fix: resolve segfault issue caused by "node:events" import (#1885)

Co-authored-by: Artem Zakharchenko <kettanaito@gmail.com>

.github/workflows/ci.yml

@@ -40,6 +40,9 @@ jobs:
       - name: Browser tests
         run: pnpm test:browser
 
+      - name: Native tests
+        run: pnpm test:native
+
       - name: Upload test artifacts
         if: always()
         uses: actions/upload-artifact@v3

package.json

@@ -49,9 +49,10 @@
     "build": "pnpm clean && cross-env NODE_ENV=production tsup && pnpm patch:dts",
     "patch:dts": "node \"./config/scripts/patch-ts.js\"",
     "check:exports": "node \"./config/scripts/validate-esm.js\"",
-    "test": "pnpm test:unit && pnpm test:node && pnpm test:browser",
+    "test": "pnpm test:unit && pnpm test:node && pnpm test:browser && pnpm test:native",
     "test:unit": "vitest",
     "test:node": "vitest run --config=./test/node/vitest.config.ts",
+    "test:native": "vitest run --config=./test/native/vitest.config.ts",
     "test:browser": "playwright test -c ./test/browser/playwright.config.ts",
     "test:modules:node": "vitest run --config=./test/modules/node/vitest.config.ts",
     "test:modules:browser": "playwright test -c ./test/modules/browser/playwright.config.ts",

src/core/SetupApi.ts

@@ -47,7 +47,7 @@ export abstract class SetupApi<EventsMap extends EventMap> extends Disposable {
       invariant(
         !Array.isArray(handler),
         devUtils.formatMessage(
-          'Failed to construct "%s" given an Array of request handlers. Make sure you spread the request handlers when calling the respective setup function.',
+          'Failed to apply given request handlers: invalid input. Did you forget to spread the request handlers Array?',
         ),
         this.constructor.name,
       )

src/node/SetupServerApi.ts

@@ -1,19 +1,18 @@
-import { invariant } from 'outvariant'
 import {
   BatchInterceptor,
   HttpRequestEventMap,
   Interceptor,
   InterceptorReadyState,
 } from '@mswjs/interceptors'
+import { invariant } from 'outvariant'
 import { SetupApi } from '~/core/SetupApi'
 import { RequestHandler } from '~/core/handlers/RequestHandler'
 import { LifeCycleEventsMap, SharedOptions } from '~/core/sharedOptions'
 import { RequiredDeep } from '~/core/typeUtils'
-import { mergeRight } from '~/core/utils/internal/mergeRight'
 import { handleRequest } from '~/core/utils/handleRequest'
 import { devUtils } from '~/core/utils/internal/devUtils'
-import { SetupServer, SetupServerInternalContext } from './glossary'
-import { isNodeExceptionLike } from './utils/isNodeExceptionLike'
+import { mergeRight } from '~/core/utils/internal/mergeRight'
+import { SetupServer } from './glossary'
 
 const DEFAULT_LISTEN_OPTIONS: RequiredDeep<SharedOptions> = {
   onUnhandledRequest: 'warn',
@@ -23,7 +22,6 @@ export class SetupServerApi
   extends SetupApi<LifeCycleEventsMap>
   implements SetupServer
 {
-  private context: SetupServerInternalContext
   protected readonly interceptor: BatchInterceptor<
     Array<Interceptor<HttpRequestEventMap>>,
     HttpRequestEventMap
@@ -38,7 +36,6 @@ export class SetupServerApi
   ) {
     super(...handlers)
 
-    this.context = this.createContext()
     this.interceptor = new BatchInterceptor({
       name: 'setup-server',
       interceptors: interceptors.map((Interceptor) => new Interceptor()),
@@ -48,22 +45,12 @@ export class SetupServerApi
     this.init()
   }
 
-  private createContext(): SetupServerInternalContext {
-    return {
-      get nodeEvents() {
-        return import('node:events')
-          .then((events) => events)
-          .catch(() => undefined)
-      },
-    }
-  }
-
   /**
    * Subscribe to all requests that are using the interceptor object
    */
   private init(): void {
     this.interceptor.on('request', async ({ request, requestId }) => {
-      await this.setRequestAbortSignalMaxListeners(request)
+      this.onRequest(request)
 
       const response = await handleRequest(
         request,
@@ -126,54 +113,10 @@ export class SetupServerApi
     this.dispose()
   }
 
-  /**
-   * Bump the maximum number of event listeners on the
-   * request's "AbortSignal". This prepares the request
-   * for each request handler cloning it at least once.
-   * Note that cloning a request automatically appends a
-   * new "abort" event listener to the parent request's
-   * "AbortController" so if the parent aborts, all the
-   * clones are automatically aborted.
-   */
-  private async setRequestAbortSignalMaxListeners(
-    request: Request,
-  ): Promise<void> {
-    const events = await this.context.nodeEvents
-
-    /**
-     * @note React Native doesn't support "node:events".
-     */
-    if (typeof events === 'undefined') {
-      return
-    }
-
-    const { setMaxListeners, defaultMaxListeners } = events
-
-    if (typeof setMaxListeners !== 'function') {
-      return
-    }
-
-    try {
-      setMaxListeners(
-        Math.max(defaultMaxListeners, this.currentHandlers.length),
-        request.signal,
-      )
-    } catch (error: unknown) {
-      /**
-       * @note Mock environments (JSDOM, ...) are not able to implement an internal
-       * "kIsNodeEventTarget" Symbol that Node.js uses to identify Node.js `EventTarget`s.
-       * `setMaxListeners` throws an error for non-Node.js `EventTarget`s.
-       * At the same time, mock environments are also not able to implement the
-       * internal "events.maxEventTargetListenersWarned" Symbol, which results in
-       * "MaxListenersExceededWarning" not being printed by Node.js for those anyway.
-       * The main reason for using `setMaxListeners` is to suppress these warnings in Node.js,
-       * which won't be printed anyway if `setMaxListeners` fails.
-       */
-      if (
-        !(isNodeExceptionLike(error) && error.code === 'ERR_INVALID_ARG_TYPE')
-      ) {
-        throw error
-      }
-    }
+  protected onRequest(request: Request): void {
+    // Do nothing here.
+    // Subclasses may hook into the request being intercepted
+    // to provide additional functionality (e.g. setting the max
+    // event listener count on request's "AbortController" in Node.js).
   }
 }

src/node/glossary.ts

@@ -60,7 +60,3 @@ export interface SetupServer {
    */
   events: LifeCycleEventEmitter<LifeCycleEventsMap>
 }
-
-export type SetupServerInternalContext = {
-  get nodeEvents(): Promise<typeof import('node:events') | undefined>
-}

src/node/setupServer.ts

@@ -1,9 +1,47 @@
 import { ClientRequestInterceptor } from '@mswjs/interceptors/ClientRequest'
 import { XMLHttpRequestInterceptor } from '@mswjs/interceptors/XMLHttpRequest'
 import { FetchInterceptor } from '@mswjs/interceptors/fetch'
+import { defaultMaxListeners, setMaxListeners } from 'node:events'
 import { RequestHandler } from '~/core/handlers/RequestHandler'
+import { SetupServerApi as BaseSetupServerApi } from './SetupServerApi'
 import { SetupServer } from './glossary'
-import { SetupServerApi } from './SetupServerApi'
+import { isNodeExceptionLike } from './utils/isNodeExceptionLike'
+
+class SetupServerApi extends BaseSetupServerApi implements SetupServer {
+  /**
+   * Bump the maximum number of event listeners on the
+   * request's "AbortSignal". This prepares the request
+   * for each request handler cloning it at least once.
+   * Note that cloning a request automatically appends a
+   * new "abort" event listener to the parent request's
+   * "AbortController" so if the parent aborts, all the
+   * clones are automatically aborted.
+   */
+  protected override onRequest(request: Request): void {
+    try {
+      setMaxListeners(
+        Math.max(defaultMaxListeners, this.currentHandlers.length),
+        request.signal,
+      )
+    } catch (error: unknown) {
+      /**
+       * @note Mock environments (JSDOM, ...) are not able to implement an internal
+       * "kIsNodeEventTarget" Symbol that Node.js uses to identify Node.js `EventTarget`s.
+       * `setMaxListeners` throws an error for non-Node.js `EventTarget`s.
+       * At the same time, mock environments are also not able to implement the
+       * internal "events.maxEventTargetListenersWarned" Symbol, which results in
+       * "MaxListenersExceededWarning" not being printed by Node.js for those anyway.
+       * The main reason for using `setMaxListeners` is to suppress these warnings in Node.js,
+       * which won't be printed anyway if `setMaxListeners` fails.
+       */
+      if (
+        !(isNodeExceptionLike(error) && error.code === 'ERR_INVALID_ARG_TYPE')
+      ) {
+        throw error
+      }
+    }
+  }
+}
 
 /**
  * Sets up a requests interception in Node.js with the given request handlers.

test/browser/msw-api/setup-worker/input-validation.test.ts

@@ -20,7 +20,7 @@ test('throws an error given an Array of request handlers to "setupWorker"', asyn
     expect(exceptions).toEqual(
       expect.arrayContaining([
         expect.stringContaining(
-          '[MSW] Failed to construct "SetupWorkerApi" given an Array of request handlers. Make sure you spread the request handlers when calling the respective setup function.',
+          '[MSW] Failed to apply given request handlers: invalid input. Did you forget to spread the request handlers Array?',
         ),
       ]),
     )

test/native/node-events.native.test.ts

@@ -0,0 +1,22 @@
+/**
+ * @see https://github.com/mswjs/msw/pull/1858
+ * @see https://github.com/mswjs/msw/issues/1868
+ */
+import { setupServer } from 'msw/native'
+
+test('calls "setupServer" without errors in React Native', async () => {
+  /**
+   * @note Asserting that mocking works is not possible with
+   * the current testing setup. We force Vitest to alias "msw"
+   * imports to their ESM build, which is a hack.
+   *
+   * We need Vitest to load the ESM build here in order to
+   * use "vi.mock()" to mock the "node:events" imports to throw.
+   * Vitest doesn't support module mocking in CommonJS.
+   *
+   * But aliasing the build isn't enough for it to function.
+   * The root-level package.json is still CJS, which, I suspects,
+   * resolves any subsequent in-build imports to their CJS counterparts.
+   */
+  expect(() => setupServer()).not.toThrow()
+})

test/native/tsconfig.json

@@ -0,0 +1,22 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "esnext",
+    "baseUrl": ".",
+    "paths": {
+      "msw": ["../.."],
+      "msw/*": ["../../*"]
+    },
+    "noEmit": true,
+    "declaration": false,
+    "resolveJsonModule": true,
+    // Support default imports for modules that have no default exports.
+    // This way "http" imports stay "import http from 'http'".
+    // Using wildcard there breaks request interception since it
+    // encapsulates the values under the ".default" key.
+    "allowSyntheticDefaultImports": true,
+    "types": ["node", "vitest/globals"]
+  },
+  "include": ["../../global.d.ts", "./**/*.test.ts"]
+}

test/native/vitest.config.ts

@@ -0,0 +1,28 @@
+import * as path from 'node:path'
+import { defineConfig } from 'vitest/config'
+
+const LIB_DIR = path.resolve(__dirname, '../../lib')
+
+export default defineConfig({
+  test: {
+    root: './test/native',
+    include: ['**/*.native.test.ts'],
+    globals: true,
+    setupFiles: ['./vitest.setup.ts'],
+    alias: {
+      /**
+       * @note Force Vitest load ESM targets of MSW.
+       * If we run ESM in tests, we can use "vi.mock()" to
+       * emulate certain standard Node.js modules missing
+       * (like "node:events") in React Native.
+       *
+       * Vitest won't pick up the ESM targets because
+       * the root-level "package.json" is not "module".
+       */
+      'msw/node': path.resolve(LIB_DIR, 'node/index.mjs'),
+      'msw/native': path.resolve(LIB_DIR, 'native/index.mjs'),
+      'msw/browser': path.resolve(LIB_DIR, 'browser/index.mjs'),
+      msw: path.resolve(LIB_DIR, 'core/index.mjs'),
+    },
+  },
+})

test/native/vitest.setup.ts

@@ -0,0 +1,15 @@
+import { vi } from 'vitest'
+
+/**
+ * @note The list of standard Node.js modules missing
+ * in the React Native runtime.
+ */
+const reactNativeMissingModules = ['events', 'node:events']
+
+reactNativeMissingModules.forEach((moduleName) => {
+  vi.doMock(moduleName, () => {
+    throw new Error(
+      `Failed to import module "${moduleName}": it does not exist in React Native. This likely means MSW tries to import something too optimistically in that environment.`,
+    )
+  })
+})

test/node/msw-api/setup-server/input-validation.node.test.ts

@@ -1,7 +1,7 @@
 import { HttpResponse, http } from 'msw'
 import { setupServer } from 'msw/node'
 
-test('throws an error given an Array of request handlers to setupServer', () => {
+test('throws an error given an Array of request handlers to "setupServer"', () => {
   const createServer = () => {
     // @ts-expect-error intentionally invalid parameters for setupServer to force it to throw
     return setupServer([
@@ -12,6 +12,6 @@ test('throws an error given an Array of request handlers to setupServer', () =>
   }
 
   expect(createServer).toThrow(
-    `[MSW] Failed to construct "SetupServerApi" given an Array of request handlers. Make sure you spread the request handlers when calling the respective setup function.`,
+    `[MSW] Failed to apply given request handlers: invalid input. Did you forget to spread the request handlers Array?`,
   )
 })