58 lines
1.8 KiB
TypeScript
58 lines
1.8 KiB
TypeScript
// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
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// See LICENSE.txt for license information.
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import {renderHook, act} from '@testing-library/react-native';
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import useInitialValue from './initial_value';
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describe('useInitialValue', () => {
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test('should return the value from the factory on first render', () => {
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const factory = jest.fn(() => 42);
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const {result} = renderHook(() => useInitialValue(factory));
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expect(factory).toHaveBeenCalledTimes(1);
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expect(result.current).toBe(42);
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});
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test('should call factory only once and keep same value on re-renders', () => {
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let callCount = 0;
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const factory = jest.fn(() => {
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callCount += 1;
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return callCount;
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});
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const {result, rerender} = renderHook(() => useInitialValue(factory));
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expect(factory).toHaveBeenCalledTimes(1);
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expect(result.current).toBe(1);
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act(() => {
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rerender(undefined);
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});
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expect(factory).toHaveBeenCalledTimes(1);
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expect(result.current).toBe(1);
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act(() => {
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rerender(undefined);
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});
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expect(factory).toHaveBeenCalledTimes(1);
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expect(result.current).toBe(1);
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});
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test('should work with object values', () => {
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const initial = {id: 1, name: 'test'};
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const factory = jest.fn(() => initial);
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const {result} = renderHook(() => useInitialValue(factory));
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expect(result.current).toEqual(initial);
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expect(result.current).toBe(initial);
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});
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test('should work with string values', () => {
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const factory = jest.fn(() => 'hello');
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const {result} = renderHook(() => useInitialValue(factory));
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expect(result.current).toBe('hello');
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});
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});
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