Forwardport from ruby/ruby

 * ruby/ruby@cacdf26 * ruby/ruby@67e062b

Author: hsbt

test/matrix/test_matrix.rb

@@ -820,13 +820,15 @@ def test_adjoint
  end
 
  def test_ractor
- obj1 = @m1.freeze
+ assert_ractor(<<~RUBY, require: 'matrix')
+ obj1 = Matrix[[1, 2], [3, 4]].freeze
 
- obj2 = Ractor.new obj1 do |obj|
- obj
- end.take
- assert_same obj1, obj2
- end if defined?(Ractor)
+ obj2 = Ractor.new obj1 do |obj|
+ obj
+ end.take
+ assert_same obj1, obj2
+ RUBY
+ end
 
  def test_rotate_with_symbol
  assert_equal(Matrix[[4, 1], [5, 2], [6, 3]], @m1.rotate_entries)