For a revolutionary new type of propulsion, sodramjet (which hasn't been tested either in flight or on ground), it would have to be at least tested for even half a second (which is pretty darn long for a hypersonic wind tunnel) as there's absolutely no real world data to validate the software model. Otherwise no scientific or research institution in the world would have enough confidence to agree to spend at least a low eight figure USD sum to build a flying prototype.Have you ever heard of computer simulation software?
Basically most all designing phase testing is done with software such as Dassault Systemes Simulia ever before leaving the drawing board.
The reason why the US has been able to design and test a 6th generation fighter(within a year) so quickly is because of this kind of technology connected with super computers since the software relies heavily on the computation power.
This trend is the same with commercial automotive industry with initial design concept to proto typing within 18 months.
On the other hand, high mach wind tunnels can only provide mili-second simulations so it is very limited in capacity in testing a design.
That is the very reason why the US has not developed any new physical test facilities except for the final stage testing fascinating the final model to a hyper velocity rocket to see how it respond to the speed comparing it to the simulation.