auto.rb

my_pilot = PryAutopilot.new do
  on ->(frame) { frame.eval("@i == x") } do
    puts "fizz (@i == x) x is #{frame.var("x")}"
  end

  on ->(frame) { frame.eval("@i == y") } do
    puts "buzz (@i == y) y is #{frame.var("y")}"
  end

  on ->(frame) { frame.eval("@i == (y + x)") } do
    puts "fizzbuzz (@i == (x + y)), (x + y) is #{frame.eval("x+y")}"
    run "exit-all"
  end

  on ->(frame) { true } do
    run "step"
  end
end

Pry.config.input = my_pilot

def fizzbuzz(x, y)
  binding.pry
  @i = 0
  1.upto(100) { |i| @i = i }
end

fizzbuzz(3, 5)

OUTPUT

fizz (@i == x) x is 3
buzz (@i == y) y is 5
fizzbuzz (@i == (x + y)), (x + y) is 8

  on ->(frame) { @i == y + x) } do
    frame.exec {puts "fizzbuzz (@i == (x + y)), (x + y) is #{x+y}"}    
    run "exit-all"
  end