Add ESLint 6 support

Author: mrmckeb

package.json

@@ -19,7 +19,7 @@
     "compile:lockfile": "node tasks/compile-lockfile.js"
   },
   "devDependencies": {
-    "eslint": "5.16.0",
+    "eslint": "6.1.0",
     "execa": "1.0.0",
     "fs-extra": "^7.0.1",
     "get-port": "^4.2.0",

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

@@ -163,7 +163,9 @@ module.exports = {
     'no-obj-calls': 'warn',
     'no-octal': 'warn',
     'no-octal-escape': 'warn',
-    'no-redeclare': 'warn',
+    // TODO: Remove this option in the next major release of CRA.
+    // https://eslint.org/docs/user-guide/migrating-to-6.0.0#-the-no-redeclare-rule-is-now-more-strict-by-default
+    'no-redeclare': ['warn', { builtinGlobals: false }],
     'no-regex-spaces': 'warn',
     'no-restricted-syntax': ['warn', 'WithStatement'],
     'no-script-url': 'warn',

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

@@ -18,8 +18,8 @@
     "@typescript-eslint/eslint-plugin": "1.x",
     "@typescript-eslint/parser": "1.x",
     "babel-eslint": "10.x",
-    "eslint": "5.x",
-    "eslint-plugin-flowtype": "2.x",
+    "eslint": "6.x",
+    "eslint-plugin-flowtype": "3.x",
     "eslint-plugin-import": "2.x",
     "eslint-plugin-jsx-a11y": "6.x",
     "eslint-plugin-react": "7.x",

packages/react-error-overlay/package.json

@@ -37,19 +37,19 @@
     "@babel/code-frame": "7.0.0",
     "@babel/core": "7.4.3",
     "anser": "1.4.8",
-    "babel-eslint": "10.0.1",
+    "babel-eslint": "10.0.2",
     "babel-jest": "^24.8.0",
     "babel-loader": "8.0.5",
     "babel-preset-react-app": "^9.0.0",
     "chalk": "^2.4.2",
     "chokidar": "^2.1.2",
     "cross-env": "5.2.0",
-    "eslint": "^5.16.0",
+    "eslint": "^6.1.0",
     "eslint-config-react-app": "^4.0.1",
-    "eslint-plugin-flowtype": "2.50.1",
-    "eslint-plugin-import": "2.16.0",
-    "eslint-plugin-jsx-a11y": "6.2.1",
-    "eslint-plugin-react": "7.12.4",
+    "eslint-plugin-flowtype": "3.12.1",
+    "eslint-plugin-import": "2.18.2",
+    "eslint-plugin-jsx-a11y": "6.2.3",
+    "eslint-plugin-react": "7.14.3",
     "flow-bin": "^0.63.1",
     "html-entities": "1.2.1",
     "jest": "24.7.1",

packages/react-scripts/package.json

@@ -30,9 +30,9 @@
   "dependencies": {
     "@babel/core": "7.4.3",
     "@svgr/webpack": "4.3.1",
-    "@typescript-eslint/eslint-plugin": "1.10.2",
-    "@typescript-eslint/parser": "1.10.2",
-    "babel-eslint": "10.0.1",
+    "@typescript-eslint/eslint-plugin": "1.13.0",
+    "@typescript-eslint/parser": "1.13.0",
+    "babel-eslint": "10.0.2",
     "babel-jest": "^24.8.0",
     "babel-loader": "8.0.5",
     "babel-plugin-named-asset-import": "^0.3.2",
@@ -42,14 +42,14 @@
     "css-loader": "2.1.1",
     "dotenv": "6.2.0",
     "dotenv-expand": "4.2.0",
-    "eslint": "^5.16.0",
+    "eslint": "^6.1.0",
     "eslint-config-react-app": "^4.0.1",
-    "eslint-loader": "2.1.2",
-    "eslint-plugin-flowtype": "2.50.1",
-    "eslint-plugin-import": "2.16.0",
-    "eslint-plugin-jsx-a11y": "6.2.1",
-    "eslint-plugin-react": "7.12.4",
-    "eslint-plugin-react-hooks": "^1.5.0",
+    "eslint-loader": "2.2.1",
+    "eslint-plugin-flowtype": "3.12.1",
+    "eslint-plugin-import": "2.18.2",
+    "eslint-plugin-jsx-a11y": "6.2.3",
+    "eslint-plugin-react": "7.14.3",
+    "eslint-plugin-react-hooks": "^1.6.1",
     "file-loader": "3.0.1",
     "fs-extra": "7.0.1",
     "html-webpack-plugin": "4.0.0-beta.5",

packages/react-scripts/scripts/utils/createJestConfig.js

@@ -84,15 +84,15 @@ module.exports = (resolve, rootDir, isEjecting) => {
   ];
   if (overrides) {
     supportedKeys.forEach(key => {
-      if (overrides.hasOwnProperty(key)) {
-        if (Array.isArray(config[key]) || typeof config[key] !== 'object')  {
+      if (Object.prototype.hasOwnProperty.call(overrides, key)) {
+        if (Array.isArray(config[key]) || typeof config[key] !== 'object') {
           // for arrays or primitive types, directly override the config key
-          config[key] = overrides[key];  
+          config[key] = overrides[key];
         } else {
           // for object types, extend gracefully
-          config[key] = Object.assign({}, config[key], overrides[key]);  
-        } 
-        
+          config[key] = Object.assign({}, config[key], overrides[key]);
+        }
+
         delete overrides[key];
       }
     });