From 676bb772a7805abd3239fb464d8f66fa6d61ce8d Mon Sep 17 00:00:00 2001
From: Roberto Cestari <robertotcestari@gmail.com>
Date: Tue, 26 Apr 2022 19:10:26 -0300
Subject: [PATCH] fix: add support for private and public class fields from
 es2022

---
 lib/rules/no-underscore-dangle.js       | 24 ++++++++++++++++++++-
 tests/lib/rules/no-underscore-dangle.js | 28 ++++++++++++++++++++++---
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/lib/rules/no-underscore-dangle.js b/lib/rules/no-underscore-dangle.js
index 0ab41feb03c..4da037b3b2e 100644
--- a/lib/rules/no-underscore-dangle.js
+++ b/lib/rules/no-underscore-dangle.js
@@ -261,6 +261,28 @@ module.exports = {
             }
         }
 
+        /**
+         * Check if property declaration has a dangling underscore
+         * @param {ASTNode} node node to evaluate
+         * @returns {void}
+         * @private
+         */
+        function checkForDanglingUnderscoreInClassProperty(node) {
+            const identifier = node.key.name;
+            const isProperty = node.type === "PropertyDefinition";
+
+            if (typeof identifier !== "undefined" && hasDanglingUnderscore(identifier) && isProperty && !isAllowed(identifier)) {
+                context.report({
+                    node,
+                    messageId: "unexpectedUnderscore",
+                    data: {
+                        identifier
+                    }
+                });
+            }
+        }
+
+
         //--------------------------------------------------------------------------
         // Public API
         //--------------------------------------------------------------------------
@@ -270,7 +292,7 @@ module.exports = {
             VariableDeclarator: checkForDanglingUnderscoreInVariableExpression,
             MemberExpression: checkForDanglingUnderscoreInMemberExpression,
             MethodDefinition: checkForDanglingUnderscoreInMethod,
-            PropertyDefinition: checkForDanglingUnderscoreInMethod,
+            PropertyDefinition: checkForDanglingUnderscoreInClassProperty,
             Property: checkForDanglingUnderscoreInMethod,
             FunctionExpression: checkForDanglingUnderscoreInFunction,
             ArrowFunctionExpression: checkForDanglingUnderscoreInFunction
diff --git a/tests/lib/rules/no-underscore-dangle.js b/tests/lib/rules/no-underscore-dangle.js
index c83a5b3fe28..2571f062370 100644
--- a/tests/lib/rules/no-underscore-dangle.js
+++ b/tests/lib/rules/no-underscore-dangle.js
@@ -69,9 +69,7 @@ ruleTester.run("no-underscore-dangle", rule, {
         { code: "function foo([_bar] = []) {}", options: [{ allowFunctionParams: false }], parserOptions: { ecmaVersion: 6 } },
         { code: "function foo( { _bar }) {}", options: [{ allowFunctionParams: false }], parserOptions: { ecmaVersion: 6 } },
         { code: "function foo( { _bar = 0 } = {}) {}", options: [{ allowFunctionParams: false }], parserOptions: { ecmaVersion: 6 } },
-        { code: "function foo(...[_bar]) {}", options: [{ allowFunctionParams: false }], parserOptions: { ecmaVersion: 2016 } },
-        { code: "class foo { _field; }", parserOptions: { ecmaVersion: 2022 } },
-        { code: "class foo { #_field; }", parserOptions: { ecmaVersion: 2022 } }
+        { code: "function foo(...[_bar]) {}", options: [{ allowFunctionParams: false }], parserOptions: { ecmaVersion: 2016 } }
     ],
     invalid: [
         { code: "var _foo = 1", errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "_foo" }, type: "VariableDeclarator" }] },
@@ -109,6 +107,30 @@ ruleTester.run("no-underscore-dangle", rule, {
             options: [{ enforceInMethodNames: true }],
             parserOptions: { ecmaVersion: 2022 },
             errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "#bar_" } }]
+        },
+        {
+            code: "class foo { _field; }",
+            options: [{ enforceInMethodNames: true }],
+            parserOptions: { ecmaVersion: 2022 },
+            errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "_field" } }]
+        },
+        {
+            code: "class foo { #_field; }",
+            options: [{ enforceInMethodNames: true }],
+            parserOptions: { ecmaVersion: 2022 },
+            errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "_field" } }]
+        },
+        {
+            code: "class foo { field_; }",
+            options: [{ enforceInMethodNames: true }],
+            parserOptions: { ecmaVersion: 2022 },
+            errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "field_" } }]
+        },
+        {
+            code: "class foo { #field_; }",
+            options: [{ enforceInMethodNames: true }],
+            parserOptions: { ecmaVersion: 2022 },
+            errors: [{ messageId: "unexpectedUnderscore", data: { identifier: "field_" } }]
         }
     ]
 });