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A test case specifies conditions, inputs, an operation to perform and the expected result or acceptance property for software testing. Its test oracle must distinguish success from failure.^[ref] Merely executing a computer program without checking an outcome supplies weaker evidence.

For example, a sorting algorithm given 3,1,3 should return 1,3,3. A stronger test oracle checks both sortedness and preservation of the input multiset; checking only sortedness would accept an empty result. The test case also needs a policy for equal elements if their original order matters. Explicit preconditions and expected outcomes make a failure reproducible and help a later reader understand which contract the test case exercises.