A driver might perform correctly in an ideal environment but fail in cases of errors, such as erroneous operations or bad data. Therefore, an important part of driver testing is the testing of the driver's error handling.
All possible error conditions of a driver should be exercised, including error conditions for actual hardware malfunctions. Some hardware error conditions might be difficult to induce, but an effort should be made to force or to simulate such errors if possible. All of these conditions could be encountered in the field. Cables should be removed or be loosened, boards should be removed, and erroneous user application code should be written to test those error paths. See also Chapter 13, Hardening Solaris Drivers.
Be sure to take proper electrical precautions when testing.