Here you are not performing any actions or calling any methods.

All you are doing with this message expectation is saying that for this test to pass, the message_board should receive a call of `slow_down!`

The normal flow here would be to then execute some code to see if it happened.

```ruby
it "should receive slow down from conductor" do
  message_board.should_receive(:slow_down!)
  conductor.see_danger_coming!
end
```