Fix bug - FlatList component did not render more items when content was filtered
Summary: **Bug Description** The FlatList component receives content items via the data prop, and renders an initial number of items on the app's view. When a user scrolls to the end of the list, the component will append and render more available items at the end of the list. There was a bug where when the content was filtered, there were more available items but the component did not append/render them. This is due to the current appending/rendering logic in VirtualizedList, which does not account for data changes as a condition for updating/rendering. VirtualizedList is a dependency of FlatList, so this issue affects FlatList as well. **Approach to Fixing Bug** (i) Reproduce bug on iOS view of FlatList. (ii) For VirtualizedList component: # Isolate onEndReached function that appends more data to component UI. # Isolate _onContentSizeChange function that is called when list content changes. # Write snapshot tests using jest, based off existing test for FlatList. # Refactor logic to append more data to list into _maybeCallOnEndReached function. # Call _maybeCallOnEndReached in both _onContentSizeChange and _onScroll. (iii) Run snapshot tests and observe jest output. (iv) Bring up iOS view of FlatList and check that component now renders more items when content is filtered. Many thanks to sahrens for guidance in developing this code! Reviewed By: sahrens Differential Revision: D4877388 fbshipit-source-id: c10c9eef1912f491450a62b81a9bc41f7f784203
This commit is contained in:
Tony Tan
Facebook Github Bot
parent
ff056d22d9
commit
3e7aa5f14e
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@ -623,12 +623,29 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
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return !this.props.horizontal ? metrics.y : metrics.x;
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}
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_maybeCallOnEndReached() {
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const {data, getItemCount, onEndReached, onEndReachedThreshold} = this.props;
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const {contentLength, visibleLength, offset} = this._scrollMetrics;
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const distanceFromEnd = contentLength - visibleLength - offset;
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if (onEndReached &&
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this.state.last === getItemCount(data) - 1 &&
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distanceFromEnd < onEndReachedThreshold * visibleLength &&
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(this._hasDataChangedSinceEndReached ||
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this._scrollMetrics.contentLength !== this._sentEndForContentLength)) {
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// Only call onEndReached once for a given dataset + content length.
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this._hasDataChangedSinceEndReached = false;
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this._sentEndForContentLength = this._scrollMetrics.contentLength;
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onEndReached({distanceFromEnd});
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}
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}
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_onContentSizeChange = (width: number, height: number) => {
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if (this.props.onContentSizeChange) {
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this.props.onContentSizeChange(width, height);
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}
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this._scrollMetrics.contentLength = this._selectLength({height, width});
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this._updateCellsToRenderBatcher.schedule();
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this._maybeCallOnEndReached();
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};
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_sampleFillRate(sampleType: string) {
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@ -662,7 +679,7 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
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const dOffset = offset - this._scrollMetrics.offset;
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const velocity = dOffset / dt;
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this._scrollMetrics = {contentLength, dt, offset, timestamp, velocity, visibleLength};
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const {data, getItemCount, onEndReached, onEndReachedThreshold, windowSize} = this.props;
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const {data, getItemCount, windowSize} = this.props;
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this._sampleFillRate('onScroll');
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@ -670,19 +687,10 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
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if (!data) {
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return;
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}
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const distanceFromEnd = contentLength - visibleLength - offset;
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const itemCount = getItemCount(data);
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if (onEndReached &&
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this.state.last === itemCount - 1 &&
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distanceFromEnd < onEndReachedThreshold * visibleLength &&
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(this._hasDataChangedSinceEndReached ||
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this._scrollMetrics.contentLength !== this._sentEndForContentLength)) {
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// Only call onEndReached once for a given dataset + content length.
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this._hasDataChangedSinceEndReached = false;
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this._sentEndForContentLength = this._scrollMetrics.contentLength;
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onEndReached({distanceFromEnd});
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}
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this._maybeCallOnEndReached();
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const {first, last} = this.state;
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const itemCount = getItemCount(data);
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if ((first > 0 && velocity < 0) || (last < itemCount - 1 && velocity > 0)) {
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const distanceToContentEdge = Math.min(
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Math.abs(this._getFrameMetricsApprox(first).offset - offset),
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@ -0,0 +1,80 @@
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/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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'use strict';
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jest.disableAutomock();
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const React = require('React');
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const ReactTestRenderer = require('react-test-renderer');
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const VirtualizedList = require('VirtualizedList');
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describe('VirtualizedList', () => {
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it('renders simple list', () => {
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const component = ReactTestRenderer.create(
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<VirtualizedList
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data={[{key: 'i1'}, {key: 'i2'}, {key: 'i3'}]}
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renderItem={({item}) => <item value={item.key} />}
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/>
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);
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expect(component).toMatchSnapshot();
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});
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it('renders empty list', () => {
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const component = ReactTestRenderer.create(
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<VirtualizedList
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data={[]}
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renderItem={({item}) => <item value={item.key} />}
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/>
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);
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expect(component).toMatchSnapshot();
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});
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it('renders null list', () => {
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const component = ReactTestRenderer.create(
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<VirtualizedList
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data={undefined}
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renderItem={({item}) => <item value={item.key} />}
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/>
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);
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expect(component).toMatchSnapshot();
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});
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it('renders all the bells and whistles', () => {
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const component = ReactTestRenderer.create(
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<VirtualizedList
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ItemSeparatorComponent={() => <separator />}
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ListFooterComponent={() => <footer />}
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ListHeaderComponent={() => <header />}
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data={new Array(5).fill().map((_, ii) => ({id: String(ii)}))}
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keyExtractor={(item, index) => item.id}
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getItemLayout={({index}) => ({length: 50, offset: index * 50})}
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numColumns={2}
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refreshing={false}
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onRefresh={jest.fn()}
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renderItem={({item}) => <item value={item.id} />}
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/>
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);
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expect(component).toMatchSnapshot();
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});
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it('test getItem functionality where data is not an Array', () => {
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const component = ReactTestRenderer.create(
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<VirtualizedList
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data={new Map([['id_0', {key: 'item_0'}]])}
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getItem={(data, index) => data.get('id_' + index)}
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getItemCount={(data: Map) => data.size}
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renderItem={({item}) => <item value={item.key} />}
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/>
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);
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expect(component).toMatchSnapshot();
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});
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});
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@ -0,0 +1,261 @@
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// Jest Snapshot v1, https://goo.gl/fbAQLP
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exports[`VirtualizedList renders all the bells and whistles 1`] = `
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<RCTScrollView
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ItemSeparatorComponent={[Function]}
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ListFooterComponent={[Function]}
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ListHeaderComponent={[Function]}
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data={
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Array [
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Object {
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"id": "0",
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},
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Object {
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"id": "1",
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},
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Object {
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"id": "2",
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},
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Object {
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"id": "3",
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},
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Object {
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"id": "4",
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},
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]
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}
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disableVirtualization={false}
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getItem={[Function]}
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getItemCount={[Function]}
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getItemLayout={[Function]}
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horizontal={false}
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initialNumToRender={10}
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keyExtractor={[Function]}
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maxToRenderPerBatch={10}
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numColumns={2}
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onContentSizeChange={[Function]}
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onEndReachedThreshold={2}
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onLayout={[Function]}
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onRefresh={[Function]}
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onScroll={[Function]}
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onScrollBeginDrag={[Function]}
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refreshControl={
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<RefreshControlMock
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onRefresh={[Function]}
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refreshing={false}
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/>
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}
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refreshing={false}
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renderItem={[Function]}
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renderScrollComponent={[Function]}
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scrollEventThrottle={50}
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stickyHeaderIndices={Array []}
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updateCellsBatchingPeriod={50}
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windowSize={21}
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>
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<RCTRefreshControl />
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<View>
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<View
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onLayout={[Function]}
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>
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<header />
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</View>
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<View
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onLayout={undefined}
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>
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<item
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value="0"
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/>
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<separator />
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</View>
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<View
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onLayout={undefined}
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>
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<item
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value="1"
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/>
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<separator />
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</View>
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<View
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onLayout={undefined}
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>
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<item
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value="2"
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/>
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<separator />
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</View>
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<View
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onLayout={undefined}
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>
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<item
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value="3"
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/>
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<separator />
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</View>
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<View
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onLayout={undefined}
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>
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<item
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value="4"
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/>
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</View>
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<View
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onLayout={[Function]}
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>
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<footer />
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</View>
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</View>
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</RCTScrollView>
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`;
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exports[`VirtualizedList renders empty list 1`] = `
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<RCTScrollView
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data={Array []}
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disableVirtualization={false}
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getItem={[Function]}
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getItemCount={[Function]}
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horizontal={false}
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initialNumToRender={10}
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keyExtractor={[Function]}
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maxToRenderPerBatch={10}
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onContentSizeChange={[Function]}
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onEndReachedThreshold={2}
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onLayout={[Function]}
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onScroll={[Function]}
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onScrollBeginDrag={[Function]}
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renderItem={[Function]}
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renderScrollComponent={[Function]}
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scrollEventThrottle={50}
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stickyHeaderIndices={Array []}
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updateCellsBatchingPeriod={50}
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windowSize={21}
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>
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<View />
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</RCTScrollView>
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`;
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exports[`VirtualizedList renders null list 1`] = `
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<RCTScrollView
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data={undefined}
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disableVirtualization={false}
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getItem={[Function]}
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getItemCount={[Function]}
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horizontal={false}
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initialNumToRender={10}
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keyExtractor={[Function]}
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maxToRenderPerBatch={10}
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onContentSizeChange={[Function]}
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onEndReachedThreshold={2}
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onLayout={[Function]}
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onScroll={[Function]}
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onScrollBeginDrag={[Function]}
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renderItem={[Function]}
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renderScrollComponent={[Function]}
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scrollEventThrottle={50}
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stickyHeaderIndices={Array []}
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updateCellsBatchingPeriod={50}
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windowSize={21}
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>
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<View />
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</RCTScrollView>
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`;
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exports[`VirtualizedList renders simple list 1`] = `
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<RCTScrollView
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data={
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Array [
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Object {
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"key": "i1",
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},
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Object {
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"key": "i2",
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},
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Object {
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"key": "i3",
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},
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]
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}
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disableVirtualization={false}
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getItem={[Function]}
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getItemCount={[Function]}
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horizontal={false}
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initialNumToRender={10}
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keyExtractor={[Function]}
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maxToRenderPerBatch={10}
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onContentSizeChange={[Function]}
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onEndReachedThreshold={2}
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onLayout={[Function]}
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onScroll={[Function]}
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onScrollBeginDrag={[Function]}
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renderItem={[Function]}
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renderScrollComponent={[Function]}
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scrollEventThrottle={50}
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stickyHeaderIndices={Array []}
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updateCellsBatchingPeriod={50}
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windowSize={21}
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>
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<View>
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<View
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onLayout={[Function]}
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>
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<item
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value="i1"
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/>
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</View>
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<View
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onLayout={[Function]}
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>
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<item
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value="i2"
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/>
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</View>
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<View
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onLayout={[Function]}
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>
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<item
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value="i3"
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/>
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</View>
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</View>
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</RCTScrollView>
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`;
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exports[`VirtualizedList test getItem functionality where data is not an Array 1`] = `
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<RCTScrollView
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data={
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Map {
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"id_0" => Object {
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"key": "item_0",
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},
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}
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}
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disableVirtualization={false}
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getItem={[Function]}
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getItemCount={[Function]}
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horizontal={false}
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initialNumToRender={10}
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keyExtractor={[Function]}
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maxToRenderPerBatch={10}
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onContentSizeChange={[Function]}
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onEndReachedThreshold={2}
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onLayout={[Function]}
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onScroll={[Function]}
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onScrollBeginDrag={[Function]}
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renderItem={[Function]}
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renderScrollComponent={[Function]}
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scrollEventThrottle={50}
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stickyHeaderIndices={Array []}
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updateCellsBatchingPeriod={50}
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windowSize={21}
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>
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<View>
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<View
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onLayout={[Function]}
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>
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<item
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value="item_0"
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/>
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</View>
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</View>
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</RCTScrollView>
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`;
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