[Bug]: structuredClone under jest fails instanceof check

[guydunton]

Version

29.7.0

Steps to reproduce

1. Clone https:/guydunton/jest-structured-clone-issue
2. Run npm run test

Expected behavior

I would expect the following test to pass:

test('structuredClone', () => {
  const origDate = new Date();
  const copyDate = structuredClone(origDate);

  const isOrigDate = origDate instanceof Date; // true
  const isCopyDate = copyDate instanceof Date; // false?

  expect(isCopyDate).toBe(isOrigDate);
});

Actual behavior

instanceof returns different values for a value & it's clone (using structuredClone) causing the test to fail.

  ● structuredClone

    expect(received).toBe(expected) // Object.is equality

    Expected: true
    Received: false

       6 |   const isCopyDate = copyDate instanceof Date;
       7 |
    >  8 |   expect(isCopyDate).toBe(isOrigDate);
         |                      ^
       9 | });
      10 |

      at Object.toBe (main.test.js:8:22)

Additional context

Running the following code in Node (20.11.1) gives the expected result:

const origDate = new Date();
const cloneDate = structuredClone(origDate);
console.log('origDate', origDate instanceof Date);      // true
console.log('cloneDate', cloneDate instanceof Date);    // true

Environment

System:
    OS: macOS 14.3.1
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 20.11.1 - ~/.nvm/versions/node/v20.11.1/bin/node
    Yarn: 1.22.21 - /usr/local/bin/yarn
    npm: 10.2.4 - ~/.nvm/versions/node/v20.11.1/bin/npm
  npmPackages:
    jest: ^29.7.0 => 29.7.0

[mrazauskas]

Somewhat similar to #14011

Looks like the root of the problem is #2549. Try using jest-light-runner. Reference: #2549 (comment)

[guydunton]

Somewhat similar to #14011

Looks like the root of the problem is #2549. Try using jest-light-runner. Reference: #2549 (comment)

Ah that solves it! Thank you!

It would be nice to not need to install a different runner but at least I have a way forwards

[mrazauskas]

It would be nice to not need to install a different runner but at least I have a way forwards

Indeed that would be nice. To make this work Jest should give up isolating tests (unlikely) or a limitation on Node.js side should be fixed (follow nodejs/node#31852).

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