How do I assert on a command with no output?

[mojavelinux]

The command I'm testing doesn't output anything when it competes successfully. When I run the command with Kapok under this circumstance, Kapok hangs indefinitely waiting for output.

it('should run successfully', () => {
  return Kapok
    .start(CLI, ['generate'])
    .done()
})

What method to I use to assert no output?

I'm currently using a Promise as a workaround, but I'm not sure this is correct:

it('should run successfully', () => {
  return new Promise((resolve) => {
    Kapok
      .start(CLI, ['generate'])
      .on('exit', () => resolve())
  }).then(() => {
    // assert files were created
  })
})