Object Properties are ignored in expect when there is a Symbol.iterator

[mikearnaldi]

Describe the bug

When there is a Symbol.iterator inside an object vitest fails to check for other properties

Reproduction

The following test should fail:

import { describe, expect, it } from "vitest"

describe("Vitest Issue", () => {
  it("compares", () => {
    const a = {
      value: 0,
      [Symbol.iterator]: [0, 1, 2][Symbol.iterator]
    }
    const b = {
      value: 1,
      [Symbol.iterator]: [0, 1, 2][Symbol.iterator]
    }
    expect(a).toStrictEqual(b)
  })
})

System Info

independent from system

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[mikearnaldi]

Note that also the iterator is ignored, the following keeps passing:

import { describe, expect, it } from "vitest"

describe("Vitest Issue", () => {
  it("compares", () => {
    const a = {
      value: 0,
      [Symbol.iterator]: [0, 1, 2, Math.random()][Symbol.iterator]
    }
    const b = {
      value: 1,
      [Symbol.iterator]: [0, 1, 2, Math.random()][Symbol.iterator]
    }
    expect(a).toStrictEqual(b)
  })
})

[sheremet-va]

Looks like this was fixed in Jest after we migrated the equality check: jestjs/jest#8359

[hi-ogawa]

Note that also the iterator is ignored, the following keeps passing: ...

This one might be some this/bind issue?

> x = { [Symbol.iterator]: ["a", "b"][Symbol.iterator] }
{ [Symbol(Symbol.iterator)]: [Function: values] }
> x[Symbol.iterator]().next()
{ value: undefined, done: true }

> y = { [Symbol.iterator]: () => ["a", "b"][Symbol.iterator]() }
{ [Symbol(Symbol.iterator)]: [Function: [Symbol.iterator]] }
> y[Symbol.iterator]().next()
{ value: 'a', done: false }

[hi-ogawa]

Closed by #5621

[sheremet-va]

The fix should be in https://github.com/vitest-dev/vitest/releases/tag/v1.5.3

I checked and effect repo is now failing - are these errors expected?

[mikearnaldi]

Thank you very much for checking, this issue actually highlighted that we were running in a limbo relying on the fact that only iterable would be compared, we are working on custom matchers to fill the gap Effect-TS/effect#2646