undertested

Undertested is a term used in software quality assurance to describe areas of a software system that have not been subjected to adequate testing. It can refer to code paths, features, data pipelines, configurations, or environments that have insufficient test coverage, leaving risks of defects and unrevealed failures.

Causes include insufficient test coverage due to time or resource constraints, rapid delivery cycles, high complexity, reliance on manual tests that cannot scale, and gaps in test design such as missing edge cases or untested integrations.

Indicators include low coverage metrics (unit, integration, and end-to-end), high defect leakage into production, unfamiliar or recently changed components, untested input domains, or incidents traceable to untested behavior.

Implications include increased bug risk, potential security vulnerabilities, degraded reliability, and higher maintenance costs. Undertested areas can also obscure performance or scalability issues and erode stakeholder confidence.

Mitigation strategies emphasize risk-based testing, expanding coverage where it matters most, and leveraging automation and observability. Practices include prioritizing tests by risk, using property-based testing and fuzzing for input domains, automated continuous integration, canary releases, and feature flags. Regular risk assessments and code reviews can help identify undertested components early, informing targeted testing and monitoring efforts.