prefer-at: Support private field

rules/utils/is-same-reference.js

@@ -1,7 +1,7 @@
 'use strict';
 const {getStaticValue} = require('eslint-utils');
 
-// Copied from https://github.com/eslint/eslint/blob/c3e9accce2f61b04ab699fd37c90703305281aa3/lib/rules/utils/ast-utils.js#L379
+// Copied from https://github.com/eslint/eslint/blob/94ba68d76a6940f68ff82eea7332c6505f93df76/lib/rules/utils/ast-utils.js#L392
 
 /**
 Gets the property name of a given node.
@@ -128,7 +128,8 @@ function isSameReference(left, right) {
 			return true;
 		}
 
-		case 'Identifier': {
+		case 'Identifier':
+		case 'PrivateIdentifier': {
 			return left.name === right.name;
 		}
 
@@ -143,11 +144,23 @@ function isSameReference(left, right) {
 		case 'MemberExpression': {
 			const nameA = getStaticPropertyName(left);
 
-			// X.y = x["y"]
+			// `x.y = x["y"]`
+			if (typeof nameA !== 'undefined') {
+				return (
+					isSameReference(left.object, right.object)
+					&& nameA === getStaticPropertyName(right)
+				);
+			}
+
+			/*
+			`x[0] = x[0]`
+			`x[y] = x[y]`
+			`x.y = x.y`
+			*/
 			return (
-				typeof nameA !== 'undefined'
+				left.computed === right.computed
 				&& isSameReference(left.object, right.object)
-				&& nameA === getStaticPropertyName(right)
+				&& isSameReference(left.property, right.property)
 			);
 		}
 

test/no-array-push-push.mjs

@@ -209,9 +209,6 @@ test.snapshot({
 test({
 	valid: [
 		outdent`
-			a[x].push(1);
-			a[x].push(2);
-
 			'1'.someMagicPropertyReturnsAnArray.push(1);
 			(1).someMagicPropertyReturnsAnArray.push(2);
 
@@ -284,5 +281,15 @@ test({
 			`,
 			errors: 9,
 		},
+		{
+			code: outdent`
+				a[x].push(1);
+				a[x].push(2);
+			`,
+			output: outdent`
+				a[x].push(1, 2);
+			`,
+			errors: 1,
+		},
 	],
 });

test/prefer-at.mjs

@@ -18,6 +18,7 @@ test.snapshot({
 		'++ array[array.length - 1]',
 		'array[array.length - 1] --',
 		'delete array[array.length - 1]',
+		'class Foo {bar; #bar; baz() {return this.#bar[this.bar.length - 1]}}',
 	],
 	invalid: [
 		'array[array.length - 1];',
@@ -38,6 +39,8 @@ test.snapshot({
 		'const {a = array[array.length - 1]} = {}',
 		'typeof array[array.length - 1]',
 		'function foo() {return arguments[arguments.length - 1]}',
+		'class Foo {bar; baz() {return this.bar[this.bar.length - 1]}}',
+		'class Foo {#bar; baz() {return this.#bar[this.#bar.length - 1]}}',
 	],
 });
 

test/snapshots/prefer-at.mjs.md

@@ -286,6 +286,38 @@ Generated by [AVA](https://avajs.dev).
         |                                  ^^^^^^^^^^^^^^^^^^^^ Prefer \`.at(…)\` over \`[….length - index]\`.␊
     `
 
+## Invalid #19
+      1 | class Foo {bar; baz() {return this.bar[this.bar.length - 1]}}
+
+> Output
+
+    `␊
+      1 | class Foo {bar; baz() {return this.bar.at(-1)}}␊
+    `
+
+> Error 1/1
+
+    `␊
+    > 1 | class Foo {bar; baz() {return this.bar[this.bar.length - 1]}}␊
+        |                                        ^^^^^^^^^^^^^^^^^^^ Prefer \`.at(…)\` over \`[….length - index]\`.␊
+    `
+
+## Invalid #20
+      1 | class Foo {#bar; baz() {return this.#bar[this.#bar.length - 1]}}
+
+> Output
+
+    `␊
+      1 | class Foo {#bar; baz() {return this.#bar.at(-1)}}␊
+    `
+
+> Error 1/1
+
+    `␊
+    > 1 | class Foo {#bar; baz() {return this.#bar[this.#bar.length - 1]}}␊
+        |                                          ^^^^^^^^^^^^^^^^^^^^ Prefer \`.at(…)\` over \`[….length - index]\`.␊
+    `
+
 ## Invalid #1
       1 | string.charAt(string.length - 1);