I was reading this article about an "EmDrive" recently. The article suggests that we've just been looking at the problem the wrong way all along, which sounds either like genius or lunacy. What would it take for someone (a space organization like NASA or the ESA) to test the viability of such a device to the extent that there is no doubt it works?
NASA's already testing the EmDrive, at the NASA/JSC Advanced Propulsion Physics Laboratory.
To have no doubt that the device works, we'd need to see the test results replicated consistently by multiple laboratories. As of early 2016, 3 laboratories have done tests with inconsistent results (different levels of thrust/input power).
It'd also be nice to understand how the thing works. As the article linked in the question says, there are some interesting hypotheses which would revolutionize physics if they can be confirmed.