The pull/stretch test on wet hair is used mainly to assess:

Gently stretching a wet strand to see how far it extends and whether it returns is a way to assess elasticity. Healthy hair with good elasticity stretches and recoils; weak hair may stretch and break or fail to return, signaling damage. Because chemical services stress the hair, poor elasticity is a caution sign. The wet stretch test is a quick practical check that supports the hair analysis. Knowing which characteristic this test measures (elasticity) is the kind of applied detail the exam includes.