Add timeout option (#4)

index.js

@@ -1,4 +1,6 @@
 'use strict';
+const pTimeout = require('p-timeout');
+
 module.exports = (emitter, event, opts) => {
 	let cancel;
 
@@ -55,5 +57,9 @@ module.exports = (emitter, event, opts) => {
 
 	ret.cancel = cancel;
 
+	if (typeof opts.timeout === 'number') {
+		return pTimeout(ret, opts.timeout);
+	}
+
 	return ret;
 };

package.json

@@ -41,6 +41,9 @@
     "promises",
     "bluebird"
   ],
+  "dependencies": {
+    "p-timeout": "^1.1.1"
+  },
   "devDependencies": {
     "ava": "*",
     "delay": "^1.3.1",

readme.md

@@ -93,6 +93,13 @@ pEvent(emitter, 'finish', {multiArgs: true}).then(result => {
 });
 ```
 
+##### timeout
+
+Type: `Number`<br>
+Default: `Infinity`
+
+Time in milliseconds before timing out.
+
 
 ## Before and after
 

test.js

@@ -95,3 +95,28 @@ test('event to promise - error', async t => {
 
 	t.deepEqual(await m(emitter, 'error'), new Error('💩'));
 });
+
+test('`timeout` option rejects when short enough', async t => {
+	const emitter = new EventEmitter();
+	const timeout = 50;
+
+	delay(200).then(() => {
+		emitter.emit('🦄', '🌈');
+	});
+
+	await t.throws(m(emitter, '🦄', {
+		timeout
+	}), `Promise timed out after ${timeout} milliseconds`);
+});
+
+test('`timeout` option resolves when long enough', async t => {
+	const emitter = new EventEmitter();
+
+	delay(200).then(() => {
+		emitter.emit('🦄', '🌈');
+	});
+
+	t.is(await m(emitter, '🦄', {
+		timeout: 250
+	}), '🌈');
+});