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Added missing tests for Standalone fusebox shell #55460

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64a5b42
chore: added missing tests for StandaloneFuseboxShell
chicio Feb 7, 2026
2cfcb68
chore: improved assertion for prepareFuseboxShell
chicio Feb 7, 2026
14e9e2a
Merge branch 'main' of https://github.com/facebook/react-native into …
chicio Feb 9, 2026
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251 changes: 166 additions & 85 deletions packages/dev-middleware/src/__tests__/StandaloneFuseboxShell-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@
*/

import type {JsonPagesListResponse} from '../inspector-proxy/types';
import type {BrowserLauncher} from '../types/BrowserLauncher';
import type {DebuggerShellPreparationResult} from '../types/BrowserLauncher';

import DefaultBrowserLauncher from '../utils/DefaultBrowserLauncher';
import {fetchJson, requestLocal} from './FetchUtils';
Expand All @@ -22,114 +22,195 @@ const PAGES_POLLING_DELAY = 2100;

jest.useFakeTimers();

describe('enableStandaloneFuseboxShell experiment', () => {
const BrowserLauncherWithFuseboxShell: BrowserLauncher = {
...DefaultBrowserLauncher,
unstable_showFuseboxShell: () => {
throw new Error('Not implemented');
},
unstable_prepareFuseboxShell: async () => {
return {code: 'not_implemented'};
},
};
const serverRef = withServerForEachTest({
logger: undefined,
unstable_browserLauncher: BrowserLauncherWithFuseboxShell,
unstable_experiments: {
enableStandaloneFuseboxShell: true,
async function setupDevice(
serverRef: {+serverBaseWsUrl: string, ...},
signal: AbortSignal,
) {
const device = await createDeviceMock(
`${serverRef.serverBaseWsUrl}/inspector/device?device=device1&name=foo&app=bar`,
signal,
);
device.getPages.mockImplementation(() => [
{
app: 'bar-app',
id: 'page1',
title: 'bar-title',
vm: 'bar-vm',
capabilities: {
nativePageReloads: true,
prefersFuseboxFrontend: true,
},
},
});
]);
jest.advanceTimersByTime(PAGES_POLLING_DELAY);

return device;
}

describe('enableStandaloneFuseboxShell experiment', () => {
const launchDebuggerAppWindow = jest.fn(async (_): Promise<void> => {});
const unstable_showFuseboxShell = jest.fn(async (_, __): Promise<void> => {});

const autoCleanup = withAbortSignalForEachTest();

afterEach(() => {
jest.clearAllMocks();
});

describe('/open-debugger endpoint', () => {
test('launches the shell with a frontend URL and stable window key', async () => {
// Connect a device to use when opening the debugger
const device = await createDeviceMock(
`${serverRef.serverBaseWsUrl}/inspector/device?device=device1&name=foo&app=bar`,
autoCleanup.signal,
describe('success', () => {
const unstable_prepareFuseboxShell = jest.fn(
async (): Promise<DebuggerShellPreparationResult> => ({
code: 'not_implemented',
}),
);
device.getPages.mockImplementation(() => [
{
app: 'bar-app',
id: 'page1',
title: 'bar-title',
vm: 'bar-vm',
capabilities: {
// Ensure the device target can be found when launching the debugger
nativePageReloads: true,
// Mark as Fusebox
prefersFuseboxFrontend: true,
},
const successfulServer = withServerForEachTest({
logger: undefined,
unstable_browserLauncher: {
...DefaultBrowserLauncher,
launchDebuggerAppWindow,
unstable_showFuseboxShell,
unstable_prepareFuseboxShell,
},
unstable_experiments: {
enableStandaloneFuseboxShell: true,
},
]);
jest.advanceTimersByTime(PAGES_POLLING_DELAY);

const launchDebuggerAppWindowSpy = jest
.spyOn(BrowserLauncherWithFuseboxShell, 'launchDebuggerAppWindow')
.mockResolvedValue();
const showFuseboxShellSpy = jest
.spyOn(BrowserLauncherWithFuseboxShell, 'unstable_showFuseboxShell')
.mockResolvedValue();

try {
// Fetch the target information for the device
const pageListResponse = await fetchJson<JsonPagesListResponse>(
`${serverRef.serverBaseUrl}/json`,
);
// Select the first target from the page list response
expect(pageListResponse.length).toBeGreaterThanOrEqual(1);
const firstPage = pageListResponse[0];

// Build the URL for the debugger
const openUrl = new URL('/open-debugger', serverRef.serverBaseUrl);
openUrl.searchParams.set('launchId', 'launch1');
openUrl.searchParams.set(
'device',
firstPage.reactNative.logicalDeviceId,
);
openUrl.searchParams.set('target', firstPage.id);
// Request to open the debugger for the first device
{
});

test('launches the shell with a frontend URL and stable window key', async () => {
// Connect a device to use when opening the debugger
const device = await setupDevice(successfulServer, autoCleanup.signal);

try {
// Fetch the target information for the device
const pageListResponse = await fetchJson<JsonPagesListResponse>(
`${successfulServer.serverBaseUrl}/json`,
);
// Select the first target from the page list response
expect(pageListResponse.length).toBeGreaterThanOrEqual(1);
const firstPage = pageListResponse[0];

// Build the URL for the debugger
const openUrl = new URL(
'/open-debugger',
successfulServer.serverBaseUrl,
);
openUrl.searchParams.set('launchId', 'launch1');
openUrl.searchParams.set(
'device',
firstPage.reactNative.logicalDeviceId,
);
openUrl.searchParams.set('target', firstPage.id);
// Request to open the debugger for the first device
const response = await requestLocal(openUrl.toString(), {
method: 'POST',
});

// Ensure the request was handled properly
expect(response.statusCode).toBe(200);

// Ensure the debugger was launched using the standalone shell API
expect(unstable_showFuseboxShell).toHaveBeenCalledWith(
expect.any(String),
expect.any(String),
);

// No call to the regular browser launcher since standalone shell should be used
expect(launchDebuggerAppWindow).not.toHaveBeenCalled();

const firstWindowKey = unstable_showFuseboxShell.mock.calls[0][1];

unstable_showFuseboxShell.mockClear();
openUrl.searchParams.set('launchId', 'launch2');

const anotherResponse = await requestLocal(openUrl.toString(), {
method: 'POST',
});

// Ensure the request was handled properly
expect(anotherResponse.statusCode).toBe(200);

// Ensure the debugger was launched using the standalone shell API and the same window key
expect(unstable_showFuseboxShell).toHaveBeenCalledWith(
expect.any(String),
firstWindowKey,
);

// Ensure the debugger preparation function was called, just one time, during middleware initialization
expect(unstable_prepareFuseboxShell).toHaveBeenCalledTimes(1);

// No fallback needed
expect(launchDebuggerAppWindow).not.toHaveBeenCalled();
} finally {
device.close();
}
openUrl.searchParams.set('launchId', 'launch1');
});
});

describe('unstable_prepareFuseboxShell failures', () => {
const unstable_prepareFuseboxShell = jest.fn(
async (): Promise<DebuggerShellPreparationResult> => ({
code: 'platform_not_supported',
}),
);
const failingServerRef = withServerForEachTest({
logger: undefined,
unstable_browserLauncher: {
...DefaultBrowserLauncher,
launchDebuggerAppWindow,
unstable_showFuseboxShell,
unstable_prepareFuseboxShell,
},
unstable_experiments: {
enableStandaloneFuseboxShell: true,
},
});

// Ensure the debugger was launched using the standalone shell API
expect(showFuseboxShellSpy).toHaveBeenCalledWith(
expect.any(String),
expect.any(String),
);
const firstWindowKey = showFuseboxShellSpy.mock.calls[0][1];
test('falls back to browser window when preparation fails', async () => {
// Connect a device to use when opening the debugger
const device = await setupDevice(failingServerRef, autoCleanup.signal);

showFuseboxShellSpy.mockClear();
openUrl.searchParams.set('launchId', 'launch2');
try {
// Fetch the target information for the device
const pageListResponse = await fetchJson<JsonPagesListResponse>(
`${failingServerRef.serverBaseUrl}/json`,
);
// Select the first target from the page list response
expect(pageListResponse.length).toBeGreaterThanOrEqual(1);
const firstPage = pageListResponse[0];

{
// Build the URL for the debugger
const openUrl = new URL(
'/open-debugger',
failingServerRef.serverBaseUrl,
);
openUrl.searchParams.set('launchId', 'launch1');
openUrl.searchParams.set(
'device',
firstPage.reactNative.logicalDeviceId,
);
openUrl.searchParams.set('target', firstPage.id);

// Request to open the debugger for the first device
const response = await requestLocal(openUrl.toString(), {
method: 'POST',
});

// Ensure the request was handled properly
expect(response.statusCode).toBe(200);

// Debugger was launched but will fail to prepare standalone shell
expect(unstable_prepareFuseboxShell).toHaveBeenCalled();

// Debugger is not launched with standalone shell since preparation failed
expect(unstable_showFuseboxShell).not.toHaveBeenCalled();

// Debugger fallback
expect(launchDebuggerAppWindow).toHaveBeenCalled();
} finally {
device.close();
}
// Ensure the debugger was launched using the standalone shell API and the same window key
expect(showFuseboxShellSpy).toHaveBeenCalledWith(
expect.any(String),
firstWindowKey,
);

expect(launchDebuggerAppWindowSpy).not.toHaveBeenCalled();
} finally {
device.close();
}
});
});

// TODO(moti): Add tests around unstable_prepareFuseboxShell
});
});
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