Add option to exclude -g argument from default update message (#105)

index.js

@@ -107,10 +107,10 @@ class UpdateNotifier {
 			return this;
 		}
 
-		opts = opts || {};
+		opts = Object.assign({isGlobal: true}, opts);
 
 		opts.message = opts.message || 'Update available ' + chalk().dim(this.update.current) + chalk().reset(' → ') +
-			chalk().green(this.update.latest) + ' \nRun ' + chalk().cyan('npm i -g ' + this.packageName) + ' to update';
+			chalk().green(this.update.latest) + ' \nRun ' + chalk().cyan('npm i ' + (opts.isGlobal ? '-g ' : '') + this.packageName) + ' to update';
 
 		opts.boxenOpts = opts.boxenOpts || {
 			padding: 1,

readme.md

@@ -131,6 +131,13 @@ Default: [See above screenshot](https://github.com/yeoman/update-notifier#update
 
 Message that will be shown when an update is available.
 
+##### isGlobal
+
+Type: `boolean`<br>
+Default: `true`
+
+Include the `-g` argument in the default message's `npm i` recommendation. You may want to change this if your CLI package can be installed as a dependency of another project, and don't want to recommend a global installation. This option is ignored if you supply your own `message` (see above).
+
 ##### boxenOpts
 
 Type: `Object`<br>

test.js

@@ -97,6 +97,15 @@ describe('notify(opts)', () => {
 		updateNotifier = require('./');
 	});
 
+	function Control() {
+		this.packageName = 'update-notifier-tester';
+		this.update = {
+			current: '0.0.2',
+			latest: '1.0.0'
+		};
+	}
+	util.inherits(Control, updateNotifier.UpdateNotifier);
+
 	let errorLogs = '';
 
 	beforeEach(() => {
@@ -112,14 +121,6 @@ describe('notify(opts)', () => {
 	});
 
 	it('should use pretty boxen message by default', () => {
-		function Control() {
-			this.packageName = 'update-notifier-tester';
-			this.update = {
-				current: '0.0.2',
-				latest: '1.0.0'
-			};
-		}
-		util.inherits(Control, updateNotifier.UpdateNotifier);
 		const notifier = new Control();
 		notifier.notify({defer: false});
 		assert.equal(stripAnsi(errorLogs), [
@@ -135,4 +136,11 @@ describe('notify(opts)', () => {
 			''
 		].join('\n'));
 	});
+
+	it('should exclude -g argument when `isGlobal` option is `false`', () => {
+		const notifier = new Control();
+		notifier.notify({defer: false, isGlobal: false});
+		assert.notEqual(-1, stripAnsi(errorLogs)
+			.indexOf('Run npm i update-notifier-tester to update'));
+	});
 });