This paper demonstrates the advantages of the switching test circuit "double source test" (DST) on reliability and robustness tests on GaN HEMTs. This circuit performs switching tests with an auxiliary switch to shortcircuit the DUT while on stand-by, allowing to control of the duration of the drain-source static stress over the DUT. This feature can contribute to the study of the impact of hard switching events on the current collapse of GaN HEMTs independently of the static drain-source stress, when the tests reported in present literature show these effects superposed. Moreover, the DST when programmed for minimum drain-source stress considerably reduced the current collapse on p-GaN gate devices, allowing longer repetitive tests.