1. A method for providing a test case for a modified program, comprising: obtaining a modification item that makes modification on a previous version of the program; locating the modification item after a first instrument and before a second instrument of a plurality of instruments inserted into the program; obtaining an execution path of the modified program that is between the first instrument and the second instrument and associated with the modification as well as a constraint set corresponding to the execution path; obtaining an execution result, outputted by the first instrument, of executing the previous version of the program using an original test case; and determining a test case applicable for the execution path based on the execution result and the constraint set.