Add oxlint and oxfmt

[mmkal]

Summary

Adds oxlint and oxfmt to Captun's local workflow:

• wires format, format:check, lint, lint:check, and lint:fix scripts into package.json
• adds .oxlintrc.json with Captun-scoped ignores, correctness rules, and test-file overrides
• updates the existing code and tests to pass oxlint/oxfmt without changing runtime behavior
• adds oxlint-plugin-captun.js, a local JS plugin with captun/* rules for the project's preferred test style

The custom test rules reject lifecycle hooks, describe wrappers, vi.mock/vi.doMock, helpers declared above tests, and property-level equality checks where toMatchObject is clearer. The rules are scoped to test files through oxlint override globs, so the plugin can grow later without carrying test-file path checks in every rule.

Example

Before:

import { afterEach, beforeEach, describe, expect, test } from "vitest";

let server: Awaited<ReturnType<typeof startServer>>;

describe("weather API", () => {
  beforeEach(async () => {
    server = await startServer({ fixtures: ["rain"] });
  });

  afterEach(async () => {
    await shutDownServer(server);
  });

  test("returns the current forecast", async () => {
    const response = await fetchWeather(server.url, "london");

    expect(response.status).toBe(200);
  });
});

After:

import { expect, test } from "vitest";

test("weather API returns the current forecast", async () => {
  await using server = await startServerFixture({ fixtures: ["rain"] });

  const response = await fetchWeather(server.url, "london");

  expect(response).toMatchObject({ status: 200 });
});

async function startServerFixture(options: { fixtures: string[] }) {
  const server = await startServer(options);
  return {
    url: server.url,
    async [Symbol.asyncDispose]() {
      await shutDownServer(server);
    },
  };
}

Verification

• pnpm run check
• pnpm test

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/captun@5

commit: 510e916

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