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Oracle-Free Match Testing of a Program Using Covering Arrays and Equivalence Classes

Patent Number: 10,552,300


A process for testing a program includes: receiving a variable comprising a plurality of input values; producing a plurality of equivalence classes for the input values; producing a representative value per equivalence class; producing, by a processor, a primary covering array comprising a plurality of primary vectors; producing a secondary covering array comprising a plurality of secondary vectors; providing the secondary vectors to the program; and producing a result vector comprising a plurality of result entries to test the program. A computer system for testing the program includes: a memory; and a processor, in communication with the memory, wherein the computer system is configured to perform the process for testing the program. A computer program product for testing the program includes: a non-transitory computer readable storage medium readable by a processor and storing program code for execution by the processor to perform the process.

Patent Description

This is a method and software for testing computer software. The method applies to a broad range of software but is particularly applicable software with complex conditions and decision, e.g., process control, avionics, and other areas.  This method also verifies equivalence classes for module unit testing. Both testing and equivalence class verification is achieved using a two-layer covering array which some or all values of a primary covering array represent equivalence classes. A second layer covering array of the equivalence class values is computed, and its values substituted for the equivalence class names in the primary array. It is shown that this method can also detect certain classes of errors without a conventional test oracle.

The program is tested against input values that are partitioned into the equivalence classes. In a particular embodiment, representative values from each equivalence class is provided to the program, and the output the program is stored, e.g., in memory as a result vector. It is contemplated that the program can be executable code (including units, modules, scripts, and the like), data, system configuration files, machine environment state settings, and the like. In a certain embodiment, the program is executable program that receives the representative values as a substitute for the input values of the variable, which is the expected input by the program.


Conventional software testing requires the use of a 'test oracle', i.e., expected results for each set of inputs designated by a test. This invention eliminates the requirement for a test oracle for a significant class of software errors thus reduces cost. It is fully automated, obviating the need for the highest-cost components of testing - human involvement or a mathematical model of the system.

Created January 30, 2021, Updated April 18, 2024