Software architectures can play a role in improving the testing process of complex systems. In particular descriptions of the software architecture can be useful to drive integration testing, since they supply information about how the software is structured in parts and how those parts (are expected to) interact. We propose to use formal architectural descriptions to model the "interesting" behaviour of the system. This model is at a right level of abstraction to be used as a formal base on which integration test strategies can be devised. Starting from a formal description of the software architecture (given in the CHAM formalism), we first derive a graph of all the possible behaviours of the system in terms of the interactions between its components. This graph contains altogether the information we need for the planning of integration testing. On this comprehensive model, we then identify a suitable set of reduced graphs, each highlighting specific architectural properties of the system. These reduced graphs can be used for the generation of integration tests according to a coverage strategy, analogously to what happens with the control and data flow graphs in unit testing.