1. A method for detecting an error in an interaction between a plurality of software systems, the method comprising: providing information about at least one of at least first and second software systems, and a mapping between at least a portion of said at least first and second software systems; automatically generating a check based upon the information and the mapping; inserting said check into at least one of said first and second software systems; examining said at least one of said first and second software systems and said mapping to determine an error in an interaction between said at least first and second software systems based upon said check; and providing a shadow database in one of said at least first and second software systems, wherein said shadow database contains partial knowledge of the other of said at least first and second software systems and being used to perform a check, and wherein said partial knowledge includes at least one of: partial knowledge of data values in said other of said at least first and second software systems; and partial knowledge of a non-existence of data values in said other of said at least first and second software systems.