I am pretty certain Comey is not going to testify on anything.
It looks to be all be set up for Comey to testify in open session next week and assert that Trump attempted to interfere in the Flynn investigation. He may submit his own personal notes and testify that they were made the same day as Trump's alleged. Won't matter to the mob that there is no proof. With the Uniparty in full throated hunt to get Trump out of office, there will be howls for impeachment immediately.
Given the clowns on our side, I'll be surprised if he doesn't end up in the White House.