I think it is important to point out to the original poster that there really are two distinct phases to stall testing:
a. Establish the stall handling qualities, which was the original query, for the many configurations and flight conditions required for certification (ie straight, turning, low/high approach rate, sideslip, high power, etc).
b. Establish the stall speeds which are required as the basis for other performance speeds.
This may be far from a straightforward exercise with an aircraft which appears to be stalling at around the maximum speed permitted by the certification standard yet may need handling fixes which could result in an even higher stall speed.