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Add option to pass contentSize and layoutMeasurement when calling scrollTo #1543

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merged 7 commits into from
Dec 15, 2023
Merged

Add option to pass contentSize and layoutMeasurement when calling scrollTo #1543

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12a5335
Add option to pass `contentSize` and `layoutMeasurement` when calling…
j-piasecki Dec 13, 2023
3f10d73
Update docs
j-piasecki Dec 13, 2023
6e2e6c2
Add tests
j-piasecki Dec 15, 2023
a021500
refactor: code review changes
mdjastrzebski Dec 15, 2023
711722e
refactor: code review changes
mdjastrzebski Dec 15, 2023
c1f58dd
refactor: code review changes
mdjastrzebski Dec 15, 2023
1b16e92
docs: fix typo
mdjastrzebski Dec 15, 2023
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16 changes: 12 additions & 4 deletions src/user-event/event-builder/scroll-view.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
import type { ScrollToOptions } from '../scroll';

/**
* Experimental values:
* - iOS: `{"contentInset": {"bottom": 0, "left": 0, "right": 0, "top": 0}, "contentOffset": {"x": 0, "y": 5.333333333333333}, "contentSize": {"height": 1676.6666259765625, "width": 390}, "layoutMeasurement": {"height": 753, "width": 390}, "zoomScale": 1}`
Expand All @@ -13,15 +15,21 @@ export interface ContentOffset {
}

export const ScrollViewEventBuilder = {
scroll: (offset: ContentOffset = { y: 0, x: 0 }) => {
scroll: (
offset: ContentOffset = { y: 0, x: 0 },
options?: ScrollToOptions
) => {
return {
nativeEvent: {
contentInset: { bottom: 0, left: 0, right: 0, top: 0 },
contentOffset: { y: offset.y, x: offset.x },
contentSize: { height: 0, width: 0 },
contentSize: {
height: options?.contentSize?.height ?? 0,
width: options?.contentSize?.width ?? 0,
},
layoutMeasurement: {
height: 0,
width: 0,
height: options?.layoutMeasurement?.height ?? 0,
width: options?.layoutMeasurement?.width ?? 0,
},
responderIgnoreScroll: true,
target: 0,
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53 changes: 41 additions & 12 deletions src/user-event/scroll/scroll-to.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -7,14 +7,27 @@ import { isHostScrollView } from '../../helpers/host-component-names';
import { pick } from '../../helpers/object';
import { dispatchEvent, wait } from '../utils';
import { ContentOffset } from '../event-builder/scroll-view';
import fireEvent from '../../fire-event';
import {
createScrollSteps,
inertialInterpolator,
linearInterpolator,
} from './utils';
import { getElementScrollOffset, setElementScrollOffset } from './state';

export interface VerticalScrollToOptions {
interface CommonScrollToOptions {
contentSize?: {
height: number;
width: number;
};

layoutMeasurement?: {
height: number;
width: number;
};
}

export interface VerticalScrollToOptions extends CommonScrollToOptions {
y: number;
momentumY?: number;

Expand All @@ -23,7 +36,7 @@ export interface VerticalScrollToOptions {
momentumX?: never;
}

export interface HorizontalScrollToOptions {
export interface HorizontalScrollToOptions extends CommonScrollToOptions {
x: number;
momentumX?: number;

Expand All @@ -50,31 +63,46 @@ export async function scrollTo(

ensureScrollViewDirection(element, options);

emitContentSizeChangeEvent(element, options);
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✅ The sequencing of this event matches our experiments with RN runtime:
https://github.com/callstack/react-native-testing-library/wiki/ScrollView-Events


const initialPosition = getElementScrollOffset(element);
const dragSteps = createScrollSteps(
{ y: options.y, x: options.x },
initialPosition,
linearInterpolator
);
await emitDragScrollEvents(this.config, element, dragSteps);
await emitDragScrollEvents(this.config, element, dragSteps, options);

const momentumStart = dragSteps.at(-1) ?? initialPosition;
const momentumSteps = createScrollSteps(
{ y: options.momentumY, x: options.momentumX },
momentumStart,
inertialInterpolator
);
await emitMomentumScrollEvents(this.config, element, momentumSteps);
await emitMomentumScrollEvents(this.config, element, momentumSteps, options);

const finalPosition =
momentumSteps.at(-1) ?? dragSteps.at(-1) ?? initialPosition;
setElementScrollOffset(element, finalPosition);
}

function emitContentSizeChangeEvent(
element: ReactTestInstance,
options: ScrollToOptions
) {
fireEvent(
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replace with dispatchEvent

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dispatchEvent has a different signature than fireEvent. It expects event to be its last argument and passes that directly to the handler, while fireEvent accepts variadic arguments and spreads them when passing to the handler.

contentSizeChange handler expects width and height as separate arguments: https://github.com/facebook/react-native/blob/d45a01d6d15530e356065704adb869b1cbbb2576/packages/virtualized-lists/Lists/VirtualizedList.js#L1574

Should I also change the signature of dispatchEvent to accept variadic arguments, or is fireEvent fine in that case?

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Fair point, I'll add some dispatch function for such cases.

element,
'contentSizeChange',
options.contentSize?.width ?? 0,
options.contentSize?.height ?? 0
);
}

async function emitDragScrollEvents(
config: UserEventConfig,
element: ReactTestInstance,
scrollSteps: ContentOffset[]
scrollSteps: ContentOffset[],
scrollOptions: ScrollToOptions
) {
if (scrollSteps.length === 0) {
return;
Expand All @@ -84,7 +112,7 @@ async function emitDragScrollEvents(
dispatchEvent(
element,
'scrollBeginDrag',
EventBuilder.ScrollView.scroll(scrollSteps[0])
EventBuilder.ScrollView.scroll(scrollSteps[0], scrollOptions)
);

// Note: experimentally, in case of drag scroll the last scroll step
Expand All @@ -95,7 +123,7 @@ async function emitDragScrollEvents(
dispatchEvent(
element,
'scroll',
EventBuilder.ScrollView.scroll(scrollSteps[i])
EventBuilder.ScrollView.scroll(scrollSteps[i], scrollOptions)
);
}

Expand All @@ -104,14 +132,15 @@ async function emitDragScrollEvents(
dispatchEvent(
element,
'scrollEndDrag',
EventBuilder.ScrollView.scroll(lastStep)
EventBuilder.ScrollView.scroll(lastStep, scrollOptions)
);
}

async function emitMomentumScrollEvents(
config: UserEventConfig,
element: ReactTestInstance,
scrollSteps: ContentOffset[]
scrollSteps: ContentOffset[],
scrollOptions: ScrollToOptions
) {
if (scrollSteps.length === 0) {
return;
Expand All @@ -121,7 +150,7 @@ async function emitMomentumScrollEvents(
dispatchEvent(
element,
'momentumScrollBegin',
EventBuilder.ScrollView.scroll(scrollSteps[0])
EventBuilder.ScrollView.scroll(scrollSteps[0], scrollOptions)
);

// Note: experimentally, in case of momentum scroll the last scroll step
Expand All @@ -132,7 +161,7 @@ async function emitMomentumScrollEvents(
dispatchEvent(
element,
'scroll',
EventBuilder.ScrollView.scroll(scrollSteps[i])
EventBuilder.ScrollView.scroll(scrollSteps[i], scrollOptions)
);
}

Expand All @@ -141,7 +170,7 @@ async function emitMomentumScrollEvents(
dispatchEvent(
element,
'momentumScrollEnd',
EventBuilder.ScrollView.scroll(lastStep)
EventBuilder.ScrollView.scroll(lastStep, scrollOptions)
);
}

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6 changes: 6 additions & 0 deletions website/docs/UserEvent.md
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Original file line number Diff line number Diff line change
Expand Up @@ -204,9 +204,13 @@ scrollTo(
options: {
y: number,
momentumY?: number,
contentSize?: { width: number, height: number },
layoutMeasurement?: { width: number, height: number },
} | {
x: number,
momentumX?: number,
contentSize?: { width: number, height: number },
layoutMeasurement?: { width: number, height: number },
}
```

Expand All @@ -221,6 +225,8 @@ This helper simulates user scrolling a host `ScrollView` element.

This function supports only host `ScrollView` elements, passing other element types will result in error. Note that `FlatList` is accepted as it renders to a host `ScrolLView` element, however in the current iteration we focus only on base `ScrollView` only features.

If you want to simulate scrolling a `FlatList` or any other `VirtualizedList`, you should also pass `contentSize` and `layoutMeasurement` options, to run underlying logic that updates the currently visible window.

Scroll interaction should match `ScrollView` element direction. For vertical scroll view (default or explicit `horizontal={false}`) you should pass only `y` (and optionally also `momentumY`) option, for horizontal scroll view (`horizontal={true}`) you should pass only `x` (and optionally `momentumX`) option.

Each scroll interaction consists of a mandatory drag scroll part which simulates user dragging the scroll view with his finger (`y` or `x` option). This may optionally be followed by a momentum scroll movement which simulates the inertial movement of scroll view content after the user lifts his finger up (`momentumY` or `momentumX` options).
Expand Down