message: keep play button disabled if the test is empty
diff: @@ -17,6 +17,7 @@ export default class ToolBar extends React.Component {
  render() {
  const isPlayingSuite = PlaybackState.isPlaying && PlaybackState.currentRunningSuite;
  const isPlayingTest = PlaybackState.isPlaying && PlaybackState.currentRunningTest && !PlaybackState.currentRunningSuite;
  + const isTestEmpty = UiState.selectedTest.test && !UiState.selectedTest.test.commands.length;
  return (
  <div className="toolbar">
  <PlayAll
  @@ -26,7 +27,7 @@ export default class ToolBar extends React.Component {
  />
  <PlayCurrent
  isActive={!PlaybackState.paused && isPlayingTest}
  - disabled={!UiState.selectedTest.test || isPlayingSuite}
  + disabled={isTestEmpty || isPlayingSuite}
  onClick={!PlaybackState.paused ? PlaybackState.startPlaying : PlaybackState.resume}
  />
  { PlaybackState.isPlaying ? <Stop onClick={PlaybackState.abortPlaying} /> : null }
  