selftest

Self-test, or selftest, is a procedure in which a system or component assesses its own operation to verify readiness and detect faults. It is performed without external testing equipment, relying on internal sensors, test patterns, or built-in routines. Self-tests are used in hardware devices, software systems, and various medical and consumer applications to improve reliability and safety.

In hardware, self-tests are often called built-in self-test (BIST) or power-on self-test (POST). During startup or at defined intervals, the device runs checks on memory, processors, buses, and critical peripherals, reporting results through status codes, LEDs, or a user interface. These tests aim to identify faults early and prevent malfunction.

Software self-tests include health checks and self-diagnostic routines that run inside applications, firmware, or operating systems. They may validate configuration, resource availability, and data integrity, and can trigger recovery actions or alerts. In development, unit tests and automated test suites serve a related role by validating code behavior under predefined conditions.

Medical devices, automotive systems, and consumer electronics commonly implement self-tests to ensure safe operation, for example battery health checks, sensor calibration, and fault isolation. The scope and depth of self-test capability vary by application, with more critical systems demanding more rigorous coverage.

Limitations of self-tests include incomplete fault coverage, false positives or negatives, and potential disruption to normal operation. Effective use requires careful design, clear reporting, and occasional external verification. Self-testing is often complemented by ongoing diagnostics, monitoring, and maintenance programs.

See also built-in self-test, POST, self-diagnostic, health monitoring.