Enable Jest ESLint plugin with recommended config

Author: alexeyr

eslint.config.ts

@@ -1,5 +1,6 @@
 import path from 'node:path';
 import { globalIgnores } from 'eslint/config';
+import jest from 'eslint-plugin-jest';
 import prettierRecommended from 'eslint-plugin-prettier/recommended';
 import globals from 'globals';
 import tsEslint from 'typescript-eslint';
@@ -52,10 +53,6 @@ const config = tsEslint.config([
       globals: {
         ...globals.browser,
         ...globals.node,
-        ...globals.mocha,
-        ...globals.jest,
-        __DEBUG_SERVER_ERRORS__: true,
-        __SERVER_ERRORS__: true,
       },
 
       parserOptions: {
@@ -190,6 +187,16 @@ const config = tsEslint.config([
       'react/no-deprecated': 'off',
     },
   },
+  {
+    files: ['node_package/tests/**', '**/*.test.{js,jsx,ts,tsx}'],
+
+    extends: [jest.configs['flat/recommended'], jest.configs['flat/style']],
+
+    rules: {
+      // Allows Jest mocks before import
+      'import/first': 'off',
+    },
+  },
   // must be the last config in the array
   // https://github.com/prettier/eslint-plugin-prettier?tab=readme-ov-file#configuration-new-eslintconfigjs
   prettierRecommended,

node_package/tests/Authenticity.test.js

@@ -8,10 +8,9 @@ meta.content = testToken;
 document.head.appendChild(meta);
 
 describe('authenticityToken', () => {
-  expect.assertions(2);
   it('exists in ReactOnRails API', () => {
     expect.assertions(1);
-    expect(typeof ReactOnRails.authenticityToken).toEqual('function');
+    expect(typeof ReactOnRails.authenticityToken).toBe('function');
   });
 
   it('can read Rails CSRF token from <meta>', () => {
@@ -22,10 +21,9 @@ describe('authenticityToken', () => {
 });
 
 describe('authenticityHeaders', () => {
-  expect.assertions(2);
   it('exists in ReactOnRails API', () => {
     expect.assertions(1);
-    expect(typeof ReactOnRails.authenticityHeaders).toEqual('function');
+    expect(typeof ReactOnRails.authenticityHeaders).toBe('function');
   });
 
   it('returns valid header with CSRF token', () => {

node_package/tests/ComponentRegistry.test.js

@@ -176,10 +176,12 @@ describe('ComponentRegistry', () => {
 
   it('handles timeout for unregistered components', async () => {
     expect.assertions(1);
+    let error;
     try {
       await ComponentRegistry.getOrWaitForComponent('NonExistent');
-    } catch (error) {
-      expect(error.message).toMatch(/Could not find component/);
+    } catch (e) {
+      error = e;
     }
+    expect(error.message).toMatch(/Could not find component/);
   });
 });

node_package/tests/ReactOnRails.test.jsx

@@ -7,7 +7,6 @@ import * as createReactClass from 'create-react-class';
 import ReactOnRails from '../src/ReactOnRails.client.ts';
 
 describe('ReactOnRails', () => {
-  expect.assertions(14);
   it('render returns a virtual DOM element for component', () => {
     expect.assertions(1);
     const R1 = createReactClass({
@@ -25,7 +24,7 @@ describe('ReactOnRails', () => {
     document.body.appendChild(root);
     ReactOnRails.render('R1', {}, 'root');
 
-    expect(document.getElementById('root').textContent).toEqual(' WORLD ');
+    expect(document.getElementById('root').textContent).toBe(' WORLD ');
   });
 
   it('accepts traceTurbolinks as an option true', () => {

node_package/tests/StoreRegistry.test.js

@@ -14,11 +14,13 @@ function storeGenerator2(props) {
   return createStore(reducer, props);
 }
 
-describe('', () => {
-  expect.assertions(11);
+describe('StoreRegistry', () => {
+  beforeEach(() => {
+    StoreRegistry.stores().clear();
+  });
+
   it('StoreRegistry throws error for registering null or undefined store', () => {
     expect.assertions(2);
-    StoreRegistry.stores().clear();
     expect(() => StoreRegistry.register({ storeGenerator: null })).toThrow(
       /Called ReactOnRails.registerStoreGenerators with a null or undefined as a value/,
     );
@@ -29,7 +31,6 @@ describe('', () => {
 
   it('StoreRegistry throws error for retrieving unregistered store', () => {
     expect.assertions(1);
-    StoreRegistry.stores().clear();
     expect(() => StoreRegistry.getStore('foobar')).toThrow(
       /There are no stores hydrated and you are requesting the store/,
     );
@@ -46,7 +47,7 @@ describe('', () => {
     expect(actual2).toEqual(expected2);
   });
 
-  it('StoreRegistry throws error for retrieving unregistered store', () => {
+  it('StoreRegistry throws error for retrieving unregistered store generator', () => {
     expect.assertions(1);
     expect(() => StoreRegistry.getStoreGenerator('foobar')).toThrow(
       /Could not find store generator registered with name foobar\. Registered store generator names include/,

node_package/tests/buildConsoleReplay.test.js

@@ -1,7 +1,6 @@
 import buildConsoleReplay, { consoleReplay } from '../src/buildConsoleReplay.ts';
 
 describe('consoleReplay', () => {
-  expect.assertions(8);
   it('does not throw an exception if no console.history object', () => {
     expect.assertions(1);
     expect(() => consoleReplay()).not.toThrow(/Error/);
@@ -14,13 +13,7 @@ describe('consoleReplay', () => {
     expect(actual).toEqual(expected);
   });
 
-  it('does not throw an exception if console.history.length is zero', () => {
-    expect.assertions(1);
-    console.history = [];
-    expect(() => consoleReplay()).not.toThrow(/Error/);
-  });
-
-  it('returns empty string if no console.history object', () => {
+  it('returns empty string if console.history is empty', () => {
     expect.assertions(1);
     console.history = [];
     const actual = consoleReplay();
@@ -52,7 +45,7 @@ console.warn.apply(console, ["other message","{\\"c\\":3,\\"d\\":4}"]);`;
     expect(actual).toEqual(expected);
   });
 
-  it('replays converts script tag inside of object string to be safe ', () => {
+  it('replays converts script tag inside of object string to be safe', () => {
     expect.assertions(1);
     console.history = [
       {

node_package/tests/renderFunction.test.jsx

@@ -8,7 +8,6 @@ import * as createReactClass from 'create-react-class';
 import isRenderFunction from '../src/isRenderFunction.ts';
 
 describe('isRenderFunction', () => {
-  expect.assertions(6);
   it('returns false for a ES5 React Component', () => {
     expect.assertions(1);
 

node_package/tests/scriptSanitizedVal.test.js

@@ -1,7 +1,6 @@
 import scriptSanitizedVal from '../src/scriptSanitizedVal.ts';
 
 describe('scriptSanitizedVal', () => {
-  expect.assertions(5);
   it('returns no </script if spaces, uppercase 1', () => {
     expect.assertions(1);
     const input = '[SERVER] This is a script:"</div>"</script> <script>alert(\'WTF\')</  SCRIPT >';

node_package/tests/serverRenderReactComponent.test.ts

@@ -245,7 +245,7 @@ describe('serverRenderReactComponent', () => {
     });
     assertIsPromise(renderResult);
     const result = await renderResult;
-    expect(result.html).toEqual('<div>Hello</div>');
+    expect(result.html).toBe('<div>Hello</div>');
   });
 
   it('serverRenderReactComponent renders an error if attempting to render a renderer', () => {

package.json

@@ -39,11 +39,12 @@
     "eslint-config-shakacode": "^19.0.0",
     "eslint-import-resolver-alias": "^1.1.2",
     "eslint-plugin-import": "^2.31.0",
+    "eslint-plugin-jest": "^28.11.0",
     "eslint-plugin-jsx-a11y": "^6.10.2",
     "eslint-plugin-prettier": "^5.2.3",
     "eslint-plugin-react": "^7.37.4",
     "eslint-plugin-react-hooks": "^5.2.0",
-    "typescript-eslint": "^8.26.1",
+    "typescript-eslint": "^8.29.1",
     "globals": "^16.0.0",
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",