repl: check colors with .getColorDepth()

PR-URL: #26261
Fixes: #26187
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

lib/repl.js

@@ -504,7 +504,9 @@ function REPLServer(prompt,
   self.writer = options.writer || exports.writer;
 
   if (options.useColors === undefined) {
-    options.useColors = self.terminal;
+    options.useColors = self.terminal && (
+      typeof self.outputStream.getColorDepth === 'function' ?
+        self.outputStream.getColorDepth() > 1 : true);
   }
   self.useColors = !!options.useColors;
 

test/pseudo-tty/repl-dumb-tty.js

@@ -0,0 +1,15 @@
+'use strict';
+require('../common');
+
+process.env.TERM = 'dumb';
+
+const repl = require('repl');
+
+repl.start('> ');
+process.stdin.push('console.log("foo")\n');
+process.stdin.push('1 + 2\n');
+process.stdin.push('"str"\n');
+process.stdin.push('console.dir({ a: 1 })\n');
+process.stdin.push('{ a: 1 }\n');
+process.stdin.push('\n');
+process.stdin.push('.exit\n');

test/pseudo-tty/repl-dumb-tty.out

@@ -0,0 +1,14 @@
+> console.log("foo")
+foo
+undefined
+> 1 + 2
+3
+> "str"
+'str'
+> console.dir({ a: 1 })
+{ a: 1 }
+undefined
+> { a: 1 }
+{ a: 1 }
+>
+> .exit