From adc248f6395cb7319f5db97c2208bd8bceb089f9 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Sat, 25 Nov 2017 14:02:24 -0500
Subject: [PATCH] make target store optional

---
 store.js            | 3 ++-
 test/store/index.js | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/store.js b/store.js
index 2c573b247f..9c3962d63b 100644
--- a/store.js
+++ b/store.js
@@ -149,7 +149,8 @@ assign(Store.prototype, {
 	}
 });
 
-function combineStores(store, children) {
+function combineStores(children, store) {
+	if (!store) store = new Store();
 	var updates = {};
 
 	for (const key in children) {
diff --git a/test/store/index.js b/test/store/index.js
index 2f5666152c..246e655229 100644
--- a/test/store/index.js
+++ b/test/store/index.js
@@ -160,7 +160,7 @@ describe.only('store', () => {
 
 			b.compute('z', ['x', 'y'], (x, y) => x + y);
 
-			const c = combineStores(new Store(), { a, b });
+			const c = combineStores({ a, b });
 
 			c.compute('total', ['a', 'b'], (a, b) => a.z + b.z);