65 lines
2.0 KiB
TypeScript
65 lines
2.0 KiB
TypeScript
 
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/*
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Copyright 2026 Element Creations Ltd.
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SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
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Please see LICENSE in the repository root for full details.
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*/
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import { renderHook } from "@testing-library/react";
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import { describe, expect, test } from "vitest";
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import { useStableValue } from "./useStableValue";
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describe("useStableValue", () => {
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test("keeps the first identity while the contents stay equal", () => {
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const first = { skipLobby: true, fonts: ["Inter"] };
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const { result, rerender } = renderHook(
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({ value }) => useStableValue(value),
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{ initialProps: { value: first } },
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);
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expect(result.current).toBe(first);
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rerender({ value: { skipLobby: true, fonts: ["Inter"] } });
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expect(result.current).toBe(first);
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});
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test("takes the new identity once the contents change", () => {
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const first = { skipLobby: true };
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const second = { skipLobby: false };
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const { result, rerender } = renderHook(
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({ value }) => useStableValue(value),
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{ initialProps: { value: first } },
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);
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rerender({ value: second });
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expect(result.current).toBe(second);
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// And that identity is then the stable one
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rerender({ value: { skipLobby: false } });
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expect(result.current).toBe(second);
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});
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test("handles undefined, for an optional prop left out", () => {
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const { result, rerender } = renderHook(
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({ value }) => useStableValue(value),
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{ initialProps: { value: undefined as { a: number } | undefined } },
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);
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expect(result.current).toBeUndefined();
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const given = { a: 1 };
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rerender({ value: given });
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expect(result.current).toBe(given);
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});
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test("accepts its own notion of equality", () => {
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const first = { id: 1, label: "a" };
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const { result, rerender } = renderHook(
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({ value }) => useStableValue(value, (a, b) => a.id === b.id),
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{ initialProps: { value: first } },
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);
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rerender({ value: { id: 1, label: "b" } });
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expect(result.current).toBe(first);
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});
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});
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