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Test Harness

The active otter test harness lives in crates/otter-test and is exposed through the CLI. It discovers JavaScript and TypeScript fixtures, runs each fixture in a fresh runtime, and reports structured outcomes.

Supported suites:

  • engine: first-party engine fixtures under tests/engine;
  • smoke: short release smoke tests under tests/smoke;
  • test262: curated Test262 fixtures under tests/test262-curated.

Each fixture may carry TOML metadata in the source header. The runner uses that metadata for expected exit codes and other fixture-level expectations. When --json is enabled, output is newline-delimited JSON records followed by a summary report using HARNESS_SCHEMA_VERSION.

Discovery skips helper/package directories rather than treating them as standalone tests:

  • directory names starting with _;
  • node_modules.

Use focused suite/filter runs for local iteration, then run the relevant workspace tests before merging harness behavior changes.