There is no such thing, critics will always find faults in "test".
I am not a critic in the sense you have in mind. I would be satisfied with a properly done test. So would the people at I.H. They would have paid Rossi $89 million for a properly done test. He knew what they demanded. If his device worked, he would have done a proper test, and he would now have the money. It would have taken a few hours, not a year.
For the record, properly done tests are defined by the ASME and written into the Florida regulations for boilers. There is no question about what these tests consist of. Hundreds of thousands of HVAC engineers are trained to perform these tests. If the claims were true, any one of these people could produce irrefutable proof the machine works as claimed. This proof would be so rock solid you could bet your life on it. You do bet your life on it, every time you go into a building with a boiler. Before the ASME was founded in 1880, people were killed every day by exploding boilers in buildings, factories, ships and elsewhere.
The only "test" is a customer making money using LENR.