Add ESLint plugins for Jest, Jest DOM, and Testing Library

packages/eslint-config-react-app/index.js

@@ -112,6 +112,17 @@ module.exports = {
         '@typescript-eslint/no-useless-constructor': 'warn',
       },
     },
+    {
+      files: [
+        '**/__tests__/**/*.{js,jsx,ts,tsx}',
+        '**/*.{spec,test}.{js,jsx,ts,tsx}',
+      ],
+      extends: [
+        'plugin:jest/recommended',
+        'plugin:jest-dom/recommended',
+        'plugin:testing-library/react',
+      ],
+    },
   ],
 
   // NOTE: When adding rules here, you need to make sure they are compatible with

packages/eslint-config-react-app/package.json

@@ -21,9 +21,12 @@
     "eslint": "6.x",
     "eslint-plugin-flowtype": "3.x || 4.x",
     "eslint-plugin-import": "2.x",
+    "eslint-plugin-jest": "23.x",
+    "eslint-plugin-jest-dom": "2.x",
     "eslint-plugin-jsx-a11y": "6.x",
     "eslint-plugin-react": "7.x",
-    "eslint-plugin-react-hooks": "1.x || 2.x || 3.x || 4.x"
+    "eslint-plugin-react-hooks": "1.x || 2.x || 3.x || 4.x",
+    "eslint-plugin-testing-library": "2.x"
   },
   "dependencies": {
     "confusing-browser-globals": "^1.0.9"

packages/react-error-overlay/src/__tests__/extract-source-map.js

@@ -16,15 +16,8 @@ test('extracts last source map directive', async () => {
 });
 
 test('errors when no source map', async () => {
-  expect.assertions(1);
-
   const testFileName = 'test.js';
-  try {
-    await extractSourceMapUrl(
-      testFileName,
-      `console.log('hi')\n\nconsole.log('bye')`
-    );
-  } catch (e) {
-    expect(e).toBe(`Cannot find a source map directive for ${testFileName}.`);
-  }
+  await expect(
+    extractSourceMapUrl(testFileName, `console.log('hi')\n\nconsole.log('bye')`)
+  ).rejects.toBe(`Cannot find a source map directive for ${testFileName}.`);
 });

packages/react-error-overlay/src/__tests__/get-source-map.js

@@ -47,17 +47,10 @@ test('find an inline source map', async () => {
 });
 
 test('error on a source map with unsupported encoding', async () => {
-  expect.assertions(2);
-
   const file = fs
     .readFileSync(resolve(__dirname, '../../fixtures/junk-inline.mjs'))
     .toString('utf8');
-  try {
-    await getSourceMap('/', file);
-  } catch (e) {
-    expect(e instanceof Error).toBe(true);
-    expect(e.message).toBe(
-      'Sorry, non-base64 inline source-map encoding is not supported.'
-    );
-  }
+  await expect(getSourceMap('/', file)).rejects.toThrow(
+    new Error('Sorry, non-base64 inline source-map encoding is not supported.')
+  );
 });

packages/react-error-overlay/src/__tests__/parser/generic.js

@@ -8,23 +8,13 @@
 import { parse } from '../../utils/parser';
 
 test('throws on null', () => {
-  expect.assertions(2);
-  try {
-    parse(null);
-  } catch (e) {
-    expect(e instanceof Error).toBe(true);
-    expect(e.message).toBe('You cannot pass a null object.');
-  }
+  expect(() => parse(null)).toThrow(
+    new Error('You cannot pass a null object.')
+  );
 });
 
 test('throws on unparsable', () => {
-  expect.assertions(2);
-  try {
-    parse({});
-  } catch (e) {
-    expect(e instanceof Error).toBe(true);
-    expect(e.message).toBe(
-      'The error you provided does not contain a stack trace.'
-    );
-  }
+  expect(() => parse({})).toThrow(
+    new Error('The error you provided does not contain a stack trace.')
+  );
 });

packages/react-scripts/package.json

@@ -49,9 +49,12 @@
     "eslint-loader": "4.0.2",
     "eslint-plugin-flowtype": "4.7.0",
     "eslint-plugin-import": "2.20.2",
+    "eslint-plugin-jest": "23.6.0",
+    "eslint-plugin-jest-dom": "2.0.0",
     "eslint-plugin-jsx-a11y": "6.2.3",
     "eslint-plugin-react": "7.20.0",
     "eslint-plugin-react-hooks": "^4.0.0",
+    "eslint-plugin-testing-library": "2.2.1",
     "file-loader": "6.0.0",
     "fs-extra": "^9.0.0",
     "html-webpack-plugin": "4.3.0",