selftests

Self-tests are automated checks conducted by a system on itself to verify basic operation, integrity, and readiness for normal use. They are embedded in hardware and software and can run at power-on, periodically, or in response to events. In hardware engineering, self-tests are often called built-in self-test (BIST) or power-on self-test (POST). They exercise subsystems such as memory, processors, interconnects, and peripherals, using test patterns, parity checks, or diagnostic algorithms, and report results via codes, LEDs, or management interfaces. They may be mandatory for safety-critical equipment and serve as a first line of fault detection and maintenance.

In software, self-tests refer to self-diagnostic routines, lightweight unit tests, or health checks that verify components function as expected. They can run during startup, on a schedule, or in response to events, and typically report status to logs, monitoring dashboards, or alerting systems. They are often integrated with the build or runtime environment and are especially common in reliability- or safety-critical systems.

In medical devices and other regulated equipment, self-tests verify critical subsystems such as sensors, power sources, and communication interfaces before use. They help detect conditions that could compromise operation, but they do not replace external calibration, validation, or formal testing procedures.

Design considerations and limitations: self-tests aim to detect faults quickly with minimal overhead, but coverage is not complete and some faults only appear under real-world conditions or stress. Results can be inconclusive or require escalation to full diagnostics or maintenance procedures.