Fix errors in GraphQL TodosQuery

Fixes missing target types in `TargetTypeEnum` and separates the
EE-specific types.

Adds `calls_gitaly` for the `TodoType#body` field, as an error is raised
when requesting the `todo.body field` for a `Commit` `Todo`:

    RuntimeError (Gitaly is called for field 'body' on Types::TodoType
    - please either specify a constant complexity or add
    `calls_gitaly: true` to the field declaration)

When the `Todo` (a polymorphic model) has a `target_type` of `Commit`,
requesting the `body` field calls Gitaly (`Todo#body` calls
`Todo#target` which fetches the `Commit` from Gitaly) and we get the
above error.

I've set `calls_gitaly: true` for the `TodoType#body` field (affecting
all Todos, regardless of the `target_type`) in order to avoid the error,
while we work out a better solution.

https://gitlab.com/gitlab-org/gitlab/issues/34757
https://gitlab.com/gitlab-org/gitlab/issues/34757#note_234752665

app/graphql/types/todo_target_enum.rb

@@ -2,8 +2,10 @@
 
 module Types
   class TodoTargetEnum < BaseEnum
-    value 'Issue'
-    value 'MergeRequest'
-    value 'Epic'
+    value 'COMMIT', value: 'Commit', description: 'A Commit'
+    value 'ISSUE', value: 'Issue', description: 'An Issue'
+    value 'MERGEREQUEST', value: 'MergeRequest', description: 'A MergeRequest'
   end
 end
+
+Types::TodoTargetEnum.prepend_if_ee('::EE::Types::TodoTargetEnum')

app/graphql/types/todo_type.rb

@@ -40,7 +40,8 @@ module Types
 
     field :body, GraphQL::STRING_TYPE,
           description: 'Body of the todo',
-          null: false
+          null: false,
+          calls_gitaly: true # TODO This is only true when `target_type` is `Commit`. See https://gitlab.com/gitlab-org/gitlab/issues/34757#note_234752665
 
     field :state, Types::TodoStateEnum,
           description: 'State of the todo',

changelogs/unreleased/34757-bugfix-graphql-missing-todo-types.yml

+---
+title: Fix errors in GraphQL Todos API due to missing TargetTypeEnum values
+merge_request: 19052
+author:
+type: fixed

ee/app/graphql/ee/types/todo_target_enum.rb

+# frozen_string_literal: true
+
+module EE
+  module Types
+    module TodoTargetEnum
+      extend ActiveSupport::Concern
+
+      prepended do
+        value 'DESIGN', value: 'DesignManagement::Design', description: 'A Design'
+        value 'EPIC', value: 'Epic', description: 'An Epic'
+      end
+    end
+  end
+end

ee/spec/requests/api/graphql/current_user/todos_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'getting project information' do
+  include GraphqlHelpers
+
+  set(:current_user) { create(:user) }
+  set(:design_todo) { create(:todo, user: current_user, target: create(:design)) }
+  set(:epic_todo) { create(:todo, user: current_user, target: create(:epic)) }
+  let(:fields) do
+    <<~QUERY
+    nodes {
+      #{all_graphql_fields_for('todos'.classify)}
+    }
+    QUERY
+  end
+  let(:query) do
+    graphql_query_for('currentUser', {}, query_graphql_field('todos', {}, fields))
+  end
+
+  subject { graphql_data.dig('currentUser', 'todos', 'nodes') }
+
+  before do
+    post_graphql(query, current_user: current_user)
+  end
+
+  it_behaves_like 'a working graphql query'
+
+  it 'returns Todos for all target types' do
+    is_expected.to include(
+      a_hash_including('targetType' => 'DESIGN'),
+      a_hash_including('targetType' => 'EPIC')
+    )
+  end
+end

spec/requests/api/graphql/current_user/todos_query_spec.rb

@@ -13,7 +13,7 @@ describe 'Query current user todos' do
   let(:fields) do
     <<~QUERY
     nodes {
-      id
+      #{all_graphql_fields_for('todos'.classify)}
     }
     QUERY
   end
@@ -28,6 +28,8 @@ describe 'Query current user todos' do
     post_graphql(query, current_user: current_user)
   end
 
+  it_behaves_like 'a working graphql query'
+
   it 'contains the expected ids' do
     is_expected.to include(
       a_hash_including('id' => commit_todo.to_global_id.to_s),
@@ -35,4 +37,12 @@ describe 'Query current user todos' do
       a_hash_including('id' => merge_request_todo.to_global_id.to_s)
     )
   end
+
+  it 'returns Todos for all target types' do
+    is_expected.to include(
+      a_hash_including('targetType' => 'COMMIT'),
+      a_hash_including('targetType' => 'ISSUE'),
+      a_hash_including('targetType' => 'MERGEREQUEST')
+    )
+  end
 end

spec/requests/api/graphql/current_user_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'getting project information' do
+  include GraphqlHelpers
+
+  let(:query) do
+    graphql_query_for('currentUser', {}, 'name')
+  end
+
+  subject { graphql_data['currentUser'] }
+
+  before do
+    post_graphql(query, current_user: current_user)
+  end
+
+  context 'when there is a current_user' do
+    set(:current_user) { create(:user) }
+
+    it_behaves_like 'a working graphql query'
+
+    it { is_expected.to include('name' => current_user.name) }
+  end
+
+  context 'when there is no current_user' do
+    let(:current_user) { nil }
+
+    it_behaves_like 'a working graphql query'
+
+    it { is_expected.to be_nil }
+  end
+end