Added a tests of a string with a double quote in it

JsonGeneratorTests/JsonArrayTests.cpp

@@ -30,6 +30,13 @@ namespace JsonGeneratorTests
             AssertJsonIs("[\"hello\"]");
         }
 
+        TEST_METHOD(AddOneStringContainingDoubleQuote)
+        {
+            arr.add("\"");
+
+            AssertJsonIs("[\"\\\"\"]");
+        }
+
         TEST_METHOD(AddTwoStrings)
         {
             arr.add("hello");