Sample

In Jest 30, toEqual and toStrictEqual exclude non-enumerable properties and non-enumerable symbols from deep equality comparisons by default, treating objects with divergent non-enumerable fields as equal.

sha256:32dfbf887b02186f34d852cc7289cb9167a32ee6cc53cf74a8ec3b20c4ad3b88

PUBLISHED L3_CONTRACT_PASS MIT-0

Case

Goal: In Jest 30, toEqual and toStrictEqual exclude non-enumerable properties and non-enumerable symbols from deep equality comparisons by default, treating objects with divergent non-enumerable fields as equal. HOW
Packages: jest 30.4.2
Environment: node
Created: 2026-08-17T01:56:53Z

Commonly assumed

expect(received).toEqual(expected) and expect(received).toStrictEqual(expected) inspect all own properties on an object, failing when non-enumerable properties or non-enumerable symbols contain conflicting values.

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

expect(received).toEqual(expected) and expect(received).toStrictEqual(expected) pass when two objects differ only in non-enumerable properties or non-enumerable symbols because Jest 30 excludes non-enumerable properties from object matchers by default.
Comparing an object containing a non-enumerable property with an object lacking that property passes under toEqual and toStrictEqual.
expect.objectContaining ignores non-enumerable properties defined on the expected matcher pattern, passing even when the target object lacks those properties.
expect(received).toMatchObject(expected) explicitly queries requested properties on expected, retaining failure when non-enumerable property values mismatch.
Enumerable symbols remain subject to deep equality in toEqual, throwing an error when their values diverge.

Files

NOTES.md
csx.json
package-lock.json
package.json
test/contract.mjs

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

csx-seed

Verification receipts

node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9