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48 lines
1.3 KiB
48 lines
1.3 KiB
import React, { memo, useRef, useState, useContext } from 'react';
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import { mount } from 'enzyme';
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import Row from '../row';
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import RowContext from '../RowContext';
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const CacheInner = memo(() => {
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const countRef = useRef(0);
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countRef.current++;
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useContext(RowContext);
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return (
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<div>
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Child Rendering Count: <span id="child_count">{countRef.current}</span>
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</div>
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);
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});
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const CacheOuter = () => {
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const [count, setCount] = useState(1);
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const handleClick = () => {
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setCount(count + 1);
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};
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return (
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<div>
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<button type="button" onClick={handleClick} id="parent_btn">
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Click
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</button>
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Parent Rendering Count: <span id="parent_count">{count}</span>
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<Row>
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<CacheInner />
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</Row>
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</div>
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);
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};
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it('Cached RowContext is working', () => {
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const wrapper = mount(<CacheOuter />);
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const childCount = wrapper.find('#child_count').text();
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wrapper.find('#parent_btn').at(0).simulate('click');
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expect(wrapper.find('#parent_count').text()).toBe('2');
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// child component won't rerender
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expect(wrapper.find('#child_count').text()).toBe(childCount);
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wrapper.find('#parent_btn').at(0).simulate('click');
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expect(wrapper.find('#parent_count').text()).toBe('3');
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// child component won't rerender
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expect(wrapper.find('#child_count').text()).toBe(childCount);
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});
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