busted example with global functions

t_spec.lua

function processEvent(e)
  eventId = getEventType(e)
  if eventId == 3 then
    return 3
  else
    return 0
  end
end

describe("processEvent", function()
  it("calls getEventType with the event", function()
	local getEventType_argument
    function getEventType(x)
      getEventType_argument = x
    end
    processEvent(42)
    assert.equal(getEventType_argument, 42)
  end)

  it("returns 3 if getEventType returns 3", function()
    function getEventType()
      return 3
    end
    assert.equal(processEvent(), 3)
  end)

  it("returns 0 if getEventType returns not 3", function()
    function getEventType()
      return 42
    end
    assert.equal(processEvent(), 0)
  end)
 end)