[tool] add IsStringNullOrEmpty() test

Author: mydeveloperday

src/framework/NetString.h

@@ -222,7 +222,7 @@ namespace System
 
         static bool IsNullOrEmpty(const String &s)
         {
-           retunr (s.Length()==0);
+           return (s.Length()==0);
         }
     };
 

src/unittests/String_Test.cxx

@@ -136,3 +136,9 @@ TEST(StringTest, Trim)
     EXPECT_EQ(String("Hello"),String("Hello").TrimEnd());
     EXPECT_EQ(String("   Hello"),String("   Hello   ").TrimEnd());
 }
+
+TEST(StringTest, NullOrEmpty)
+{
+    EXPECT_FALSE(String::IsStringNullOrEmpty(String("Hello")));
+    EXPECT_TRUE(String::IsStringNullOrEmpty(String("")));
+}