Test Runner II

Requirements

• Export TestRunner as named and default. Keep test(name, callback), skip(name), and async run() from Test Runner. Add describe(name, declare), which invokes a synchronous declaration callback with this runner. Registration methods return this for chaining. Names must be nonempty strings after trimming; preserve their original text, and allow duplicates.
• Suites may nest. Each test result name consists of its suite names followed by its test name, joined with > and one space on each side. Root test names remain unchanged. Suites themselves do not create results. Restore the parent registration scope after describe finishes.
• Invalid names/callbacks throw TypeError. If a suite declaration throws, remove all tests registered by that describe call and restore the parent scope; rethrow the same error. A declaration returning a thenable throws TypeError and rolls back. Async suite declarations are unsupported; do not schedule later registrations from them.
• run returns Promise<{ total, passed, failed, skipped, results }>. Results have name and status: passed, failed, or skipped. Only failed results have an own error property containing the exact thrown/rejected value, including undefined. Skipped tests invoke no callbacks.
• Execute active tests serially in registration order, awaiting returned values/thenables. One failure does not stop later tests. Snapshot registrations at run start; later registrations affect future runs only. Each run executes the full snapshot again and returns fresh objects.
• Reject overlapping run calls on the same runner with Error without disturbing the active run. Independent runners may run concurrently. Release the running flag even after failures. No test library, timeouts, parallel test scheduling, retries, durations, or assertion implementation is required.
• Lifecycle hooks are outside scope for this version; Test Runner III adds them.

Examples

Input: const r = new TestRunner(); r.describe("math", s => { s.test("sum", () => 3); s.describe("edge", n => n.skip("empty")); }); await r.run();
Output: Results: math > sum passed; math > edge > empty skipped.

Input: r.describe("bad", s => { s.test("discard", () => 1); throw new Error("stop"); });
Output: Throws; the entire bad suite’s registrations are discarded.