tty: truecolor check moved before 256 check

[duncanhealy]

256 color would be return instead of 16m if both env variables were set
Test added to pseudo-tty/test-tty-color-support
Related Issue: #27609

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[BridgeAR]

LGTM. Thanks for the fix!

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26571/

[lpinca]

I looks like this if statement can be removed, if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit') { /* ... */ } is sufficient.

[duncanhealy]

Hi @lpinca this is to catch the case when no TERM environment variable is set
without this COLORS_2 is returned which fails an existing test

[lpinca]

I don't get it, if env.COLORTERM is truthy, COLORS_16m is returned only if env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit' otherwise nothing is done so why not using only

if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
  return COLORS_16m;

[duncanhealy]

COLORTERM can be set to values other than truecolor and 24bit . yes no gnome-terminal are other values used. We want to return the higest spec tty capability available first. If you remove the second check for env.COLORTERM you miss the case when TERM is not set but COLORTERM is not truecolor or 24bit. If you leave the code as it was before you get 256 color terminal when your terminal is capable of 16M. Basically we are moving the COLORS_256 check inbetween the COLORS_16m and the COLORS_16 checks

[lpinca]

FWIW this is what I'm suggesting

diff --git a/lib/internal/tty.js b/lib/internal/tty.js
index faf5df9b42..63832ef220 100644
--- a/lib/internal/tty.js
+++ b/lib/internal/tty.js
@@ -173,6 +173,9 @@ function getColorDepth(env = process.env) {
       return COLORS_256;
   }
 
+  if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
+    return COLORS_16m;
+
   if (env.TERM) {
     if (/^xterm-256/.test(env.TERM))
       return COLORS_256;
@@ -188,13 +191,10 @@ function getColorDepth(env = process.env) {
       }
     }
   }
-
+  // Move 16 color COLORTERM below 16m and 256
   if (env.COLORTERM) {
-    if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
-      return COLORS_16m;
     return COLORS_16;
   }
-
   return COLORS_2;
 }
 
diff --git a/test/pseudo-tty/test-tty-color-support.js b/test/pseudo-tty/test-tty-color-support.js
index b2cfc804c3..57ed640d4d 100644
--- a/test/pseudo-tty/test-tty-color-support.js
+++ b/test/pseudo-tty/test-tty-color-support.js
@@ -71,6 +71,7 @@ const writeStream = new WriteStream(fd);
   [{ NO_COLOR: '', COLORTERM: '24bit' }, 1],
   [{ TMUX: '1', FORCE_COLOR: 0 }, 1],
   [{ NO_COLOR: 'true', FORCE_COLOR: 0, COLORTERM: 'truecolor' }, 1],
+  [{ TERM: 'xterm-256color', COLORTERM: 'truecolor' }, 24],
 ].forEach(([env, depth], i) => {
   const actual = writeStream.getColorDepth(env);
   assert.strictEqual(

[lpinca]

if (env.COLORTERM) {
  if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
    return COLORS_16m;
}

is equal to

if (
  env.COLORTERM &&
  (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
) {
  return COLORS_16m;
}

which is equal to

if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit') {
  return COLORS_16m;
}

[duncanhealy]

if you remove the bottom if and make test you can see the case when it fails

[lpinca]

I've applied the patch in my previous comment and tests pass.

What you mean with bottom if? The one on line 197? If so I'm not suggesting to remove it. I never did. Anyway it does not matter, it is not very important :)

[duncanhealy]

ok yes we can remove the nested if - I thought you were talking about the second if (env.COLORTERM) - I'll update the pull request now

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/26670/

[addaleax]

Landed in 80ac428, thanks for the PR! 🎉