Jest: TypeError: Cannot redefine property: window

Question

When I run jest tests locally with yarn test:unit:watch, I am getting this error from the jest library:

Test suite failed to run

TypeError: Cannot redefine property: window

at Object.<anonymous> (node_modules/jest-canvas-mock/lib/index.js:11:17)

Any suggestion what's wrong? I tried to delete node_modules and reinstall and also to clone the repo again but it's repeating. Others are not facing this problem.

I got such an error in our own testing codebase, and was able to fix it by creating a mock implementation following this answer: stackoverflow.com/a/56999581 — marcw
– marcw, Commented Apr 21, 2023 at 7:03

dhilt · Accepted Answer · 2023-04-21 16:22:19Z

17

In addition to mockImplementation approach mentioned by @marcw (link) and since I used Object.create approach from the same thread (link), I was able to solve the issue by changing

global.window = Object.create(window);

to

global.window ??= Object.create(window);

answered Apr 21, 2023 at 16:22

dhilt

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Comments

sklnd · Accepted Answer · 2023-04-19 22:55:40Z

10

This was an issue in jest-canvas-mock that was fixed in 2.4.0.

Upgrading to 2.4.0 or later should resolve the issue, and allow use of node 18 or better.

answered Apr 19, 2023 at 22:55

sklnd

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2 Comments

ffritz Over a year ago

I can not confirm this. Got 2.4.0 and it is still an issue.

rob Over a year ago

I added npm install jest-canvas-mock@latest --legacy-peer-deps to my CI pipeline and that did fix it.

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