Merge pull request #242 from mearns/issue/21

#21 Add support for FORCE_NO_COLOR env var

README.md

@@ -94,14 +94,16 @@ I prefer the first way. Some people seem to be afraid of extending `String.proto
 
 If you are writing good code you will never have an issue with the first approach. If you really don't want to touch `String.prototype`, the second usage will not touch `String` native object.
 
-## Disabling Colors
+## Forcing Colors to be Enabled/Disabled
 
 To disable colors you can pass the following arguments in the command line to your application:
 
 ```bash
 node myapp.js --no-color
 ```
 
+Alternatively, you can define an environment variable named `FORCE_COLOR` to force colors to be enabled (e.g. in a complex environment where colors support is not detected properly), or `FORCE_NO_COLOR` to force colors to be disabled; the environment variables will take effect if any non-zero value is specified.
+
 ## Console.log [string substitution](http://nodejs.org/docs/latest/api/console.html#console_console_log_data)
 
 ```js

lib/system/has-env-flag.js

@@ -0,0 +1,31 @@
+/*
+MIT License
+
+Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (sindresorhus.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+'use strict';
+
+module.exports = function(flag, env) {
+  env = env || process.env;
+  return (flag in env) &&
+    (env[flag].length === 0 || parseInt(env[flag], 10) !== 0);
+};

lib/system/supports-colors.js

@@ -27,6 +27,7 @@ THE SOFTWARE.
 
 var os = require('os');
 var hasFlag = require('./has-flag.js');
+var hasEnvFlag = require('./has-env-flag.js');
 
 var env = process.env;
 
@@ -37,9 +38,19 @@ if (hasFlag('no-color') || hasFlag('no-colors') || hasFlag('color=false')) {
            || hasFlag('color=always')) {
   forceColor = true;
 }
-if ('FORCE_COLOR' in env) {
-  forceColor = env.FORCE_COLOR.length === 0
-    || parseInt(env.FORCE_COLOR, 10) !== 0;
+
+var forceColorFromEnv = hasEnvFlag('FORCE_COLOR', env);
+var forceNoColorFromEnv = hasEnvFlag('FORCE_NO_COLOR', env);
+if (forceColorFromEnv) {
+  if (forceNoColorFromEnv && process.emitWarning) {
+    process.emitWarning(
+      'FORCE_COLOR and FORCE_NO_COLOR env vars are both set and conflicting, ' +
+      'going with FORCE_COLOR.'
+    );
+  }
+  forceColor = true;
+} else if (forceNoColorFromEnv) {
+  forceColor = false;
 }
 
 function translateLevel(level) {

tests/basic-test.js

@@ -70,4 +70,4 @@ assert.equal(colors.custom(s),
 colors.setTheme({custom: ['red', 'italic', 'inverse']});
 assert.equal(colors.custom(s),
   '\x1b[31m' + '\x1b[3m' + '\x1b[7m' + s +
-  '\x1b[27m' + '\x1b[23m' + '\x1b[39m' );
+  '\x1b[27m' + '\x1b[23m' + '\x1b[39m' );