feat(eslint-plugin): [no-extran-class] add allowWithDecorator opt

packages/eslint-plugin/src/rules/no-extraneous-class.ts

@@ -9,6 +9,7 @@ type Options = [
     allowConstructorOnly?: boolean;
     allowEmpty?: boolean;
     allowStaticOnly?: boolean;
+    allowWithDecorator?: boolean;
   },
 ];
 type MessageIds = 'empty' | 'onlyStatic' | 'onlyConstructor';
@@ -36,6 +37,9 @@ export default util.createRule<Options, MessageIds>({
           allowStaticOnly: {
             type: 'boolean',
           },
+          allowWithDecorator: {
+            type: 'boolean',
+          },
         },
       },
     ],
@@ -50,9 +54,24 @@ export default util.createRule<Options, MessageIds>({
       allowConstructorOnly: false,
       allowEmpty: false,
       allowStaticOnly: false,
+      allowWithDecorator: false,
     },
   ],
-  create(context, [{ allowConstructorOnly, allowEmpty, allowStaticOnly }]) {
+  create(
+    context,
+    [{ allowConstructorOnly, allowEmpty, allowStaticOnly, allowWithDecorator }],
+  ) {
+    const isAllowWithDecorator = (
+      node: TSESTree.ClassDeclaration | TSESTree.ClassExpression | undefined,
+    ): boolean => {
+      return !!(
+        allowWithDecorator &&
+        node &&
+        node.decorators &&
+        node.decorators.length
+      );
+    };
+
     return {
       ClassBody(node): void {
         const parent = node.parent as
@@ -65,9 +84,8 @@ export default util.createRule<Options, MessageIds>({
         }
 
         const reportNode = 'id' in parent && parent.id ? parent.id : parent;
-
         if (node.body.length === 0) {
-          if (allowEmpty) {
+          if (allowEmpty || isAllowWithDecorator(parent)) {
             return;
           }
 

packages/eslint-plugin/tests/rules/no-extraneous-class.test.ts

@@ -65,6 +65,13 @@ export class Bar {
     },
     // https://github.com/typescript-eslint/typescript-eslint/issues/170
     'export default class { hello() { return "I am foo!"; } }',
+    {
+      code: `
+@FooDecorator
+class Foo {}
+      `,
+      options: [{ allowWithDecorator: true }],
+    },
   ],
 
   invalid: [
@@ -125,5 +132,17 @@ export class AClass {
         },
       ],
     },
+    {
+      code: `
+@FooDecorator
+class Foo {}
+      `,
+      options: [{ allowWithDecorator: false }],
+      errors: [
+        {
+          messageId: 'empty',
+        },
+      ],
+    },
   ],
 });