frontend/src/shared/lib/initial-availability.test.tsx

import { act, renderHook } from "@testing-library/react";
import { describe, expect, it, vi } from "vitest";

import { useInitialAvailability } from "./initial-availability";

describe("useInitialAvailability", () => {
	it("keeps loading until content, error, or the initial wait budget", async () => {
		vi.useFakeTimers();

		try {
			const { rerender, result } = renderHook(
				props => useInitialAvailability(props),
				{
					initialProps: {
						hasContent: false,
						identity: "account-a",
						isError: false,
						isFetching: true,
						timeoutMs: 100,
					},
				},
			);

			expect(result.current).toBe("loading");
			await act(() => vi.advanceTimersByTimeAsync(99));
			expect(result.current).toBe("loading");
			await act(() => vi.advanceTimersByTimeAsync(1));
			expect(result.current).toBe("unavailable");

			rerender({
				hasContent: true,
				identity: "account-a",
				isError: false,
				isFetching: false,
				timeoutMs: 100,
			});
			expect(result.current).toBe("ready");
		}
		finally {
			vi.useRealTimers();
		}
	});

	it("does not flash loading during retry for the same identity", async () => {
		vi.useFakeTimers();

		try {
			const { rerender, result } = renderHook(
				props => useInitialAvailability(props),
				{
					initialProps: {
						hasContent: false,
						identity: "account-a",
						isError: true,
						isFetching: false,
					},
				},
			);

			await act(() => vi.runOnlyPendingTimersAsync());
			expect(result.current).toBe("unavailable");
			rerender({
				hasContent: false,
				identity: "account-a",
				isError: false,
				isFetching: true,
			});

			expect(result.current).toBe("unavailable");
		}
		finally {
			vi.useRealTimers();
		}
	});

	it("resets loading only when identity changes", async () => {
		vi.useFakeTimers();

		try {
			const { rerender, result } = renderHook(
				props => useInitialAvailability(props),
				{
					initialProps: {
						hasContent: false,
						identity: "account-a",
						isError: true,
						isFetching: false,
					},
				},
			);

			await act(() => vi.runOnlyPendingTimersAsync());
			expect(result.current).toBe("unavailable");
			rerender({
				hasContent: false,
				identity: "account-b",
				isError: false,
				isFetching: true,
			});

			expect(result.current).toBe("loading");
		}
		finally {
			vi.useRealTimers();
		}
	});
});