I am writing tests using Jest for components that use canvas elements. I keep getting an error when I run my tests that looks like this.
Error: Not implemented: HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)
From my understanding Jest uses jsdom for its testing and that jsdom is compatible with canvas if you install the canvas or canvas-prebuilt packages.
I have tried installing each of these packages and neither of them have resolved the error. The only thing that I think could be going wrong is that jsdom cannot find the canvas or canvas-prebuilt packages. Does anyone know a way to fix this error or test to see if jsdom is finding the other packages? Thanks a lot!
My team is using create-react-app
and we had previously addressed this problem by adding the npm package jest-canvas-mock
. Now after upgrading to react-scripts 3.4.1, we also had to add a specific import to our src/setupTests.ts
file:
import 'jest-canvas-mock';
You can create your own mock of the function in a jest setup script
HTMLCanvasElement.prototype.getContext = () => { // return whatever getContext has to return };
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