Which of the following is NOT considered a material test?

Ductility is indeed a material property, but it does refer to a material's ability to deform under tensile stress, typically measured through various tests. When selecting a characteristic that isn't considered a test in the material assessment context, ductility might seem like it doesn’t fit. However, it is indeed examined through specific tests designed to determine the extent to which a material can deform without breaking.

On the other hand, durability, flammability, and elasticity are also distinct properties of materials, but they fall under broader categories of performance assessments rather than specific tests aimed exclusively at identifying a singular characteristic.

Flammability tests determine how a material reacts to fire, while durability pertains to how well a material withstands wear and tear or various environmental conditions over time. Elasticity involves measuring the material's ability to return to its original shape after deformation.

When considering the definitions and common practices associated with material testing, ductility is typically included as a property tested rather than a separate or broader material assessment. Thus, identifying it as NOT a material test is appropriate in this context.