In the langgraph checkpoint test we compare

expect(cpDoc!.upserted_at.getTime()).toBeGreaterThanOrEqual(
  before.getTime()
);

But on fast machine (we normally run these tests locally) this is not always true and the difference in 1-2ms makes this test fail. Easiest solution would be to add some tolerance (i.e. "within 10ms").

https://github.com/langchain-ai/langgraphjs/blob/main/libs/checkpoint-mongodb/src/tests/checkpoints.int.test.ts#L189-L191