feat(eslint-plugin-template): [no-duplicate-attributes] Add option to ignore properties

packages/eslint-plugin-template/docs/rules/no-duplicate-attributes.md

@@ -35,6 +35,12 @@ interface Options {
    * Default: `true`
    */
   allowTwoWayDataBinding?: boolean;
+  /**
+   * Input or output properties for which duplicate presence is allowed as an exception to the rule.
+   *
+   * Default: `[]`
+   */
+  ignore?: string[];
 }
 
 ```
@@ -346,6 +352,38 @@ interface Options {
        ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ```
 
+<br>
+
+---
+
+<br>
+
+#### Custom Config
+
+```json
+{
+  "rules": {
+    "@angular-eslint/template/no-duplicate-attributes": [
+      "error",
+      {
+        "ignore": [
+          "class"
+        ]
+      }
+    ]
+  }
+}
+```
+
+<br>
+
+#### ❌ Invalid Code
+
+```html
+<input [name]="foo" class="css-static" name="bar" [class]="dynamic">
+       ~~~~~~~~~~~~                    ~~~~~~~~~~
+```
+
 </details>
 
 <br>

packages/eslint-plugin-template/src/rules/no-duplicate-attributes.ts

@@ -10,10 +10,18 @@ import {
 } from '../utils/create-eslint-rule';
 import { getOriginalAttributeName } from '../utils/get-original-attribute-name';
 
-type Options = [{ readonly allowTwoWayDataBinding?: boolean }];
+type Options = [
+  {
+    readonly allowTwoWayDataBinding?: boolean;
+    readonly ignore?: readonly string[];
+  },
+];
 export type MessageIds = 'noDuplicateAttributes' | 'suggestRemoveAttribute';
 export const RULE_NAME = 'no-duplicate-attributes';
-const DEFAULT_OPTIONS: Options[number] = { allowTwoWayDataBinding: true };
+const DEFAULT_OPTIONS: Options[number] = {
+  allowTwoWayDataBinding: true,
+  ignore: [],
+};
 
 export default createESLintRule<Options, MessageIds>({
   name: RULE_NAME,
@@ -34,6 +42,13 @@ export default createESLintRule<Options, MessageIds>({
             default: DEFAULT_OPTIONS.allowTwoWayDataBinding,
             description: `Whether or not two-way data binding is allowed as an exception to the rule.`,
           },
+          ignore: {
+            type: 'array',
+            items: { type: 'string' },
+            uniqueItems: true,
+            default: DEFAULT_OPTIONS.ignore,
+            description: `Input or output properties for which duplicate presence is allowed as an exception to the rule.`,
+          },
         },
         additionalProperties: false,
       },
@@ -44,7 +59,7 @@ export default createESLintRule<Options, MessageIds>({
     },
   },
   defaultOptions: [DEFAULT_OPTIONS],
-  create(context, [{ allowTwoWayDataBinding }]) {
+  create(context, [{ allowTwoWayDataBinding, ignore }]) {
     const parserServices = getTemplateParserServices(context);
 
     return {
@@ -68,7 +83,15 @@ export default createESLintRule<Options, MessageIds>({
           ...duplicateOutputs,
         ] as const;
 
-        allDuplicates.forEach((duplicate) => {
+        const filteredDuplicates =
+          ignore && ignore.length > 0
+            ? allDuplicates.filter(
+                (duplicate) =>
+                  !ignore.includes(getOriginalAttributeName(duplicate)),
+              )
+            : allDuplicates;
+
+        filteredDuplicates.forEach((duplicate) => {
           const loc = parserServices.convertNodeSourceSpanToLoc(
             duplicate.sourceSpan,
           );

packages/eslint-plugin-template/tests/rules/no-duplicate-attributes/cases.ts

@@ -496,4 +496,44 @@ export const invalid = [
       },
     ],
   }),
+  convertAnnotatedSourceToFailureCase({
+    description: 'should not report ignored properties',
+    annotatedSource: `
+        <input [name]="foo" class="css-static" name="bar" [class]="dynamic">
+               ~~~~~~~~~~~~                    ^^^^^^^^^^
+      `,
+    options: [{ ignore: ['class'] }],
+    messages: [
+      {
+        char: '~',
+        messageId,
+        data: { attributeName: 'name' },
+        suggestions: [
+          {
+            messageId: suggestRemoveAttribute,
+            output: `
+        <input class="css-static" name="bar" [class]="dynamic">
+
+      `,
+            data: { attributeName: 'name' },
+          },
+        ],
+      },
+      {
+        char: '^',
+        messageId,
+        data: { attributeName: 'name' },
+        suggestions: [
+          {
+            messageId: suggestRemoveAttribute,
+            output: `
+        <input [name]="foo" class="css-static" [class]="dynamic">
+
+      `,
+            data: { attributeName: 'name' },
+          },
+        ],
+      },
+    ],
+  }),
 ];