From 887b736f39979c260495349629696243f349b92c Mon Sep 17 00:00:00 2001
From: harttle <yangjvn@126.com>
Date: Tue, 14 Aug 2018 00:01:17 +0800
Subject: [PATCH] test cases for stringify

---
 src/util/underscore.js  | 14 ++++++++------
 test/util/underscore.js |  6 ++++++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/util/underscore.js b/src/util/underscore.js
index f77828b08..37f233ef0 100644
--- a/src/util/underscore.js
+++ b/src/util/underscore.js
@@ -11,12 +11,14 @@ function isString (value) {
 }
 
 function stringify (value) {
-  if (!isNil(value)) {
-    if (typeof value.to_liquid === 'function') {
-      return stringify(value.to_liquid())
-    } else if (typeof value.toLiquid === 'function') {
-      return stringify(value.toLiquid())
-    }
+  if (isNil(value)) {
+    return String(value)
+  }
+  if (typeof value.to_liquid === 'function') {
+    return stringify(value.to_liquid())
+  }
+  if (typeof value.toLiquid === 'function') {
+    return stringify(value.toLiquid())
   }
   if (isString(value)) {
     return value
diff --git a/test/util/underscore.js b/test/util/underscore.js
index 8cfa8b897..ca365df2b 100644
--- a/test/util/underscore.js
+++ b/test/util/underscore.js
@@ -44,6 +44,12 @@ describe('util/underscore', function () {
     it('should recursively call toLiquid()', function () {
       expect(_.stringify({toLiquid: () => ({toLiquid: () => 'foo'})})).to.equal('foo')
     })
+    it('should return "null" for null', function () {
+      expect(_.stringify(null)).to.equal('null')
+    })
+    it('should return "undefined" for undefined', function () {
+      expect(_.stringify(undefined)).to.equal('undefined')
+    })
   })
   describe('.forOwn()', function () {
     it('should iterate all properties', function () {