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add preload test
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‎versioned_docs/version-7.x/testing.md‎

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@@ -79,7 +79,9 @@ If you're not using Jest, then you'll need to mock these modules according to th
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We recommend using [React Native Testing Library](https://callstack.github.io/react-native-testing-library/) along with [`jest-native`](https://github.com/testing-library/jest-native) to write your tests.
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We are going to write example tests illustrating the difference between `navigate` and `push` functions using `RootNavigator` defined below:
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We are going to write example tests illustrating the difference between `navigate` and `push` functions, drawer's screens `preload` and times functions in tests.
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To show the difference between `navigate` and `push` functions, we will use `RootNavigator` defined below:
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<Tabs groupId="example" queryString="example">
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<TabItem value="static" label="Static" default>
@@ -299,6 +301,285 @@ test('pushes settings screen twice', () => {
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</TabItem>
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</Tabs>
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To show how drawer's screens `preload` works, we will compare two tests - with and without preloading.
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Without preloading test example:
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<Tabs groupId="example" queryString="example">
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<TabItem value="static" label="Static" default>
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```js
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import { expect, test } from '@jest/globals';
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import { createDrawerNavigator } from '@react-navigation/drawer';
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import {
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createNavigationContainerRef,
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createStaticNavigation,
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useNavigation,
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} from '@react-navigation/native';
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import { fireEvent, render, screen } from '@testing-library/react-native';
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import { Button, Text, View } from 'react-native';
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const Profile = () => {
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const navigation = useNavigation();
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return (
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<View>
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<Text>Profile Screen</Text>
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<Button
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onPress={() => navigation.navigate('Settings')}
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title="Navigate to Settings"
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/>
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</View>
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);
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};
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let renderCounter = 0;
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const Settings = () => {
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renderCounter++;
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return (
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<View>
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<Text>Settings Screen</Text>
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</View>
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);
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};
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const Drawer = createDrawerNavigator({
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screens: {
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Profile,
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Settings,
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},
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});
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const DrawerNavigation = createStaticNavigation(Drawer);
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test('navigates to settings without previous preload', () => {
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const navigation = createNavigationContainerRef();
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render(<DrawerNavigation ref={navigation} />);
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expect(screen.queryByText('Profile Screen')).toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).not.toBeOnTheScreen();
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expect(renderCounter).toBe(0);
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fireEvent.press(screen.queryByText('Navigate to Settings'));
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expect(screen.queryByText('Profile Screen')).not.toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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});
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```
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</TabItem>
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<TabItem value="dynamic" label="Dynamic">
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```js
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import { expect, test } from '@jest/globals';
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import { createDrawerNavigator } from '@react-navigation/drawer';
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import {
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createNavigationContainerRef,
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NavigationContainer,
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} from '@react-navigation/native';
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import { fireEvent, render, screen } from '@testing-library/react-native';
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import { Button, Text, View } from 'react-native';
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const Profile = ({ navigation }) => {
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return (
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<View>
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<Text>Profile Screen</Text>
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<Button
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onPress={() => navigation.navigate('Settings')}
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title="Navigate to Settings"
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/>
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</View>
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);
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};
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let renderCounter = 0;
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const Settings = () => {
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renderCounter++;
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return (
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<View>
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<Text>Settings Screen</Text>
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</View>
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);
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};
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const Drawer = createDrawerNavigator();
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const DrawerNavigation = () => {
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return (
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<Drawer.Navigator>
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<Drawer.Screen name="Profile" component={Profile} />
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<Drawer.Screen name="Settings" component={Settings} />
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</Drawer.Navigator>
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);
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};
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test('navigates to settings without previous preload', () => {
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const navigation = createNavigationContainerRef();
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render(
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<NavigationContainer ref={navigation}>
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<DrawerNavigation />
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</NavigationContainer>
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);
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expect(screen.queryByText('Profile Screen')).toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).not.toBeOnTheScreen();
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expect(renderCounter).toBe(0);
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fireEvent.press(screen.queryByText('Navigate to Settings'));
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expect(screen.queryByText('Profile Screen')).not.toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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});
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```
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</TabItem>
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</Tabs>
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With preloading test example:
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<Tabs groupId="example" queryString="example">
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<TabItem value="static" label="Static" default>
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```js
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import { expect, test } from '@jest/globals';
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import { createDrawerNavigator } from '@react-navigation/drawer';
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import {
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createNavigationContainerRef,
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createStaticNavigation,
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useNavigation,
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} from '@react-navigation/native';
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import { act, fireEvent, render, screen } from '@testing-library/react-native';
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import { Button, Text, View } from 'react-native';
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const Profile = () => {
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const navigation = useNavigation();
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return (
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<View>
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<Text>Profile Screen</Text>
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<Button
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onPress={() => navigation.navigate('Settings')}
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title="Navigate to Settings"
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/>
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</View>
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);
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};
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let renderCounter = 0;
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const Settings = () => {
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renderCounter++;
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return (
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<View>
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<Text>Settings Screen</Text>
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</View>
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);
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};
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const Drawer = createDrawerNavigator({
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screens: {
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Profile,
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Settings,
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},
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});
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const DrawerNavigation = createStaticNavigation(Drawer);
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test('navigates to settings with previous preload', () => {
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const navigation = createNavigationContainerRef();
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render(<DrawerNavigation ref={navigation} />);
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expect(renderCounter).toBe(0);
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act(() => navigation.preload('Settings'));
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expect(screen.queryByText('Profile Screen')).toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).not.toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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fireEvent.press(screen.queryByText('Navigate to Settings'));
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expect(screen.queryByText('Profile Screen')).not.toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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});
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```
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</TabItem>
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<TabItem value="dynamic" label="Dynamic">
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```js
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import { expect, test } from '@jest/globals';
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import { createDrawerNavigator } from '@react-navigation/drawer';
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import {
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createNavigationContainerRef,
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NavigationContainer,
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} from '@react-navigation/native';
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import { act, fireEvent, render, screen } from '@testing-library/react-native';
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import { Button, Text, View } from 'react-native';
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const Profile = ({ navigation }) => {
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return (
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<View>
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<Text>Profile Screen</Text>
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<Button
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onPress={() => navigation.navigate('Settings')}
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title="Navigate to Settings"
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/>
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</View>
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);
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};
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let renderCounter = 0;
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const Settings = () => {
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renderCounter++;
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return (
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<View>
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<Text>Settings Screen</Text>
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</View>
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);
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};
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const Drawer = createDrawerNavigator();
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const DrawerNavigation = () => {
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return (
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<Drawer.Navigator>
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<Drawer.Screen name="Profile" component={Profile} />
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<Drawer.Screen name="Settings" component={Settings} />
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</Drawer.Navigator>
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);
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};
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test('navigates to settings with previous preload', () => {
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const navigation = createNavigationContainerRef();
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render(
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<NavigationContainer ref={navigation}>
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<DrawerNavigation />
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</NavigationContainer>
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);
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expect(renderCounter).toBe(0);
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act(() => navigation.preload('Settings'));
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expect(screen.queryByText('Profile Screen')).toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).not.toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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fireEvent.press(screen.queryByText('Navigate to Settings'));
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expect(screen.queryByText('Profile Screen')).not.toBeOnTheScreen();
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expect(screen.queryByText('Settings Screen')).toBeOnTheScreen();
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expect(renderCounter).toBe(1);
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});
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```
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</TabItem>
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</Tabs>
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For writing tests that include times functions you will need to use [Fake Timers](https://jestjs.io/docs/timer-mocks). They will replace times function implementation to use time from the fake clock.
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Let's add another button to the Profile screen, which uses `setTimeout`:

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