import { describe, expect, it } from "vitest"; import { AUTO_SCROLL_BOTTOM_THRESHOLD_PX, isScrollContainerNearBottom } from "./chat-scroll"; describe("isScrollContainerNearBottom", () => {  it("returns true when already at bottom", () => {    expect(      isScrollContainerNearBottom({        scrollTop: 600,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(true);  });   it("returns true when within the auto-scroll threshold", () => {    expect(      isScrollContainerNearBottom({        scrollTop: 540,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(true);  });   it("returns false when the user is meaningfully above the bottom", () => {    expect(      isScrollContainerNearBottom({        scrollTop: 520,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(false);  });   it("clamps negative thresholds to zero", () => {    expect(      isScrollContainerNearBottom(        {          scrollTop: 539,          clientHeight: 400,          scrollHeight: 1_000,        },        -1,      ),    ).toBe(false);  });   it("falls back to the default threshold for non-finite values", () => {    expect(      isScrollContainerNearBottom(        {          scrollTop: 540,          clientHeight: 400,          scrollHeight: 1_000,        },        Number.NaN,      ),    ).toBe(true);    expect(AUTO_SCROLL_BOTTOM_THRESHOLD_PX).toBe(64);  });});