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import React, { memo, useContext } from 'react';
import { fireEvent, pureRender } from '../../../tests/utils';
import Anchor from '../Anchor';
import AnchorContext from '../context';
let innerCount = 0;
let outerCount = 0;
const handleClick = () => {
outerCount++;
};
// we use'memo' here in order to only render inner component while context changed.
const CacheInner: React.FC = memo(() => {
innerCount++;
// subscribe locale context
useContext(AnchorContext);
return null;
});
const CacheOuter: React.FC = memo(() => (
<>
<button type="button" onClick={handleClick} id="parent_btn">
Click
</button>
<Anchor affix={false}>
<CacheInner />
</Anchor>
</>
));
it("Rendering on Anchor without changed won't trigger rendering on child component.", () => {
const { container, unmount } = pureRender(<CacheOuter />);
expect(outerCount).toBe(0);
expect(innerCount).toBe(2);
fireEvent.click(container.querySelector('#parent_btn')!);
expect(outerCount).toBe(1);
expect(innerCount).toBe(2);
unmount();
});
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