From 226e4d90dacdac0019866f805cf93179cb00d2f9 Mon Sep 17 00:00:00 2001
From: Sindre Sorhus <sindresorhus@gmail.com>
Date: Fri, 29 Sep 2017 10:10:29 +0700
Subject: [PATCH] Clean up #4

---
 index.js |  4 ++--
 test.js  | 14 +++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/index.js b/index.js
index 02036be..045577f 100644
--- a/index.js
+++ b/index.js
@@ -84,8 +84,8 @@ is.promise = x => is.nativePromise(x) || hasPromiseAPI(x);
 
 is.generator = x => is.iterable(x) && is.function(x.next) && is.function(x.throw);
 
-// Change to use `isObjectOfType` once Node 4.x.x LTS is dropped
-is.generatorFunction = x => x.constructor.name === 'GeneratorFunction';
+// TODO: Change to use `isObjectOfType` once Node.js 6 or higher is targeted
+is.generatorFunction = x => is.function(x) && is.function(x.constructor) && x.constructor.name === 'GeneratorFunction';
 
 is.regExp = isObjectOfType('RegExp');
 is.date = isObjectOfType('Date');
diff --git a/test.js b/test.js
index 89b4a41..b4b50e6 100644
--- a/test.js
+++ b/test.js
@@ -59,8 +59,11 @@ const types = new Map([
 	]],
 	['promise', {then() {}, catch() {}}],
 	['generator', (function * () {
-		yield 42;
+		yield 4;
 	})()],
+	['generatorFunction', function * () {
+		yield 4;
+	}],
 	['map', new Map()],
 	['set', new Set()],
 	['weakMap', new WeakMap()],
@@ -138,7 +141,7 @@ test('is.array', t => {
 });
 
 test('is.function', t => {
-	testType(t, 'function');
+	testType(t, 'function', ['generatorFunction']);
 });
 
 test('is.buffer', t => {
@@ -174,14 +177,11 @@ if (isNode8orHigher) {
 }
 
 test('is.generator', t => {
-	testType(t, 'generator', ['function']);
+	testType(t, 'generator');
 });
 
 test('is.generatorFunction', t => {
-	const gen = function * () {
-		yield 42;
-	};
-	t.true(m.generatorFunction(gen));
+	testType(t, 'generatorFunction', ['function']);
 });
 
 test('is.map', t => {