Even assuming exhaustive tests at component level, interaction faults can only be avoided by thorough testing of component interfaces during integration testing. In view of the relevance of the integration testing phase for modern componentübased systems, this article presents an extensive set of interface coverage criteria, which are not restricted to mere operation call sequences, but include messageübased as well as stateübased information. In order to support rational decisionümaking in identifying the best affordable integration coverage criterion for a given industrial system, a tool was implemented providing conservative estimates of the testing effort expected to be required by a given stateübased integration testing strategy considered, supporting in addition the automatic visualisation of the interface entities needed to be covered.