If cannabis was harvested in 2017, and also tested in 2017, does it need to be retested in order to be sold after July 1?

Yes. Testing conducted prior to January 1, 2018, cannot be used to satisfy any state testing requirements because it was not carried out by a licensed lab. From the perspective of state regulators, products tested prior to January 1, 2018 are effectively “untested product” and must be either retested or destroyed following July 1.