Metrics/ClassLength is double reporting on class with singleton class

[pbstriker38]

When a class uses class << self to define class methods, rubocop reports an offense on both the class << self and the parent class.

---

Expected behavior

let(:cop_config) { { 'Max' => 5, 'CountComments' => false } }

it 'rejects a class with more than 5 lines including its singleton class' do
  expect_offense(<<~RUBY)
    class Test
    ^^^^^^^^^^ Class has too many lines. [8/5]
      class << self
        a = 1
        a = 2
        a = 3
        a = 4
        a = 5
        a = 6
      end
    end
  RUBY
end

Actual behavior

let(:cop_config) { { 'Max' => 5, 'CountComments' => false } }

it 'rejects a class with more than 5 lines including its singleton class' do
  expect_offense(<<~RUBY)
    class Test
    ^^^^^^^^^^ Class has too many lines. [8/5]
      class << self
      ^^^^^^^^^^^^^ Class has too many lines. [6/5]
        a = 1
        a = 2
        a = 3
        a = 4
        a = 5
        a = 6
      end
    end
  RUBY
end

RuboCop version

$ bundle exec rubocop -V
1.57.1 (using Parser 3.2.2.4, rubocop-ast 1.29.0, running on ruby 3.2.1) [arm64-darwin21]
  - rubocop-performance 1.19.1
  - rubocop-rspec 2.24.1

[pbstriker38]

This is where the behavior changed

45174dc

[pbstriker38]

rubocop v1.56 behaves like this

let(:cop_config) { { 'Max' => 5, 'CountComments' => false } }

it 'rejects a class with more than 5 lines including its singleton class' do
  expect_offense(<<~RUBY)
    class Test
      class << self
      ^^^^^^^^^^^^^ Class has too many lines. [6/5]
        a = 1
        a = 2
        a = 3
        a = 4
        a = 5
        a = 6
      end
    end
  RUBY
end