feat(test): add retry and repeats options to Deno.test (#35053)
Migrating a test suite from a third-party runner like Vitest to `deno
test` is harder than it should be, partly because there's no built-in way to
tolerate or surface flaky tests. This adds two per-test options that
mirror Vitest's semantics: `retry` re-runs a failing test and passes if any
attempt passes, while `repeats` runs the test several times and requires every
run to pass. They compose, so each repetition may itself be retried. Matching
`--retry` and `--repeats` flags set a default for the whole run; a test
that sets its own option takes precedence, including an explicit `0` that
opts the test out of a flag-provided default.
The runner already drives one JS call per test from Rust, so this wraps
that call in an attempt/repetition loop. Each attempt re-runs the beforeEach
and afterEach hooks and captures a fresh sanitizer baseline, which keeps
every attempt's leak check independent and makes a resource leak retryable
like any other failure. A failed-but-retried attempt is surfaced through a new
informational event so the reporter can print it, and a test that
ultimately passes after a retry is counted as `flaky` in the summary line. Hook
errors and uncaught errors are intentionally not retried.
A couple of limitations worth calling out: there is no `deno.json`
configuration for retry/repeats yet (CLI flag and per-test option only);
and the `junit` and `tap` reporters don't yet treat retried attempts
specially, so a retried test re-registers its steps under fresh ids and emits
duplicate `<testcase>`/step entries in those reporters (the pretty and dot
reporters drop the discarded attempts). When a test with steps passes on a later
attempt, the final attempt's passing steps are counted but not
re-printed individually (the earlier failed attempt's steps are still shown). None
of these affect correctness of the pass/fail verdict or the flaky count.
Closes https://github.com/denoland/deno/issues/19882
