Only enable Node lint rules for Node files (#3672)

In a previous commit, we mistakenly introduced a Node-specific function
for testing deep equality, and this ended up crashing the extension.
This would usually have been caught by our ESLint rules, as they
prohibit use of Node libraries by default. However, the ESLint
configuration for this repo imports rules from our
`@metamask/eslint-config-nodejs` package and applies them to all files,
marking everything as Node-compatible, thereby allowing such usage. This
is incorrect: these rules should only apply to test files and scripts.

This commit fix the ESLint configuration to match. Doing so revealed a
couple of categories of violations, which this commit also fixes:

- Some packages import and make use of EventEmitter from Node's `events`
module. We add a notice to the README for these packages which advises
consumers that these packages are designed to be used in a
Node-compatible environment.
- Some packages import and make use of Node's `assert` module to check
values at runtime. It isn't strictly necessary to use this module, and
so we replace its usage with simpler code.
- Some packages import and make use of Node's `inspect` utility
function. We don't strictly need this either, and we replace its usage
with simpler code as well.

.eslintrc.js

@@ -1,9 +1,9 @@
 module.exports = {
   root: true,
-  extends: ['@metamask/eslint-config', '@metamask/eslint-config-nodejs'],
+  extends: ['@metamask/eslint-config'],
   ignorePatterns: [
     '!.eslintrc.js',
-    '!jest.config.js',
+    '!.prettierrc.js',
     'node_modules',
     '**/dist',
     '**/docs',
@@ -12,6 +12,19 @@ module.exports = {
     'scripts/create-package/package-template',
   ],
   overrides: [
+    {
+      files: [
+        '**/jest.config.js',
+        '**/jest.environment.js',
+        '**/tests/**/*.{ts,js}',
+        '*.js',
+        '*.test.{ts,js}',
+        'scripts/*.ts',
+        'scripts/create-package/*.ts',
+        'yarn.config.cjs',
+      ],
+      extends: ['@metamask/eslint-config-nodejs'],
+    },
     {
       files: ['*.test.{ts,js}', '**/tests/**/*.{ts,js}'],
       extends: ['@metamask/eslint-config-jest'],

packages/message-manager/README.md

@@ -10,6 +10,10 @@ or
 
 `npm install @metamask/message-manager`
 
+## Compatibility
+
+This package relies implicitly upon the `EventEmitter` module. This module is available natively in Node.js, but when using this package for the browser, make sure to use a polyfill such as `events`.
+
 ## Contributing
 
 This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).

packages/message-manager/src/AbstractMessageManager.ts

@@ -2,6 +2,8 @@ import type { BaseConfig, BaseState } from '@metamask/base-controller';
 import { BaseControllerV1 } from '@metamask/base-controller';
 import type { ApprovalType } from '@metamask/controller-utils';
 import type { Hex, Json } from '@metamask/utils';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import { EventEmitter } from 'events';
 import { v1 as random } from 'uuid';
 

packages/network-controller/src/NetworkController.ts

@@ -19,13 +19,11 @@ import { errorCodes } from '@metamask/rpc-errors';
 import { createEventEmitterProxy } from '@metamask/swappable-obj-proxy';
 import type { SwappableProxy } from '@metamask/swappable-obj-proxy';
 import type { Hex } from '@metamask/utils';
-import { isStrictHexString, hasProperty, isPlainObject } from '@metamask/utils';
-import { strict as assert } from 'assert';
+import { hasProperty, isPlainObject, isStrictHexString } from '@metamask/utils';
 import type { Draft } from 'immer';
 import type { Logger } from 'loglevel';
 import { createSelector } from 'reselect';
 import * as URI from 'uri-js';
-import { inspect } from 'util';
 import { v4 as uuidV4 } from 'uuid';
 
 import { INFURA_BLOCKED_KEY, NetworkStatus } from './constants';
@@ -515,7 +513,7 @@ function getDefaultNetworkConfigurationsByChainId(): Record<
   >((obj, infuraNetworkType) => {
     const chainId = ChainId[infuraNetworkType];
     const rpcEndpointUrl =
-      // False negative - this is a string.
+      // This ESLint rule mistakenly produces an error.
       // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
       `https://${infuraNetworkType}.infura.io/v3/{infuraProjectId}` as const;
 
@@ -788,9 +786,9 @@ function validateNetworkControllerState(state: NetworkState) {
 
   if (!networkClientIds.includes(state.selectedNetworkClientId)) {
     throw new Error(
-      `NetworkController state is invalid: \`selectedNetworkClientId\` ${inspect(
-        state.selectedNetworkClientId,
-      )} does not refer to an RPC endpoint within a network configuration`,
+      // This ESLint rule mistakenly produces an error.
+      // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+      `NetworkController state is invalid: \`selectedNetworkClientId\` '${state.selectedNetworkClientId}' does not refer to an RPC endpoint within a network configuration`,
     );
   }
 }
@@ -1354,19 +1352,16 @@ export class NetworkController extends BaseController<
    * removed in a future release
    */
   async setProviderType(type: InfuraNetworkType) {
-    assert.notStrictEqual(
-      type,
-      NetworkType.rpc,
-      // TODO: Either fix this lint violation or explain why it's necessary to ignore.
-      // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
-      `NetworkController - cannot call "setProviderType" with type "${NetworkType.rpc}". Use "setActiveNetwork"`,
-    );
-    assert.ok(
-      isInfuraNetworkType(type),
-      // TODO: Either fix this lint violation or explain why it's necessary to ignore.
-      // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
-      `Unknown Infura provider type "${type}".`,
-    );
+    if ((type as unknown) === NetworkType.rpc) {
+      throw new Error(
+        // This ESLint rule mistakenly produces an error.
+        // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+        `NetworkController - cannot call "setProviderType" with type "${NetworkType.rpc}". Use "setActiveNetwork"`,
+      );
+    }
+    if (!isInfuraNetworkType(type)) {
+      throw new Error(`Unknown Infura provider type "${String(type)}".`);
+    }
 
     await this.setActiveNetwork(type);
   }
@@ -1635,9 +1630,7 @@ export class NetworkController extends BaseController<
 
     if (existingNetworkConfiguration === undefined) {
       throw new Error(
-        `Could not update network: Cannot find network configuration for chain ${inspect(
-          chainId,
-        )}`,
+        `Could not update network: Cannot find network configuration for chain '${chainId}'`,
       );
     }
 
@@ -1802,7 +1795,7 @@ export class NetworkController extends BaseController<
       })
     ) {
       throw new Error(
-        // False negative - this is a string.
+        // This ESLint rule mistakenly produces an error.
         // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
         `Could not update network: Cannot update RPC endpoints in such a way that the selected network '${this.state.selectedNetworkClientId}' would be removed without a replacement. Choose a different RPC endpoint as the selected network via the \`replacementSelectedRpcEndpointIndex\` option.`,
       );
@@ -1899,7 +1892,7 @@ export class NetworkController extends BaseController<
 
     if (existingNetworkConfiguration === undefined) {
       throw new Error(
-        `Cannot find network configuration for chain ${inspect(chainId)}`,
+        `Cannot find network configuration for chain '${chainId}'`,
       );
     }
 
@@ -2031,9 +2024,7 @@ export class NetworkController extends BaseController<
       !isSafeChainId(networkFields.chainId)
     ) {
       throw new Error(
-        `${errorMessagePrefix}: Invalid \`chainId\` ${inspect(
-          networkFields.chainId,
-        )} (must start with "0x" and not exceed the maximum)`,
+        `${errorMessagePrefix}: Invalid \`chainId\` '${networkFields.chainId}' (must start with "0x" and not exceed the maximum)`,
       );
     }
 
@@ -2046,13 +2037,13 @@ export class NetworkController extends BaseController<
       if (existingNetworkConfigurationViaChainId !== undefined) {
         if (existingNetworkConfiguration === null) {
           throw new Error(
-            // False negative - these are strings.
+            // This ESLint rule mistakenly produces an error.
             // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
             `Could not add network for chain ${args.networkFields.chainId} as another network for that chain already exists ('${existingNetworkConfigurationViaChainId.name}')`,
           );
         } else {
           throw new Error(
-            // False negative - these are strings.
+            // This ESLint rule mistakenly produces an error.
             // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
             `Cannot move network from chain ${existingNetworkConfiguration.chainId} to ${networkFields.chainId} as another network for that chain already exists ('${existingNetworkConfigurationViaChainId.name}')`,
           );
@@ -2082,9 +2073,9 @@ export class NetworkController extends BaseController<
     for (const rpcEndpointFields of networkFields.rpcEndpoints) {
       if (!isValidUrl(rpcEndpointFields.url)) {
         throw new Error(
-          `${errorMessagePrefix}: An entry in \`rpcEndpoints\` has invalid URL ${inspect(
-            rpcEndpointFields.url,
-          )}`,
+          // This ESLint rule mistakenly produces an error.
+          // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+          `${errorMessagePrefix}: An entry in \`rpcEndpoints\` has invalid URL '${rpcEndpointFields.url}'`,
         );
       }
       const networkClientId =
@@ -2113,13 +2104,9 @@ export class NetworkController extends BaseController<
         )
       ) {
         throw new Error(
-          `${errorMessagePrefix}: RPC endpoint '${
-            // This is a string.
-            // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
-            rpcEndpointFields.url
-          }' refers to network client ${inspect(
-            networkClientId,
-          )} that does not exist`,
+          // This is a string.
+          // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+          `${errorMessagePrefix}: RPC endpoint '${rpcEndpointFields.url}' refers to network client '${networkClientId}' that does not exist`,
         );
       }
 
@@ -2149,15 +2136,19 @@ export class NetworkController extends BaseController<
             URI.equal(rpcEndpointFields.url, existingRpcEndpoint.url),
         );
         if (rpcEndpoint) {
-          throw new Error(
-            mode === 'update'
-              ? // False negative - these are strings.
-                // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
-                `Could not update network to point to same RPC endpoint as existing network for chain ${networkConfiguration.chainId} ('${networkConfiguration.name}')`
-              : // False negative - these are strings.
-                // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
-                `Could not add network that points to same RPC endpoint as existing network for chain ${networkConfiguration.chainId} ('${networkConfiguration.name}')`,
-          );
+          if (mode === 'update') {
+            throw new Error(
+              // This ESLint rule mistakenly produces an error.
+              // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+              `Could not update network to point to same RPC endpoint as existing network for chain ${networkConfiguration.chainId} ('${networkConfiguration.name}')`,
+            );
+          } else {
+            throw new Error(
+              // This ESLint rule mistakenly produces an error.
+              // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
+              `Could not add network that points to same RPC endpoint as existing network for chain ${networkConfiguration.chainId} ('${networkConfiguration.name}')`,
+            );
+          }
         }
       }
     }
@@ -2561,7 +2552,7 @@ export class NetworkController extends BaseController<
       /* istanbul ignore if */
       if (!possibleAutoManagedNetworkClient) {
         throw new Error(
-          `No Infura network client found with ID ${inspect(networkClientId)}`,
+          `No Infura network client found with ID '${networkClientId}'`,
         );
       }
 
@@ -2573,9 +2564,7 @@ export class NetworkController extends BaseController<
         ];
 
       if (!possibleAutoManagedNetworkClient) {
-        throw new Error(
-          `No network client found with ID ${inspect(networkClientId)}`,
-        );
+        throw new Error(`No network client found with ID '${networkClientId}'`);
       }
 
       autoManagedNetworkClient = possibleAutoManagedNetworkClient;

packages/signature-controller/README.md

@@ -10,6 +10,10 @@ or
 
 `npm install @metamask/signature-controller`
 
+## Compatibility
+
+This package relies implicitly upon the `EventEmitter` module. This module is available natively in Node.js, but when using this package for the browser, make sure to use a polyfill such as `events`.
+
 ## Contributing
 
 This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).

packages/signature-controller/src/SignatureController.ts

@@ -29,6 +29,8 @@ import {
 } from '@metamask/logging-controller';
 import type { NetworkControllerGetNetworkClientByIdAction } from '@metamask/network-controller';
 import type { Hex, Json } from '@metamask/utils';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 import { v1 as random } from 'uuid';
 

packages/transaction-controller/README.md

@@ -10,6 +10,10 @@ or
 
 `npm install @metamask/transaction-controller`
 
+## Compatibility
+
+This package relies implicitly upon the `EventEmitter` module. This module is available natively in Node.js, but when using this package for the browser, make sure to use a polyfill such as `events`.
+
 ## Contributing
 
 This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).

packages/transaction-controller/src/TransactionController.ts

@@ -46,6 +46,8 @@ import { errorCodes, rpcErrors, providerErrors } from '@metamask/rpc-errors';
 import type { Hex } from '@metamask/utils';
 import { add0x, hexToNumber } from '@metamask/utils';
 import { Mutex } from 'async-mutex';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import { EventEmitter } from 'events';
 import { cloneDeep, mapValues, merge, pickBy, sortBy } from 'lodash';
 import { v1 as random } from 'uuid';

packages/transaction-controller/src/helpers/GasFeePoller.ts

@@ -6,6 +6,8 @@ import type {
 import type { NetworkClientId, Provider } from '@metamask/network-controller';
 import type { Hex } from '@metamask/utils';
 import { createModuleLogger } from '@metamask/utils';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 
 import { projectLogger } from '../logger';

packages/transaction-controller/src/helpers/IncomingTransactionHelper.ts

@@ -2,6 +2,8 @@ import type { AccountsController } from '@metamask/accounts-controller';
 import type { BlockTracker } from '@metamask/network-controller';
 import type { Hex } from '@metamask/utils';
 import { Mutex } from 'async-mutex';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 
 import {

packages/transaction-controller/src/helpers/MethodDataHelper.ts

@@ -2,6 +2,8 @@ import type { NetworkClientId, Provider } from '@metamask/network-controller';
 import { createModuleLogger } from '@metamask/utils';
 import { Mutex } from 'async-mutex';
 import { MethodRegistry } from 'eth-method-registry';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 
 import { projectLogger } from '../logger';

packages/transaction-controller/src/helpers/PendingTransactionTracker.ts

@@ -4,6 +4,8 @@ import type {
   BlockTracker,
   NetworkClientId,
 } from '@metamask/network-controller';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 import { cloneDeep, merge } from 'lodash';
 

packages/user-operation-controller/README.md

@@ -10,6 +10,10 @@ or
 
 `npm install @metamask/user-operation-controller`
 
+## Compatibility
+
+This package relies implicitly upon the `EventEmitter` module. This module is available natively in Node.js, but when using this package for the browser, make sure to use a polyfill such as `events`.
+
 ## Contributing
 
 This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).

packages/user-operation-controller/src/UserOperationController.ts

@@ -25,6 +25,8 @@ import {
   type TransactionType,
 } from '@metamask/transaction-controller';
 import { add0x } from '@metamask/utils';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 import type { Patch } from 'immer';
 import { cloneDeep } from 'lodash';

packages/user-operation-controller/src/helpers/PendingUserOperationTracker.ts

@@ -7,6 +7,8 @@ import type {
 } from '@metamask/network-controller';
 import { BlockTrackerPollingControllerOnly } from '@metamask/polling-controller';
 import { createModuleLogger, type Hex } from '@metamask/utils';
+// This package purposefully relies on Node's EventEmitter module.
+// eslint-disable-next-line import/no-nodejs-modules
 import EventEmitter from 'events';
 
 import { projectLogger } from '../logger';

scripts/create-package/utils.test.ts

@@ -14,6 +14,7 @@ jest.mock('fs', () => ({
     mkdir: jest.fn(),
     readFile: jest.fn(),
     writeFile: jest.fn(),
+    stat: jest.fn(),
   },
 }));
 
@@ -86,7 +87,9 @@ describe('create-package/utils', () => {
         nodeVersions: '>=18.0.0',
       };
 
-      (fs.existsSync as jest.Mock).mockReturnValueOnce(false);
+      (fs.promises.stat as jest.Mock).mockResolvedValueOnce({
+        isDirectory: () => false,
+      });
 
       (fsUtils.readAllFiles as jest.Mock).mockResolvedValueOnce({
         'src/index.ts': 'export default 42;',
@@ -167,7 +170,9 @@ describe('create-package/utils', () => {
         nodeVersions: '20.0.0',
       };
 
-      (fs.existsSync as jest.Mock).mockReturnValueOnce(true);
+      (fs.promises.stat as jest.Mock).mockResolvedValueOnce({
+        isDirectory: () => true,
+      });
 
       await expect(
         finalizeAndWriteData(packageData, monorepoFileData),