58 lines
1.6 KiB
JavaScript
58 lines
1.6 KiB
JavaScript
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/**
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* External dependencies
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*/
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import TestRenderer, { act } from 'react-test-renderer';
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/**
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* Internal dependencies
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*/
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import { usePrevious } from '../use-previous';
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describe( 'usePrevious', () => {
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const TestComponent = ( { testValue } ) => {
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const previousValue = usePrevious( testValue );
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return <div testValue={ testValue } previousValue={ previousValue } />;
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};
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let renderer;
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beforeEach( () => ( renderer = null ) );
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it( 'should be undefined at first pass', () => {
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act( () => {
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renderer = TestRenderer.create( <TestComponent testValue={ 1 } /> );
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} );
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const testValue = renderer.root.findByType( 'div' ).props.testValue;
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const testPreviousValue = renderer.root.findByType( 'div' ).props
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.previousValue;
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expect( testValue ).toBe( 1 );
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expect( testPreviousValue ).toBe( undefined );
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} );
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it( 'test new and previous value', () => {
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let testValue;
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let testPreviousValue;
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act( () => {
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renderer = TestRenderer.create( <TestComponent testValue={ 1 } /> );
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} );
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act( () => {
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renderer.update( <TestComponent testValue={ 2 } /> );
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} );
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testValue = renderer.root.findByType( 'div' ).props.testValue;
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testPreviousValue = renderer.root.findByType( 'div' ).props
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.previousValue;
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expect( testValue ).toBe( 2 );
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expect( testPreviousValue ).toBe( 1 );
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act( () => {
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renderer.update( <TestComponent testValue={ 3 } /> );
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} );
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testValue = renderer.root.findByType( 'div' ).props.testValue;
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testPreviousValue = renderer.root.findByType( 'div' ).props
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.previousValue;
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expect( testValue ).toBe( 3 );
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expect( testPreviousValue ).toBe( 2 );
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} );
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} );
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