From 18cb9822fe4f1a745158ae532872c9db4f3f6e29 Mon Sep 17 00:00:00 2001
From: "Hongyang Du (hond)" <hond@microsoft.com>
Date: Tue, 28 Apr 2020 14:45:18 +0800
Subject: [PATCH] [PORT][Expression]fix null check in expression (#2118)

---
 .../src/expressionFunctions.ts                    |  4 ++--
 .../tests/expressionParser.test.js                | 15 +++++++++++++--
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/libraries/adaptive-expressions/src/expressionFunctions.ts b/libraries/adaptive-expressions/src/expressionFunctions.ts
index 044517f1fb..8166549a7e 100644
--- a/libraries/adaptive-expressions/src/expressionFunctions.ts
+++ b/libraries/adaptive-expressions/src/expressionFunctions.ts
@@ -1838,8 +1838,8 @@ export class ExpressionFunctions {
             return false;
         }
 
-        if (args[0] === undefined || args[0] === null) {
-            return args[1] === undefined || args[1] === null;
+        if (args[0] === undefined || args[0] === null || args[1] === undefined || args[1] === null) {
+            return (args[0] === undefined || args[0] === null) && (args[1] === undefined || args[1] === null);
         }
 
         if (Array.isArray(args[0]) && args[0].length === 0 && Array.isArray(args[1]) && args[1].length === 0) {
diff --git a/libraries/adaptive-expressions/tests/expressionParser.test.js b/libraries/adaptive-expressions/tests/expressionParser.test.js
index d6fc3bb2e7..7e36ad5d85 100644
--- a/libraries/adaptive-expressions/tests/expressionParser.test.js
+++ b/libraries/adaptive-expressions/tests/expressionParser.test.js
@@ -317,7 +317,18 @@ const dataSource = [
     ['emptyList == {  }', false],
     ['emptyObject == {  }', true],
     ['emptyObject == [  ]', false],
-    
+    ['{} == undefined', false],
+    ['{} != undefined', true],
+    ['[] == undefined', false],
+    ['{} != undefined', true],
+    ['{} == null', false],
+    ['{} != null', true],
+    ['[] == null', false],
+    ['{} != null', true],
+    ['{} == {}', true],
+    ['[] == []', true],
+    ['{} != []', true],
+    ['[] == {}', false],
 
     // Conversion functions tests
     ['float(\'10.333\')', 10.333],
@@ -632,7 +643,7 @@ const dataSource = [
 ];
 
 const scope = {
-    "$index": "index",
+    '$index': 'index',
     alist: [
         {
             Name: 'item1'