block-testing.rb

class A
  def call
    foo do
      yield if block_given?
      puts "a"
    end
  end

  def foo
    yield
    puts "foo"
  end
end

class B < A
  def call
    super do
      yield if block_given?
      puts "b"
    end
  end
end

class C < B
  def call
    super do
      puts "c"
    end
  end
end

A.new.call
puts "A"

B.new.call
puts "B"

C.new.call
puts "C"

class A
  def call(&block)
    foo do
      block.call if block
      puts "a"
    end
  end

  def foo(&block)
    block.call
    puts "foo"
  end
end

class B < A
  def call(&block)
    super do
      block.call if block
      puts "b"
    end
  end
end

class C < B
  def call
    super do
      puts "c"
    end
  end
end

A.new.call
puts "A"

B.new.call
puts "B"

C.new.call
puts "C"