Described herein are methods and apparatus for testing bond strength of a chemical-sealant, lost circulation material to a subterranean sample. An apparatus can include a body defining walls of a chamber to receive a subterranean core sample from a wellbore, the body being sized to receive a chemical-sealant lost-circulation material (CS-LCM) to an area of the chamber between the core sample and the body, and a removable insert mateable to the body, the insert defining a base of the chamber, where the test apparatus is positionable to transfer a force to the core sample to decouple the core sample from the CS-LCM such that a shear bond strength of the CS-LCM to the core sample is determinable based on a maximum amount of force used to decouple the core sample from the CS-LCM.