What method is used to test and determine the wettability of brazing weld
 

I have never heard of wettability test for brazing welds, only for brazing filler metals, please refer to relevant national standards.Generally, brazing welds are tested for mechanical properties, such as tensile strength and shear strength. X-ray is used to check whether there are welds. For those with strict requirements on air tightness, mass spectrometer or other methods are used to detect air tightness.