Added GenericStringBuffer::GetSize() within unit test, as in 0.1x branch.

git-svn-id: https://rapidjson.googlecode.com/svn/trunk@61 c5894555-1306-4e8d-425f-1f6f381ee07c

test/unittest/writertest.cpp

@@ -12,6 +12,7 @@ TEST(Writer, Compact) {
 	Reader reader;
 	reader.Parse<0>(s, writer);
 	EXPECT_STREQ("{\"hello\":\"world\",\"t\":true,\"f\":false,\"n\":null,\"i\":123,\"pi\":3.1416,\"a\":[1,2,3]}", buffer.GetString());
+	EXPECT_EQ(77, buffer.GetSize());
 }
 
 // json -> parse -> writer -> json