Suspending the machine, shutting down, powering off or external usb disks, will aborts the tests and must be restarted.
maybe some spezial drives will retain the test progress which depends on the disk firmware, controller behavior, and power state handling but the most consumer drives will aborts and restart but i don't think so.
When a smartctl command is issued, its effects persist until explicitly changed or until the system is powered off. If the system is powered off, the drive will retain the state set by the smartctl command when it was last used. This means that any ongoing test or command will be interrupted and need to be restarted after power is restored.
Does SMART extended test continue after power down and restart on the next day?
The bare minimum smartctl command to check disk health If you frequently suspend/shut down, consider running short tests more often, as they complete faster (minutes instead of hours).
Short: runs tests that have a high probability of detecting device problems
Use cron to run tests at times when the system is unlikely to be suspended/shut down, etc., so schedule tests for times when the system is stable, and check logs afterward to ensure completion