deepStrictEqual diff is unhelpful when prototype mismatches

Version

v20.8.0

Platform

Darwin Me.local 23.0.0 Darwin Kernel Version 23.0.0: Fri Sep 15 14:41:34 PDT 2023; root:xnu-10002.1.13~1/RELEASE_ARM64_T8103 arm64

Subsystem

No response

What steps will reproduce the bug?

Given repo.js

import { test } from "node:test";
import { deepStrictEqual, notDeepStrictEqual } from "node:assert";

class ExtendedArray extends Array {
  constructor() {
    super();
  }
}

test("deepStrictEqual should print prototype diff", () => {
  const actual = new ExtendedArray();
  actual[0] = "hello";
  const expected = ["hello"];

  notDeepStrictEqual(
    Object.getPrototypeOf(actual),
    Object.getPrototypeOf(expected)
  );

  deepStrictEqual(actual, expected);
});

Run node --test repo.js.

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

deepStrictEquals requires actual and expected to have the same prototype, but fails to show error message describing if they are not the same.

A more helpful diff would be:

$ node --test repo.js
✖ deepStrictEqual should print prototype diff (1.581625ms)
  AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
  + actual - expected
  
  + ExtendedArray(1) [
  - [
      'hello'
    ]
      at TestContext.<anonymous> (file://.../repo.js:20:3)
      at Test.runInAsyncScope (node:async_hooks:206:9)
      at Test.run (node:internal/test_runner/test:631:25)
      at Test.start (node:internal/test_runner/test:542:17)
      at startSubtest (node:internal/test_runner/harness:208:17) {
    generatedMessage: true,
    code: 'ERR_ASSERTION',
    actual prototype: Array {}
    expected prototype: Object(0) [],
    operator: 'deepStrictEqual'
  }

What do you see instead?

Only the contents of the arrays are diffed.

$ node --test repo.js
✖ deepStrictEqual should print prototype diff (1.581625ms)
  AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
  + actual - expected
  
  + ExtendedArray(1) [
  - [
      'hello'
    ]
      at TestContext.<anonymous> (file://.../repo.js:20:3)
      at Test.runInAsyncScope (node:async_hooks:206:9)
      at Test.run (node:internal/test_runner/test:631:25)
      at Test.start (node:internal/test_runner/test:542:17)
      at startSubtest (node:internal/test_runner/harness:208:17) {
    generatedMessage: true,
    code: 'ERR_ASSERTION',
    actual: [ 'hello' ],
    expected: [ 'hello' ],
    operator: 'deepStrictEqual'
  }

Additional information

No response

repo.js の再現コードから始め、node --test repo.js を実行して現在のアサーション出力を確認します。node:assert deepStrictEqual の失敗時のフォーマットを追跡して回帰テストを追加します。完了条件は、一致しないプロトタイプが diff に表現され、既存の配列の内容が引き続き正しく報告されることです。