TypeError: Cannot read property 'setTransform' of null when using Openlayers and Jest + Enzyme

Question

Currently using the OpenLayers ExtentInteraction and when I run my tests I manage to get the error as run test with jest:

TypeError: Cannot read property 'setTransform' of null

with the following code:

import ExtentInteraction from 'ol/interaction/Extent';

new ExtentInteraction({
  // option
});

Any suggestions as it's getting late and I'm weary. Thanks in advance.

Answer 1

The issue here is that jsdom browser doesn't support canvas API so in order to fix this you can install this dev dependency jest-canvas-mock to add canvas api to jsdom window. Here is a few steps:

Install:

yarn add -D jest-canvas-mock

// or npm

npm i -D jest-canvas-mock

Add this package as your setupFiles of jest:

{
  setupFiles: ['jest-canvas-mock']
}

That's it!