[PATCH] [10.x] Fix ESLint 6.2.0 + babel-eslint + no-unused-vars false positive with for-in loop

.eslintrc.js

@@ -1,16 +1,21 @@
+"use strict";
+
+const config = require("eslint-config-babel");
+
 module.exports = {
   root: true,
-  extends: "babel",
-  "plugins": [
-    "prettier"
-  ],
-  rules: {
+  parser: "./lib",
+  extends: config.extends,
+  plugins: config.plugins.concat(["prettier"]),
+  rules: Object.assign(config.rules, {
     "no-var": 0,
     "max-len": 0,
     "prettier/prettier": "error",
-  },
-  env: {
+  }),
+  env: Object.assign(config.env, {
     node: true,
-    mocha: true
-  }
+    mocha: true,
+  }),
+  parserOptions: config.parserOptions,
+  globals: config.globals,
 };

.prettierrc

@@ -1,3 +1,3 @@
 {
-    "trailingComma": "es5"
-  }
+  "trailingComma": "es5"
+}

lib/parse.js

@@ -11,7 +11,9 @@ module.exports = function(code, options) {
     options.ecmaFeatures && options.ecmaFeatures.legacyDecorators;
 
   var opts = {
-    codeFrame: options.hasOwnProperty("codeFrame") ? options.codeFrame : true,
+    codeFrame: Object.prototype.hasOwnProperty.call(options, "codeFrame")
+      ? options.codeFrame
+      : true,
     sourceType: options.sourceType,
     allowImportExportEverywhere: options.allowImportExportEverywhere, // consistent with espree
     allowReturnOutsideFunction: true,

package.json

@@ -15,7 +15,6 @@
     "@babel/parser": "^7.0.0",
     "@babel/traverse": "^7.0.0",
     "@babel/types": "^7.0.0",
-    "eslint-scope": "3.7.1",
     "eslint-visitor-keys": "^1.0.0"
   },
   "scripts": {
@@ -37,12 +36,12 @@
   },
   "homepage": "https://github.com/babel/babel-eslint",
   "peerDependencies": {
-    "eslint": ">= 4.12.1"
+    "eslint": ">= 4.12.1",
+    "eslint-scope": "^3.7.1 || ^4.0.0 || ^5.0.0"
   },
   "devDependencies": {
-    "babel-eslint": "^8.2.6",
     "dedent": "^0.7.0",
-    "eslint": "^5.6.0",
+    "eslint": "~5.4.0",
     "eslint-config-babel": "^7.0.1",
     "eslint-plugin-flowtype": "^2.30.3",
     "eslint-plugin-import": "^2.14.0",

test/babel-eslint.js

@@ -261,11 +261,11 @@ describe("babylon-to-espree", () => {
   });
 
   it("export named", () => {
-    parseAndAssertSame("export { foo };");
+    parseAndAssertSame("var foo = 1;export { foo };");
   });
 
   it("export named alias", () => {
-    parseAndAssertSame("export { foo as bar };");
+    parseAndAssertSame("var foo = 1;export { foo as bar };");
   });
 
   // Espree doesn't support the optional chaining operator yet
@@ -470,10 +470,6 @@ describe("babylon-to-espree", () => {
       parseAndAssertSame("return;");
     });
 
-    it("super outside method", () => {
-      parseAndAssertSame("function F() { super(); }");
-    });
-
     it("StringLiteral", () => {
       parseAndAssertSame("");
       parseAndAssertSame("");

test/integration.js

@@ -3,6 +3,10 @@ var eslint = require("eslint");
 var fs = require("fs");
 var path = require("path");
 
+var parser = require("../lib");
+
+eslint.linter.defineParser("current-babel-eslint", parser);
+
 var paths = {
   fixtures: path.join(__dirname, "fixtures", "rules"),
 };
@@ -11,7 +15,7 @@ var encoding = "utf8";
 var errorLevel = 2;
 
 var baseEslintOpts = {
-  parser: require.resolve(".."),
+  parser: "current-babel-eslint",
   parserOptions: {
     sourceType: "script",
   },
@@ -281,3 +285,30 @@ function strictSuite() {
     });
   });
 }
+
+describe("no-unused-vars", () => {
+  const ruleId = "no-unused-vars";
+  const eslintOpts = Object.assign({}, baseEslintOpts, {
+    rules: {},
+  });
+  eslintOpts.rules[ruleId] = [errorLevel, "never"];
+
+  it("should not detect false positives inside for loop", () => {
+    const src =
+      "const nodeList = []; const visit = () => {}; for (const node of nodeList) { visit(node); }";
+
+    const report = eslint.linter.verify(src, eslintOpts);
+
+    assert(report.length === 0);
+  });
+
+  it("should detect unused var inside for loop", () => {
+    const src =
+      "const nodeList = []; const visit = () => {}; for (const node of nodeList) { visit(); }";
+
+    const report = eslint.linter.verify(src, eslintOpts);
+
+    assert(report.length === 1);
+    assert(report[0].ruleId === ruleId);
+  });
+});

test/non-regression.js

@@ -3,6 +3,8 @@
 var eslint = require("eslint");
 var unpad = require("dedent");
 
+var parser = require("../lib");
+
 function verifyAndAssertMessagesWithSpecificESLint(
   code,
   rules,
@@ -12,7 +14,7 @@ function verifyAndAssertMessagesWithSpecificESLint(
   linter
 ) {
   var config = {
-    parser: require.resolve(".."),
+    parser: "current-babel-eslint",
     rules,
     env: {
       node: true,
@@ -68,13 +70,16 @@ function verifyAndAssertMessages(
   sourceType,
   overrideConfig
 ) {
+  var linter = new eslint.Linter();
+  linter.defineParser("current-babel-eslint", parser);
+
   verifyAndAssertMessagesWithSpecificESLint(
     unpad(`${code}`),
     rules || {},
     expectedMessages || [],
     sourceType,
     overrideConfig,
-    new eslint.Linter()
+    linter
   );
 }