A sample test helper used to acquire resources and automatically tear them down with the upcoming `using` keyword.

sample.test.ts

// This is untested code. More of a proof of concept for what's to come...

async function $acquire<
  Resource
>(fn: () => Promise<readonly [resource: Resource, teadown?: () => void]>) {
  let [resource, teardown = () => {}] = await fn();
  return {
    resource,
    [Symbol.dispose]: teardown,
  }
}

type Database = {
  query(sql: string, ...placeholders: string[]): any[],
  close(): void,
};
async function getTestDatabase(): Promise<Database> {
  return {
    query() { return [] },
    close() {},
  }
}

// Framework-agnostic self-contained tests where resources like databases
// can be setup and destroyed seemlessly. No more beforeEach / afterEach!

it("works like a charm", async () => {
  using {resource: db} = await $acquire(async () => { // ❤️❤️❤️
    let db = await getTestDatabase()
    return [db, () => db.close()]
  })

  let result = db.query("select * from products where id = '?'", "123")
})