tty: improve color detection

1) Using `process.env.TERM = 'dumb'` should never return any colors.
2) `process.env.TERM = 'terminator'` supports 24 bit colors.
3) Add support for `process.env.TERM = 'rxvt-unicode-24bit'`
4) `Hyper` does not support true colors anymore. It should fall back
   to the xterm settings in regular cases.
5) `process.env.COLORTERM = 'truecolor'` should return 24 bit colors.

PR-URL: #26264
Refs: #26261
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/tty.js

@@ -36,22 +36,25 @@ const COLORS_16m = 24;
 // Copyright (C) 1996-2016 Free Software Foundation, Inc. Copying and
 // distribution of this file, with or without modification, are permitted
 // provided the copyright notice and this notice are preserved.
-const TERM_ENVS = [
-  'eterm',
-  'cons25',
-  'console',
-  'cygwin',
-  'dtterm',
-  'gnome',
-  'hurd',
-  'jfbterm',
-  'konsole',
-  'kterm',
-  'mlterm',
-  'putty',
-  'st',
-  'terminator'
-];
+const TERM_ENVS = {
+  'eterm': COLORS_16,
+  'cons25': COLORS_16,
+  'console': COLORS_16,
+  'cygwin': COLORS_16,
+  'dtterm': COLORS_16,
+  'gnome': COLORS_16,
+  'hurd': COLORS_16,
+  'jfbterm': COLORS_16,
+  'konsole': COLORS_16,
+  'kterm': COLORS_16,
+  'mlterm': COLORS_16,
+  'putty': COLORS_16,
+  'st': COLORS_16,
+  // https://github.com/da-x/rxvt-unicode/tree/v9.22-with-24bit-color
+  'rxvt-unicode-24bit': COLORS_16m,
+  // https://gist.github.com/XVilka/8346728#gistcomment-2823421
+  'terminator': COLORS_16m
+};
 
 const TERM_ENVS_REG_EXP = [
   /ansi/,
@@ -68,7 +71,7 @@ const TERM_ENVS_REG_EXP = [
 // https://github.com/chalk/supports-color,
 // https://github.com/isaacs/color-support.
 function getColorDepth(env = process.env) {
-  if (env.NODE_DISABLE_COLORS || env.TERM === 'dumb' && !env.COLORTERM) {
+  if (env.NODE_DISABLE_COLORS || env.TERM === 'dumb') {
     return COLORS_2;
   }
 
@@ -117,7 +120,6 @@ function getColorDepth(env = process.env) {
       }
       return COLORS_16m;
     case 'HyperTerm':
-    case 'Hyper':
     case 'MacTerm':
       return COLORS_16m;
     case 'Apple_Terminal':
@@ -130,10 +132,8 @@ function getColorDepth(env = process.env) {
 
     const termEnv = env.TERM.toLowerCase();
 
-    for (const term of TERM_ENVS) {
-      if (termEnv === term) {
-        return COLORS_16;
-      }
+    if (TERM_ENVS[termEnv]) {
+      return TERM_ENVS[termEnv];
     }
     for (const term of TERM_ENVS_REG_EXP) {
       if (term.test(termEnv)) {
@@ -142,8 +142,11 @@ function getColorDepth(env = process.env) {
     }
   }
 
-  if (env.COLORTERM)
+  if (env.COLORTERM) {
+    if (env.COLORTERM === 'truecolor' || env.COLORTERM === '24bit')
+      return COLORS_16m;
     return COLORS_16;
+  }
 
   return COLORS_2;
 }

test/pseudo-tty/test-tty-get-color-depth.js

@@ -3,6 +3,7 @@
 const common = require('../common');
 const assert = require('assert').strict;
 const { WriteStream } = require('tty');
+const { inspect } = require('util');
 
 const fd = common.getTTYfd();
 const writeStream = new WriteStream(fd);
@@ -16,6 +17,8 @@ const writeStream = new WriteStream(fd);
 // Check different environment variables.
 [
   [{ COLORTERM: '1' }, 4],
+  [{ COLORTERM: 'truecolor' }, 24],
+  [{ COLORTERM: '24bit' }, 24],
   [{ TMUX: '1' }, 8],
   [{ CI: '1' }, 1],
   [{ CI: '1', TRAVIS: '1' }, 8],
@@ -29,7 +32,7 @@ const writeStream = new WriteStream(fd);
   [{ TERM_PROGRAM: 'iTerm.app', TERM_PROGRAM_VERSION: '3.0' }, 24],
   [{ TERM_PROGRAM: 'iTerm.app', TERM_PROGRAM_VERSION: '2.0' }, 8],
   [{ TERM_PROGRAM: 'HyperTerm' }, 24],
-  [{ TERM_PROGRAM: 'Hyper' }, 24],
+  [{ TERM_PROGRAM: 'Hyper' }, 1],
   [{ TERM_PROGRAM: 'MacTerm' }, 24],
   [{ TERM_PROGRAM: 'Apple_Terminal' }, 8],
   [{ TERM: 'xterm-256' }, 8],
@@ -40,13 +43,16 @@ const writeStream = new WriteStream(fd);
   [{ TERM: 'fail' }, 1],
   [{ NODE_DISABLE_COLORS: '1' }, 1],
   [{ TERM: 'dumb' }, 1],
-  [{ TERM: 'dumb', COLORTERM: '1' }, 4],
+  [{ TERM: 'dumb', COLORTERM: '1' }, 1],
+  [{ TERM: 'terminator' }, 24],
+  [{ TERM: 'console' }, 4]
 ].forEach(([env, depth], i) => {
   const actual = writeStream.getColorDepth(env);
   assert.strictEqual(
     actual,
     depth,
-    `i: ${i}, expected: ${depth}, actual: ${actual}, env: ${env}`
+    `i: ${i}, expected: ${depth}, ` +
+      `actual: ${actual}, env: ${inspect(env)}`
   );
 });