How to use the TestClock in a test calls a function that uses its own ManagedRuntime (repro linked)

it.effect("mytest", () => Effect.gen(function* () {
  const runtime = yield* Effect.runtime()
  
  const adjustTestClock = (duration: Duration.DurationInput) =>
    Effect.gen(function* () {
      return yield* Effect.promise(() =>
        Runtime.runPromise(runtime)(TestClock.adjust(duration)),
      )
    })
  
  // this function is called from within another ManagedRuntime
  handlerFnMock.mockImplementation(() =>
    Effect.gen(function* () {
      yield* adjustTestClock(FUNCTION_RUNTIME)
    }),
  )
}))