Integration testing allows us to verify that the interfacing systems interact and communicate between them as defined in the Interface Control Document (ICD)
Integration testing is done during the Systems Interface Test (SIT) and the Master Integration Testing (MIT) phases of the Project. During Systems Interface Testing, interface pairs are tested to verify their conformance to the ICD. During Master Integration Testing, the Systems are grouped by their function and tested to specific business operational scenarios to verify that they are ready to support live banking operations.
This is an independent verification and validation exercise involving all interfacing systems. Multiple test cycles, including regression testing, may be necessary before a system pair or a group of systems exit the Test phase.