Support 256 color output on Windows 10 (#56)

index.js

@@ -1,4 +1,5 @@
 'use strict';
+const os = require('os');
 const hasFlag = require('has-flag');
 
 const env = process.env;
@@ -45,6 +46,20 @@ let supportLevel = (() => {
 	}
 
 	if (process.platform === 'win32') {
+		// Node.js 7.5.0 is the first version of Node.js to include a patch to
+		// libuv that enables 256 color output on Windows. Anything earlier and it
+		// won't work. However, here we target Node.js 8 at minimum as it is an LTS
+		// release, and Node.js 7 is not. Windows 10 build 10586 is the first Windows
+		// release that supports 256 colors.
+		const osRelease = os.release().split('.');
+		if (
+			Number(process.version.split('.')[0]) >= 8 &&
+			Number(osRelease[0]) >= 10 &&
+			Number(osRelease[2]) >= 10586
+		) {
+			return 2;
+		}
+
 		return 1;
 	}
 

test.js

@@ -1,7 +1,11 @@
+import os from 'os';
 import {serial as test} from 'ava';
 import importFresh from 'import-fresh';
 
 test.beforeEach(() => {
+	Object.defineProperty(process, 'platform', {
+		value: 'linux'
+	});
 	process.stdout.isTTY = true;
 	process.argv = [];
 	process.env = {};
@@ -185,6 +189,9 @@ test('support screen-256color', t => {
 });
 
 test('level should be 3 when using iTerm 3.0', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'darwin'
+	});
 	process.env = {
 		TERM_PROGRAM: 'iTerm.app',
 		TERM_PROGRAM_VERSION: '3.0.10'
@@ -194,10 +201,61 @@ test('level should be 3 when using iTerm 3.0', t => {
 });
 
 test('level should be 2 when using iTerm 2.9', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'darwin'
+	});
 	process.env = {
 		TERM_PROGRAM: 'iTerm.app',
 		TERM_PROGRAM_VERSION: '2.9.3'
 	};
 	const result = importFresh('.');
 	t.is(result.level, 2);
 });
+
+test('return level 1 if on Windows earlier than 10 build 10586 and Node version is < 8.0.0', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'win32'
+	});
+	Object.defineProperty(process, 'version', {
+		value: '7.5.0'
+	});
+	os.release = () => '10.0.10240';
+	const result = importFresh('.');
+	t.is(result.level, 1);
+});
+
+test('return level 1 if on Windows 10 build 10586 or later and Node version is < 8.0.0', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'win32'
+	});
+	Object.defineProperty(process, 'version', {
+		value: '7.5.0'
+	});
+	os.release = () => '10.0.10586';
+	const result = importFresh('.');
+	t.is(result.level, 1);
+});
+
+test('return level 1 if on Windows earlier than 10 build 10586 and Node version is >= 8.0.0', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'win32'
+	});
+	Object.defineProperty(process, 'version', {
+		value: '8.0.0'
+	});
+	os.release = () => '10.0.10240';
+	const result = importFresh('.');
+	t.is(result.level, 1);
+});
+
+test('return level 2 if on Windows 10 build 10586 or later and Node version is >= 8.0.0', t => {
+	Object.defineProperty(process, 'platform', {
+		value: 'win32'
+	});
+	Object.defineProperty(process, 'version', {
+		value: '8.0.0'
+	});
+	os.release = () => '10.0.10586';
+	const result = importFresh('.');
+	t.is(result.level, 2);
+});