This test calls `mock()` directly but isn't wrapped in `if (isBun)`, so it will throw `TypeError: mock is not a function` when this file is run under Jest or Vitest (where `test-interop.js` returns `mock: null`). Since the behavior being tested is meant to match Jest semantics anyway, the simplest fix is to use `jest.fn(...)` instead of `mock(...)` here — they're the same function under Bun and the assertions would then exercise the cross-runner contract this file is documented to support.