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Node.js 12.0.0 changes how arrays with symbol properties are compared using deepEqual() #27652
Description
Hi, it looks like Node 12 changed how arrays are compared with deepEqual(), presumably due to https://github.com/nodejs/node/pull/25008/files . Here's an example of how deepEqual() handles arrays with symbol properties:
const assert = require('assert');
console.log(process.version);
const s = Symbol('foo');
const arr = [];
arr[s] = 42;
assert.deepEqual(arr, []);Running this script with Node.js 11.9.0 succeeds:
$ ~/Workspace/libs/node-v11.9.0-linux-x64/bin/node test.js
v11.9.0
$
Running with Node.js 12 fails:
$ ~/Workspace/libs/node-v12.0.0-linux-x64/bin/node test.js
v12.0.0
assert.js:89
throw new AssertionError(obj);
^
AssertionError [ERR_ASSERTION]: Expected values to be loosely deep-equal:
[
[Symbol(foo)]: 42
]
should equal
[]
$
Is this a bug or expected behavior? If so, you should update the legacy mode deepEqual() docs, which explicitly state that symbol properties are ignored.
Related to Automattic/mongoose#7784.
Activity
targos commentedon May 11, 2019
/cc @nodejs/assert @BridgeAR
BridgeAR commentedon May 11, 2019
This was indeed an unintentional change and I missed that the array optimization currently always gets the symbol properties even though the loose equal comparison should not compare symbol properties. I'll open a PR to fix that.
assert: loose deep equal should not compare symbol properties
assert: loose deep equal should not compare symbol properties
assert: loose deep equal should not compare symbol properties