Testing lifecycle of layer that performs async computation

[cneumann]

Hello,
I have a (few) custom CompositeLayers that compute values from their data prop and pass those values to their sub layers for rendering. The computation can take a little time, so it happens asynchronously and when it completes the composite layers internal state is updated.

updateState({props, oldProps}) {
  if (props.data !== oldProps.data) {
     // compute new derived data, store in local state when done
     computeDerivedData(props.data).then((derivedData) => this.setState({derivedData: derivedData});
  }
}

renderLayers() {
  return [
    new SomeLayer(this.getSubLayerProps({
        // use derived data from local state
        data: this.state.derivedData
      })
    )
  ]
}

This all works fine, but now I want to write (lifecycle) tests for these layers and I'm not sure how to best do this.

If I use testLayer (from @deck.gl/test-utils) the problem is that by the time onAfterUpdate is called the async computation is not finished and I cannot make assertions about the new state yet.

I also tried using testLayerAsync but that appears to hang indefinitely and after a quick look at its implementation I believe it is because it is targeted at layers that take a url as their data prop and perform data loading internally (because here it checks layer.isLoaded).

I think a variation of testLayerAsync that supports a callback layerReady which can return true once the layer has finished all async operations and is used in place of the layer.isLoaded check in the above while loop could solve my problem, but perhaps there is another way that I'm missing?

[Pessimistress]

Just implement your own isLoaded:

get isLoaded() {
  // return asyncComputationCompleted;
}

[cneumann]

Thanks for the suggestion, trying it quickly it seems to solve my problem 😄