bun.sh/test/regression/issue/test-process-stdout-async-iterator.test.ts

import { expect, test } from "bun:test";

test("process.stdout and process.stderr have Symbol.asyncIterator for Node.js compatibility", () => {
  // This is needed for compatibility with tools like execa that check for async iterability
  // to determine stream capabilities
  expect(typeof process.stdout[Symbol.asyncIterator]).toBe("function");
  expect(typeof process.stderr[Symbol.asyncIterator]).toBe("function");
});

test("process.stdout and process.stderr async iterators work without throwing", async () => {
  // The iterators should work even though stdout/stderr are write-only
  // They should just complete immediately without yielding any values
  const stdoutIterator = process.stdout[Symbol.asyncIterator]();
  const stdoutResult = await stdoutIterator.next();
  expect(stdoutResult.done).toBe(true);
  expect(stdoutResult.value).toBeUndefined();

  const stderrIterator = process.stderr[Symbol.asyncIterator]();
  const stderrResult = await stderrIterator.next();
  expect(stderrResult.done).toBe(true);
  expect(stderrResult.value).toBeUndefined();
});

test("tty.WriteStream has Symbol.asyncIterator", () => {
  const tty = require("node:tty");
  // Create a WriteStream for stdout fd
  const stream = new tty.WriteStream(1);
  expect(typeof stream[Symbol.asyncIterator]).toBe("function");
});