Disclosed is a process to generate and execute relevant, non-redundant test cases starting with an execution trace. An execution trace may be collected. A sequence of actions and the data involved in the actions may then be extracted from the execution trace and persisted separately from one another. Code for a non-deterministic program (“NDP”) may be generated, comprising the sequence of actions but without determining the data. A systematic program analysis of the NDP may be made, exploring possible execution paths and beginning from the path exercised by the persisted data. A new test case may be generated which fixes particular test inputs for the NDP.