How modules are added to the inheritance chain in Ruby

klass.rb

module ModuleA
  def method
    puts "method called from ModuleA"
  end
end

module ModuleB
  def method
    puts "method called from ModuleB"
    super
  end
end

class Parent
  include ModuleA
  
  def method
    puts "method called from Parent"
    super
  end
end

class Child < Parent
  include ModuleB
  
  def method
    puts "method called from Child"
    super
  end
end

Child.new.method

#=> method called from Child
#=> method called from ModuleB
#=> method called from Parent
#=> method called from ModuleA

puts ModuleA.ancestors.inspect
puts ModuleB.ancestors.inspect
puts Parent.ancestors.inspect
puts Child.ancestors.inspect

#=> [ModuleA]
#=> [ModuleB]
#=> [Parent, ModuleA, Object, Kernel]
#=> [Child, ModuleB, Parent, ModuleA, Object, Kernel]

Child.ancestors.each do |ancestor|
  puts ancestor.ancestors.inspect
end

#=> [Child, ModuleB, Parent, ModuleA, Object, Kernel]
#=> [ModuleB]
#=> [Parent, ModuleA, Object, Kernel]
#=> [ModuleA]
#=> [Object, Kernel]
#=> [Kernel]