If you're using Rust with DriverTestRealm we heavily recommend that you use RealmBuilder to set up a new component per test instance (See example).
This will make each test case hermetic and will be a better experience.
Rust tests are each run in their own sub-process, meaning each test runs at the same time. Using the Simple example, there is only one DriverTestRealm component. The test author has to be very careful not to Set/Check data on the same driver across different tests, otherwise there will likely be data races.