Beyond LLM-based test automation: A Zero-Cost Self-Healing Approach Using DOM Accessibility Tree Extraction

Abstract: Modern web test automation frameworks rely heavily on CSS selectors, XPath expressions, and visible text labels to locate UI elements. These locators are inherently brittle -- when web applications update their DOM structure or class names, test suites fail at scale. Existing self-healing approaches increasingly delegate element discovery to LLMs, introducing per-run API costs that become prohibitive at enterprise scale. This paper presents a zero-cost self-healing test automation framework that replaces LLM-based discovery with a structured accessibility tree extraction algorithm. The framework employs a ten-tier priority-ranked locator hierarchy -- get_by_role (W3C standard), data-testid, ARIA labels, CSS class fragments, visible text -- to discover robust selectors from a live DOM in a single one-time pass. A self-healing mechanism re-extracts only broken selectors upon failure, rather than re-running full discovery. The framework is validated against automationexercise.com across three device profiles (Desktop Chrome, Desktop Safari, iPhone 15) and ten business process test workflows under a three-tier hierarchy (L0: Domain, L1: Process, L2: Feature). Results demonstrate a 31/31 (100%) pass rate across 31 test combinations with total execution time of 22 seconds under parallel execution. Self-healing is empirically demonstrated: a stale selector is detected and re-discovered in under 1 second with zero human intervention. The framework scales to 300+ test cases with zero ongoing API cost.