import { describe, expect, it } from "vitest"; import { AUTO_SCROLL_BOTTOM_EPSILON_PX, isScrollContainerAtBottom } from "./chat-scroll"; describe("isScrollContainerAtBottom", () => {  it("returns true when already at bottom", () => {    expect(      isScrollContainerAtBottom({        scrollTop: 600,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(true);  });   it("returns true when within the bottom epsilon", () => {    expect(      isScrollContainerAtBottom({        scrollTop: 599,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(true);  });   it("returns false when the user is above the epsilon", () => {    expect(      isScrollContainerAtBottom({        scrollTop: 597,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(false);  });   it("clamps negative epsilons to zero", () => {    expect(      isScrollContainerAtBottom(        {          scrollTop: 599,          clientHeight: 400,          scrollHeight: 1_000,        },        -1,      ),    ).toBe(false);  });   it("falls back to the default epsilon for non-finite values", () => {    expect(      isScrollContainerAtBottom(        {          scrollTop: 599,          clientHeight: 400,          scrollHeight: 1_000,        },        Number.NaN,      ),    ).toBe(true);    expect(AUTO_SCROLL_BOTTOM_EPSILON_PX).toBe(2);  });   it("treats overscrolled values as bottom", () => {    expect(      isScrollContainerAtBottom({        scrollTop: 610,        clientHeight: 400,        scrollHeight: 1_000,      }),    ).toBe(true);  });});