Enable Jest ESLint plugin with recommended config

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: {
@@ -178,6 +175,16 @@ const config = tsEslint.config([
       '@typescript-eslint/restrict-template-expressions': '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

@@ -8,28 +8,22 @@ 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>', () => {
-    expect.assertions(1);
     const realToken = ReactOnRails.authenticityToken();
     expect(realToken).toEqual(testToken);
   });
 });
 
 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', () => {
-    expect.assertions(1);
     const realHeader = ReactOnRails.authenticityHeaders();
     expect(realHeader).toEqual({ 'X-CSRF-Token': testToken, 'X-Requested-With': 'XMLHttpRequest' });
   });

node_package/tests/ComponentRegistry.test.js

@@ -37,7 +37,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('registers and retrieves React function components', () => {
-    expect.assertions(1);
     const C1 = () => <div>HELLO</div>;
     ComponentRegistry.register({ C1 });
     const actual = ComponentRegistry.get('C1');
@@ -46,7 +45,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('registers and retrieves Render-Function components where property renderFunction is set and zero params', () => {
-    expect.assertions(1);
     const C1 = () => <div>HELLO</div>;
     C1.renderFunction = true;
     ComponentRegistry.register({ C1 });
@@ -56,7 +54,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('registers and retrieves ES5 class components', () => {
-    expect.assertions(1);
     const C2 = createReactClass({
       render() {
         return <div> WORLD </div>;
@@ -69,7 +66,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('registers and retrieves ES6 class components', () => {
-    expect.assertions(1);
     class C3 extends React.Component {
       render() {
         return <div>Wow!</div>;
@@ -82,7 +78,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('registers and retrieves renderers if 3 params', () => {
-    expect.assertions(1);
     const C4 = (a1, a2, a3) => null;
     ComponentRegistry.register({ C4 });
     const actual = ComponentRegistry.get('C4');
@@ -95,7 +90,6 @@ describe('ComponentRegistry', () => {
    * Thus, tests are cumulative.
    */
   it('registers and retrieves multiple components', () => {
-    expect.assertions(4);
     // Plain react stateless functional components
     const C5 = () => <div>WHY</div>;
     const C6 = () => <div>NOW</div>;
@@ -127,7 +121,6 @@ describe('ComponentRegistry', () => {
   });
 
   it('only detects a renderer function if it has three arguments', () => {
-    expect.assertions(2);
     const C7 = (a1, a2) => null;
     const C8 = (a1) => null;
     ComponentRegistry.register({ C7 });
@@ -148,20 +141,17 @@ describe('ComponentRegistry', () => {
   });
 
   it('throws error for retrieving unregistered component', () => {
-    expect.assertions(1);
     expect(() => ComponentRegistry.get('foobar')).toThrow(
       /Could not find component registered with name foobar/,
     );
   });
 
   it('throws error for setting null component', () => {
-    expect.assertions(1);
     const C9 = null;
     expect(() => ComponentRegistry.register({ C9 })).toThrow(/Called register with null component named C9/);
   });
 
   it('retrieves component asynchronously when registered later', async () => {
-    expect.assertions(1);
     const C1 = () => <div>HELLO</div>;
     const componentPromise = ComponentRegistry.getOrWaitForComponent('C1');
     ComponentRegistry.register({ C1 });
@@ -175,11 +165,12 @@ 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

@@ -7,9 +7,7 @@ import * as createReactClass from 'create-react-class';
 import ReactOnRails from '../src/ReactOnRails.client';
 
 describe('ReactOnRails', () => {
-  expect.assertions(14);
   it('render returns a virtual DOM element for component', () => {
-    expect.assertions(1);
     const R1 = createReactClass({
       render() {
         return <div> WORLD </div>;
@@ -25,42 +23,36 @@ 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', () => {
     ReactOnRails.resetOptions();
-    expect.assertions(1);
     ReactOnRails.setOptions({ traceTurbolinks: true });
     const actual = ReactOnRails.option('traceTurbolinks');
     expect(actual).toBe(true);
   });
 
   it('accepts traceTurbolinks as an option false', () => {
     ReactOnRails.resetOptions();
-    expect.assertions(1);
     ReactOnRails.setOptions({ traceTurbolinks: false });
     const actual = ReactOnRails.option('traceTurbolinks');
     expect(actual).toBe(false);
   });
 
   it('not specified has traceTurbolinks as false', () => {
     ReactOnRails.resetOptions();
-    expect.assertions(1);
     ReactOnRails.setOptions({});
     const actual = ReactOnRails.option('traceTurbolinks');
     expect(actual).toBe(false);
   });
 
   it('setOptions method throws error for invalid options', () => {
     ReactOnRails.resetOptions();
-    expect.assertions(1);
     expect(() => ReactOnRails.setOptions({ foobar: true })).toThrow(/Invalid option/);
   });
 
   it('registerStore throws if passed a falsey object (null, undefined, etc)', () => {
-    expect.assertions(3);
-
     expect(() => ReactOnRails.registerStore(null)).toThrow(/null or undefined/);
 
     expect(() => ReactOnRails.registerStore(undefined)).toThrow(/null or undefined/);
@@ -69,7 +61,6 @@ describe('ReactOnRails', () => {
   });
 
   it('register store and getStoreGenerator allow registration', () => {
-    expect.assertions(2);
     function reducer() {
       return {};
     }
@@ -87,7 +78,6 @@ describe('ReactOnRails', () => {
   });
 
   it('setStore and getStore', () => {
-    expect.assertions(2);
     function reducer() {
       return {};
     }
@@ -109,7 +99,6 @@ describe('ReactOnRails', () => {
   });
 
   it('clearHydratedStores', () => {
-    expect.assertions(2);
     function reducer() {
       return {};
     }

node_package/tests/StoreRegistry.test.js

@@ -14,11 +14,12 @@ function storeGenerator2(props) {
   return createStore(reducer, props);
 }
 
-describe('', () => {
-  expect.assertions(11);
-  it('StoreRegistry throws error for registering null or undefined store', () => {
-    expect.assertions(2);
+describe('StoreRegistry', () => {
+  beforeEach(() => {
     StoreRegistry.stores().clear();
+  });
+
+  it('StoreRegistry throws error for registering null or undefined store', () => {
     expect(() => StoreRegistry.register({ storeGenerator: null })).toThrow(
       /Called ReactOnRails.registerStoreGenerators with a null or undefined as a value/,
     );
@@ -28,15 +29,12 @@ 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/,
     );
   });
 
   it('StoreRegistry registers and retrieves Render-Function stores', () => {
-    expect.assertions(2);
     StoreRegistry.register({ storeGenerator, storeGenerator2 });
     const actual = StoreRegistry.getStoreGenerator('storeGenerator');
     const expected = storeGenerator;
@@ -46,23 +44,20 @@ describe('', () => {
     expect(actual2).toEqual(expected2);
   });
 
-  it('StoreRegistry throws error for retrieving unregistered store', () => {
-    expect.assertions(1);
+  it('StoreRegistry throws error for retrieving unregistered store generator', () => {
     expect(() => StoreRegistry.getStoreGenerator('foobar')).toThrow(
       /Could not find store generator registered with name foobar\. Registered store generator names include/,
     );
   });
 
   it('StoreRegistry returns undefined for retrieving unregistered store, passing throwIfMissing = false', () => {
-    expect.assertions(1);
     StoreRegistry.setStore('foobarX', {});
     const actual = StoreRegistry.getStore('foobar', false);
     const expected = undefined;
     expect(actual).toEqual(expected);
   });
 
   it('StoreRegistry getStore, setStore', () => {
-    expect.assertions(1);
     const store = storeGenerator({});
     StoreRegistry.setStore('storeGenerator', store);
     const actual = StoreRegistry.getStore('storeGenerator');
@@ -71,14 +66,12 @@ describe('', () => {
   });
 
   it('StoreRegistry throws error for retrieving unregistered hydrated store', () => {
-    expect.assertions(1);
     expect(() => StoreRegistry.getStore('foobar')).toThrow(
       /Could not find hydrated store registered with name foobar\. Registered hydrated store names include/,
     );
   });
 
   it('StoreRegistry clearHydratedStores', () => {
-    expect.assertions(2);
     StoreRegistry.clearHydratedStores();
 
     const result = storeGenerator({});

node_package/tests/buildConsoleReplay.test.js

@@ -1,35 +1,24 @@
 import buildConsoleReplay, { consoleReplay } from '../src/buildConsoleReplay';
 
 describe('consoleReplay', () => {
-  expect.assertions(8);
   it('does not throw an exception if no console.history object', () => {
-    expect.assertions(1);
     expect(() => consoleReplay()).not.toThrow(/Error/);
   });
 
   it('returns empty string if no console.history object', () => {
-    expect.assertions(1);
     const actual = consoleReplay();
     const expected = '';
     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', () => {
-    expect.assertions(1);
+  it('returns empty string if console.history is empty', () => {
     console.history = [];
     const actual = consoleReplay();
     const expected = '';
     expect(actual).toEqual(expected);
   });
 
   it('replays multiple history messages', () => {
-    expect.assertions(1);
     console.history = [
       { arguments: ['a', 'b'], level: 'log' },
       { arguments: ['c', 'd'], level: 'warn' },
@@ -40,7 +29,6 @@ describe('consoleReplay', () => {
   });
 
   it('replays converts console param objects to JSON', () => {
-    expect.assertions(1);
     console.history = [
       { arguments: ['some message', { a: 1, b: 2 }], level: 'log' },
       { arguments: ['other message', { c: 3, d: 4 }], level: 'warn' },
@@ -52,8 +40,7 @@ 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 ', () => {
-    expect.assertions(1);
+  it('replays converts script tag inside of object string to be safe', () => {
     console.history = [
       {
         arguments: [
@@ -74,7 +61,6 @@ console.warn.apply(console, ["other message","{\\"c\\":3,\\"d\\":4}"]);`;
   });
 
   it('buildConsoleReplay wraps console replay in a script tag', () => {
-    expect.assertions(1);
     console.history = [
       { arguments: ['some message', { a: 1, b: 2 }], level: 'log' },
       { arguments: ['other message', { c: 3, d: 4 }], level: 'warn' },