1. A computer-implemented method for testing code, the computer-implemented method comprising performing computer-implemented operations for: receiving, at a test engine executing a test application, a new version of the code, the new version of the code comprising a new version of one or more functions; retrieving, by the test engine, an old version of the code from a data storage location, the old version of the code comprising an old version of the one or more functions; comparing, by the test engine, the new version of the code to the old version of the code to determine if the new version of the one or more functions has been modified with respect to the old version of the one or more functions; retrieving, by the test engine, a test summary corresponding to the old version of the one or more functions; in response to determining that the old version of the one or more functions has been modified, treating, by the test engine, the test summary as potentially invalid; generating a logic formula corresponding to the new version of the one or more functions, the logic formula comprising a logic formula that logically describes the behavior of the new version of the one or more functions; and comparing the test summary deemed to be potentially invalid to the logic formula to determine if the test summary deemed to be potentially invalid holds true for the logic formula along all execution paths.