The phrase "knife test" means using a knife to check the sharpness or quality of something, like cutting through an object to see how easily it goes through.
Sentences with «knife test»
The Aqua Lung Big Squeeze Titanium dive knife was a ScubaLab Testers Choice during the 2018 dive knife test. (scubadiving.com)
We went off to dinner and when we got home I checked it and did the knife test. (orangette.net)
Pour into a greased pan (I used my 8 ″ round spring form pan because that's the only pan I've got, but I'm sure a standard loaf pan would work fine) and bake for 40 minutes or until passes the clean knife test. (jenncuisine.com)