Mutations
+  module Boards
+    class Destroy < ::Mutations::BaseMutation
+      graphql_name 'DestroyBoard'
+
+      field :board,
+            Types::BoardType,
+            null: true,
+            description: 'The board after mutation'
+      argument :id,
+                ::Types::GlobalIDType[::Board],
+                required: true,
+                description: 'The global ID of the board to destroy'
+
+      authorize :admin_board
+
+      def resolve(id:)
+        board = authorized_find!(id: id)
+
+        response = ::Boards::DestroyService.new(board.resource_parent, current_user).execute(board)
+
+        {
+          board: response.success? ? nil : board,
+          errors: response.errors
+        }
+      end
+
+      private
+
+      def find_object(id:)
+        GitlabSchema.object_from_id(id, expected_type: ::Board)
+      end
+    end
+  end
+end

app/graphql/types/mutation_type.rb

@@ -14,6 +14,7 @@ module Types
     mount_mutation Mutations::AwardEmojis::Add
     mount_mutation Mutations::AwardEmojis::Remove
     mount_mutation Mutations::AwardEmojis::Toggle
+    mount_mutation Mutations::Boards::Destroy
     mount_mutation Mutations::Boards::Issues::IssueMoveList
     mount_mutation Mutations::Boards::Lists::Create
     mount_mutation Mutations::Boards::Lists::Update

app/services/boards/destroy_service.rb

@@ -3,9 +3,13 @@
 module Boards
   class DestroyService < Boards::BaseService
     def execute(board)
-      return false if parent.boards.size == 1
+      if parent.boards.size == 1
+        return ServiceResponse.error(message: "The board could not be deleted, because the parent doesn't have any other boards.")
+      end
 
-      board.destroy
+      board.destroy!
+
+      ServiceResponse.success
     end
   end
 end

changelogs/unreleased/233455-destroy-board-graphql.yml

+---
+title: Destroy issue board via GraphQL
+merge_request: 40930
+author:
+type: added

doc/api/graphql/reference/gitlab_schema.graphql

@@ -4340,6 +4340,41 @@ enum DesignVersionEvent {
   NONE
 }
 
+"""
+Autogenerated input type of DestroyBoard
+"""
+input DestroyBoardInput {
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  The global ID of the board to destroy
+  """
+  id: BoardID!
+}
+
+"""
+Autogenerated return type of DestroyBoard
+"""
+type DestroyBoardPayload {
+  """
+  The board after mutation
+  """
+  board: Board
+
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  Errors encountered during execution of the mutation.
+  """
+  errors: [String!]!
+}
+
 """
 Autogenerated input type of DestroyNote
 """
@@ -10583,6 +10618,7 @@ type Mutation {
   designManagementDelete(input: DesignManagementDeleteInput!): DesignManagementDeletePayload
   designManagementMove(input: DesignManagementMoveInput!): DesignManagementMovePayload
   designManagementUpload(input: DesignManagementUploadInput!): DesignManagementUploadPayload
+  destroyBoard(input: DestroyBoardInput!): DestroyBoardPayload
   destroyNote(input: DestroyNoteInput!): DestroyNotePayload
   destroySnippet(input: DestroySnippetInput!): DestroySnippetPayload
 

doc/api/graphql/reference/gitlab_schema.json

@@ -11999,6 +11999,108 @@
           ],
           "possibleTypes": null
         },
+        {
+          "kind": "INPUT_OBJECT",
+          "name": "DestroyBoardInput",
+          "description": "Autogenerated input type of DestroyBoard",
+          "fields": null,
+          "inputFields": [
+            {
+              "name": "id",
+              "description": "The global ID of the board to destroy",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "BoardID",
+                  "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": "DestroyBoardPayload",
+          "description": "Autogenerated return type of DestroyBoard",
+          "fields": [
+            {
+              "name": "board",
+              "description": "The board after mutation",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "Board",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "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": "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
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
         {
           "kind": "INPUT_OBJECT",
           "name": "DestroyNoteInput",
@@ -30360,6 +30462,33 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "destroyBoard",
+              "description": null,
+              "args": [
+                {
+                  "name": "input",
+                  "description": null,
+                  "type": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "INPUT_OBJECT",
+                      "name": "DestroyBoardInput",
+                      "ofType": null
+                    }
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "DestroyBoardPayload",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "destroyNote",
               "description": null,

doc/api/graphql/reference/index.md

@@ -728,6 +728,16 @@ A specific version in which designs were added, modified or deleted
 | `id` | ID! | ID of the design version |
 | `sha` | ID! | SHA of the design version |
 
+### DestroyBoardPayload
+
+Autogenerated return type of DestroyBoard
+
+| Field | Type | Description |
+| ----- | ---- | ----------- |
+| `board` | Board | The board after mutation |
+| `clientMutationId` | String | A unique identifier for the client performing the mutation. |
+| `errors` | String! => Array | Errors encountered during execution of the mutation. |
+
 ### DestroyNotePayload
 
 Autogenerated return type of DestroyNote

ee/spec/services/boards/destroy_service_spec.rb

@@ -4,8 +4,8 @@ require 'spec_helper'
 
 RSpec.describe Boards::DestroyService do
   describe '#execute' do
-    let(:project) { create(:project) }
-    let(:group) { create(:group) }
+    let_it_be(:project) { create(:project) }
+    let_it_be(:group) { create(:group) }
 
     shared_examples 'remove the board' do |parent_name|
       let(:parent) { public_send(parent_name) }
@@ -17,13 +17,17 @@ RSpec.describe Boards::DestroyService do
         it "removes board from #{parent_name}" do
           create(:board, parent_name => parent)
 
-          expect { service.execute(board) }.to change(parent.boards, :count).by(-1)
+          expect do
+            expect(service.execute(board)).to be_success
+          end.to change(parent.boards, :count).by(-1)
         end
       end
 
       context "when #{parent_name} have one board" do
         it "does not remove board from #{parent_name}" do
-          expect { service.execute(board) }.not_to change(group.boards, :count)
+          expect do
+            expect(service.execute(board)).to be_error
+          end.not_to change(parent.boards, :count)
         end
       end
     end

spec/requests/api/graphql/mutations/boards/destroy_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Mutations::Boards::Destroy do
+  include GraphqlHelpers
+
+  let_it_be(:current_user, reload: true) { create(:user) }
+  let_it_be(:project, reload: true) { create(:project) }
+  let_it_be(:board) { create(:board, project: project) }
+  let_it_be(:other_board) { create(:board, project: project) }
+  let(:mutation) do
+    variables = {
+      id: GitlabSchema.id_from_object(board).to_s
+    }
+
+    graphql_mutation(:destroy_board, variables)
+  end
+
+  subject { post_graphql_mutation(mutation, current_user: current_user) }
+
+  def mutation_response
+    graphql_mutation_response(:destroy_board)
+  end
+
+  context 'when the user does not have permission' do
+    it_behaves_like 'a mutation that returns a top-level access error'
+
+    it 'does not destroy the board' do
+      expect { subject }.not_to change { Board.count }
+    end
+  end
+
+  context 'when the user has permission' do
+    before do
+      project.add_maintainer(current_user)
+    end
+
+    context 'when given id is not for a board' do
+      let_it_be(:board) { build_stubbed(:issue, project: project) }
+
+      it 'returns an error' do
+        subject
+
+        expect(graphql_errors.first['message']).to include('does not represent an instance of Board')
+      end
+    end
+
+    context 'when everything is ok' do
+      it 'destroys the board' do
+        expect { subject }.to change { Board.count }.from(2).to(1)
+      end
+
+      it 'returns an empty board' do
+        post_graphql_mutation(mutation, current_user: current_user)
+
+        expect(mutation_response).to have_key('board')
+        expect(mutation_response['board']).to be_nil
+      end
+    end
+
+    context 'when there is only 1 board for the parent' do
+      before do
+        other_board.destroy!
+      end
+
+      it 'does not destroy the board' do
+        expect { subject }.not_to change { Board.count }.from(1)
+      end
+
+      it 'returns an error and not nil board' do
+        subject
+
+        expect(mutation_response['errors']).not_to be_empty
+        expect(mutation_response['board']).not_to be_nil
+      end
+    end
+  end
+end