Test authoring

Read applicable AGENTS.md and their declared adapter alias, otherwise .agents/skills/test-authoring/SKILL.md from the repository root if present. Local policy overrides these defaults; do not reload an already-read adapter or canonical skill.

Use the repository's test conventions and the matching runner skill.

• Test observable behavior, boundary failures, and regressions. Do not test implementation details.
• Build fixtures through public constructors or documented helpers. Keep data minimal, explicit, and representative.
• Add a focused failing test before a behavior change when that behavior can be tested. Then run the narrowest relevant test and the required checks.
• Read core practice before choosing a runner-specific approach.
• Read tautological tests before finishing a test whose assertion is not obviously falsifiable by a defect in the code under test.
• Read dependency boundaries before asserting on anything a dependency produces, and whenever a dependency upgrade breaks a test.

Consumer wrapper owns: project test commands, coverage targets, mock libraries, and integration environments.