module Pry::Testable::Mockable

def mock_command(cmd, args = [], opts = {})
  output = StringIO.new
  pry = Pry.new(output: output)
  ret = cmd.new(opts.merge(pry_instance: pry, output: output)).call_safely(*args)
  Struct.new(:output, :return).new(output.string, ret)
end

def mock_exception(*mock_backtrace)
  StandardError.new.tap do |e|
    e.define_singleton_method(:backtrace) { mock_backtrace }
  end
end