ReferenceError: PointerEvent is not defined

Issue :

After upgrading to Jest 24, I get this Typescript error:

ReferenceError: PointerEvent is not defined

I use a tsconfig.spec.json (which seems to be loaded by ts-jest) which contains "lib": ["es2017", "dom"] in compilerOptions.

Expected behavior :

I expect PointerEvent to be defined, as it is part of the TypeScript dom lib.

[wtho]

I realized, this is not in jest’s hands. Jest uses JSDOM to run the tests, and after a quick check I saw there is already an issue opened in JSDOM to implement PointerEvent.

Basically the Constructor is missing: window.PointerEvent.

I suggest everyone interested in this to subscribe to this issue or even provide a PR to JSDOM: https://github.com/jsdom/jsdom/issues/2527

Once this is implemented in jsdom, it might take some additional time for jest to provide the test environment.

Until then this patching can be used:

// setupEvents.js
window.PointerEvent = function(type, eventInitDict) {}
window.BeforeUnloadEvent = function() {}

It has to be registered in jest.config.js

module.exports = {
  setupFilesAfterEnv: ['./setupEvents']
}

@ahnpnl I think this issue can be closed, there is nothing ts-jest can do about it.

[wtho]

Summarizing the discussion in https://github.com/thymikee/jest-preset-angular/issues/245:

• Combination of Method Decorator and PointerEvent in the method signature will throw this error
• Angular is not required to trigger the error
• tsconfig.spec.json is configured with "types": ["dom"]
• Other DOM-types like other events do not throw an error
• any Decorator could be used
• IDE (VSCode with TS) does not throw error

Minimal reproduction:

export function Decorator() {
  return (...args) => {};
}

class Test {
  @Decorator()
  decoratedMethodWithPointerEventType(event: PointerEvent) { }
}

describe('DOM PointerEvent and Decorators', () => {
  it('should not throw when combining a decorator with the DOM type PointerEvent', () => {
    const t = new Test()
    expect(t).toBeTruthy()
  });
})