Testing from first-order specifications has mainly been studied for flat specifications, that are specifications of a single software module. However, the specifications of large software systems are generally built out of small specifications of individual modules, by enriching their union. The aim of integration testing is to test the composition of modules assuming that they have previously been verified, i.e. assuming their correctness. One of the main method for the selection of test cases from first-order specifications, called axiom unfolding, is based on a proof search for the different instances of the property to be tested, thus allowing the coverage of this property. The idea here is to use deduction modulo as a proof system for structured first-order specifications in the context of integration testing, so as to take advantage of the knowledge of the correctness of the individual modules.