Most packaging materials are sensitive to the climate. Paper based materials are sensitive to the humidity and plastic to temperature. For this reason the package and the product have to be tested under conditions near to the real environment and in the same climate conditions every time. Public testing institutes are normally using the standard climate of 23 0C and 50% humidity. You must decide a relevant climate for your packed product.
Make sure that the packaging you are going to test have adapted to the new climate. Both product and packaging system need time to be in balance - 1-3 days and min. 24 hours.
Transport, handeling and storege of your packaging will happen in many and also bad climate. You must design the test conditions near to the worst conditions in your distribution.
You do not need to make the test in the bad conditions. You can do conditioning in a climate chamber and within a short time perform testing in another room. After about 1 hour of testing the packed product must be back in the climate chamber.