add tests for useUpdateEffect

packages/utils/__tests__/use-update-effect.test.ts

@@ -0,0 +1,29 @@
+import { useState } from "react";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { renderHook, cleanupHooks, actHooks } from "@reach-internal/test/utils";
+import { useUpdateEffect } from "@reach/utils";
+
+afterEach(cleanupHooks);
+
+describe("useUpdateEffect", () => {
+	it("should do not call effect on mount", () => {
+		const effect = vi.fn();
+		renderHook(() => useUpdateEffect(effect, []));
+
+		expect(effect).not.toHaveBeenCalled();
+	});
+
+	it("should call effect on every update", () => {
+		const effect = vi.fn();
+		const { result } = renderHook(() => {
+			const [dependency, setDependency] = useState(0);
+			useUpdateEffect(effect, [dependency]);
+			return { setDependency };
+		});
+
+		actHooks(() => result.current.setDependency(10));
+		expect(effect).toHaveBeenCalledTimes(1);
+		actHooks(() => result.current.setDependency(22));
+		expect(effect).toHaveBeenCalledTimes(2);
+	});
+});