`styleText()`: isTTY check fails with `--test`

Version

v22.13.1

Platform

Linux 6.8.0-57-generic #59~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Wed Mar 19 17:07:41 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

Ubuntu 22.04.5 LTS

What steps will reproduce the bug?

• Create index.mjs:

  import { Writable } from "node:stream";
  import { styleText } from "node:util";
  
  const streamTTY = new class extends Writable {
      isTTY = true;
  };
  const streamNoTTY = new class extends Writable {
      isTTY = false;
  };
  
  console.log(styleText("bgYellow", "TTY", { stream: streamTTY }));
  console.log(styleText("bgYellow", "No TTY", { stream: streamNoTTY }));
  

• Run node index.mjs

• Run node --test index.mjs

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

Always.

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

The text No TTY isn't stylized with --test.

• node index.mjs

  ^[[43mTTY^[[49m
  No TTY
  

• node --test index.mjs

  ^[[43mTTY^[[49m
  No TTY
  ✔ index.mjs (27.022452ms)
  ...
  

What do you see instead?

The text No TTY is stylized with --test.

• node index.mjs

  ^[[43mTTY^[[49m
  No TTY
  

• node --test index.mjs

  ^[[43mTTY^[[49m
  ^[[43mNo TTY^[[49m
  ✔ index.mjs (27.022452ms)
  ...
  

Additional information

With the --test option, the styleText() function doesn't check whether the stream is TTY.

With the command line: node --test index.mjs > out.txt, the file contains the correct style:

TAP version 13
# ^[[43mTTY^[[49m
# No TTY
# Subtest: index.mjs
ok 1 - index.mjs
  ---
  duration_ms: 25.169793
  ...
1..1
# tests 1
# suites 0
# pass 1
# fail 0
# cancelled 0
# skipped 0
# todo 0
# duration_ms 30.191704

index.mjs の再現コードから始め、node index.mjs と node --test index.mjs の両方で実行し、TTY と non-TTY の出力を比較します。test runner がアクティブな間の styleText() による提供されたストリームの処理を追跡します。完了条件は、--test で non-TTY ストリームがスタイルなしのままになる一方、TTY のスタイリングとリダイレクトされた出力が現在の動作を維持することです。