Abstract: Systems and methods for generating data files for testing computer systems. A base EDI file it provided to a file generating system, preferably by way of a network connection. The file generating system generates a test file by varying at least one parameter of at least one data field contained in the base file, in accordance with a set of instructions. The test file may be saved as part of a test file suite assembled from a number of test files generated by the file generating system. The test file may then be used to test the ability of an EDI system to receive, process or transmit an EDI data file containing the modified data field.