Added a test class for StringBuilder

JsonGeneratorTests/StringBuilderTests.cpp

@@ -0,0 +1,32 @@
+#include "CppUnitTest.h"
+#include "StringBuilder.h"
+
+using namespace Microsoft::VisualStudio::CppUnitTestFramework;
+
+namespace JsonGeneratorTests
+{
+    TEST_CLASS(StringBuilderTests)
+    {
+        char buffer[16];
+        StringBuilder* sb;
+
+
+    public:
+
+        TEST_METHOD_INITIALIZE(Initialize)
+        {
+            sb = new StringBuilder(buffer, sizeof(buffer));
+        }
+        
+        TEST_METHOD(InitialState)
+        {
+            assertResultIs("");
+        }
+
+
+        void assertResultIs(const char* expected)
+        {
+            Assert::AreEqual(expected, buffer);
+        }
+    };
+}