Efficient and flexible GUI test execution via test merging

As a test suite evolves, it can accumulate redundant tests. To address this problem, many test-suite reduction techniques, based on different measures of redundancy, have been developed. A more subtle problem, that can also cause test-suite bloat and that has not been addressed by existing research, is the accumulation of similar tests. Similar tests are not redundant by any measure; but, they contain many common actions that are executed repeatedly, which over a large test suite, can degrade execution time substantially.

We present a test merging technique for GUI tests. Given a test suite, the technique identifies the tests that can be merged and creates a merged test, which covers all the application states that are exercised individually by the tests, but with the redundant common steps executed only once. The key novelty in the merging technique is that it compares the dynamic states induced by the tests to identify a semantically meaningful interleaving of steps from different tests. The technique not only improves the efficiency of test execution, but also ensures that there is no loss in the fault-revealing power of the original tests. In the empirical studies, conducted using four open-source web applications and one proprietary enterprise web application, in which over $3300$ test cases and 19600 test steps were analyzed, the technique reduced the number of test steps by 29% and the test-execution time by 39%.