Understand that the most likely gate of knowledge that this unlocks is, "oh, there was some kind of magnetic interaction between the test drive and the harness,

Understand that the most likely gate of knowledge that this unlocks is, "oh, there was some kind of magnetic interaction between the test drive and the harness," or something to that effect. The proper Bayesian approach to these tests is to downgrade your prior of "drives require reaction mass" from 99.99999999% to 99.999999%