You should see something like this:
<...U-Boot banner...>
- Running 26 driver model tests
+ Running 29 driver model tests
Test: dm_test_autobind
Test: dm_test_autoprobe
Test: dm_test_bus_children
Test: dm_test_gpio
extra-gpios: get_value: error: gpio b5 not reserved
Test: dm_test_gpio_anon
+ Test: dm_test_gpio_copy
+ Test: dm_test_gpio_leak
+ extra-gpios: get_value: error: gpio b5 not reserved
+ Test: dm_test_gpio_requestf
Test: dm_test_leak
Test: dm_test_lifecycle
Test: dm_test_operations