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

I think there's a difference with --test, because process.env.FORCE_COLOR is set to 1. In this case: the shouldColorize() method forces the color (by getColorDepth() unless FORCE_COLOR is different from '', '1', 'true', '2' and '3').

node/lib/internal/util/colors.js

Lines 18 to 25 in 6cdcaa9

    
           shouldColorize(stream) { 
        
             if (process.env.FORCE_COLOR !== undefined) { 
        
               return lazyInternalTTY().getColorDepth() > 2; 
        
             } 
        
             return stream?.isTTY && ( 
        
               typeof stream.getColorDepth === 'function' ? 
        
                 stream.getColorDepth() > 2 : true); 
        
           },

I think it's this line that forces the color:

node/lib/internal/test_runner/runner.js

Lines 375 to 377 in 6cdcaa9

    
           if (opts.root.harness.shouldColorizeTestFiles) { 
        
             env.FORCE_COLOR = '1'; 
        
           }

The shouldColorizeTestFiles() method uses shouldColorize().

node/lib/internal/test_runner/utils.js

Lines 145 to 151 in 6cdcaa9

    
           function shouldColorizeTestFiles(destinations) { 
        
             // This function assumes only built-in destinations (stdout/stderr) supports coloring 
        
             return ArrayPrototypeSome(destinations, (_, index) => { 
        
               const destination = kBuiltinDestinations.get(destinations[index]); 
        
               return destination && shouldColorize(destination); 
        
             }); 
        
           }

I don't think you should force color when it's supported. It should be the functions that stylize the test results that should call shouldColorize() to check whether they are adding color. This already seems to be the case in lib/internal/test_runner/reporter/utils.js.

This issue has been marked as stale due to 210 days of inactivity.
It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.

I tested it with Node v25.9.0 and I'm still having the problem.

This issue has been marked as stale due to 90 days of inactivity.
It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.

The problem still exists in Node v26.5.0

lib,test_runner: fix styleText colorizing non-TTY streams under --test

Navigation Menu

Repository navigation

`styleText()`: isTTY check fails with `--test` #57921

Version

Platform

Subsystem

What steps will reproduce the bug?

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

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

What do you see instead?

Additional information

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

	shouldColorize(stream) {
	if (process.env.FORCE_COLOR !== undefined) {
	return lazyInternalTTY().getColorDepth() > 2;
	}
	return stream?.isTTY && (
	typeof stream.getColorDepth === 'function' ?
	stream.getColorDepth() > 2 : true);
	},

	if (opts.root.harness.shouldColorizeTestFiles) {
	env.FORCE_COLOR = '1';
	}

	function shouldColorizeTestFiles(destinations) {
	// This function assumes only built-in destinations (stdout/stderr) supports coloring
	return ArrayPrototypeSome(destinations, (_, index) => {
	const destination = kBuiltinDestinations.get(destinations[index]);
	return destination && shouldColorize(destination);
	});
	}

styleText(): isTTY check fails with --test #57921

Description

Version

Platform

Subsystem

What steps will reproduce the bug?

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

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

What do you see instead?

Additional information

Activity

regseb commented on Apr 18, 2025

github-actions commented on Apr 20, 2026

regseb commented on Apr 20, 2026

github-actions commented on Jul 20, 2026

regseb commented on Jul 28, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

`styleText()`: isTTY check fails with `--test` #57921