Tensor codes provide a simple family of combinatorial constructions of locally testable codes that generalize the family of Reed-Muller codes. The natural test for tensor codes, the axis-parallel line vs. point test, plays an essential role in constructions of probabilistically checkable proofs. The quantum soundness of tensor code test is an essential component of the MIP* = RE theorem as it naturally generalize the low indivitual degree test. In this talk, we will discuss the proof ideas behind the quantum soundness analysis, its use in the MIP* = RE proof, and several interesting related open problems.