feat(eslint-plugin): [no-empty-function] new allow option overrideMet…

…hods (#4923)
typescript-eslint · May 16, 2022 · 13c05ae · 13c05ae
1 parent 04a216c
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diff --git a/packages/eslint-plugin/docs/rules/no-empty-function.md b/packages/eslint-plugin/docs/rules/no-empty-function.md
@@ -28,7 +28,8 @@ This rule adds the following options:
 type AdditionalAllowOptionEntries =
   | 'private-constructors'
   | 'protected-constructors'
-  | 'decoratedFunctions';
+  | 'decoratedFunctions'
+  | 'overrideMethods';
 
 type AllowOptionEntries =
   | BaseNoEmptyFunctionAllowOptionEntries
@@ -77,6 +78,22 @@ class Foo {
 }
 ```
 
+### allow: `overrideMethods`
+
+Examples of correct code for the `{ "allow": ["overrideMethods"] }` option:
+
+```ts
+abstract class Base {
+  protected greet(): void {
+    console.log('Hello!');
+  }
+}
+
+class Foo extends Base {
+  protected override greet(): void {}
+}
+```
+
 ## How to Use
 
 ```jsonc

diff --git a/packages/eslint-plugin/src/rules/no-empty-function.ts b/packages/eslint-plugin/src/rules/no-empty-function.ts
@@ -30,6 +30,7 @@ const schema = util.deepMerge(
             'asyncFunctions',
             'asyncMethods',
             'decoratedFunctions',
+            'overrideMethods',
           ],
         },
       },
@@ -63,6 +64,7 @@ export default util.createRule<Options, MessageIds>({
     );
     const isAllowedPrivateConstructors = allow.includes('private-constructors');
     const isAllowedDecoratedFunctions = allow.includes('decoratedFunctions');
+    const isAllowedOverrideMethods = allow.includes('overrideMethods');
 
     /**
      * Check if the method body is empty
@@ -138,12 +140,24 @@ export default util.createRule<Options, MessageIds>({
       return false;
     }
 
+    function isAllowedEmptyOverrideMethod(
+      node: TSESTree.FunctionExpression,
+    ): boolean {
+      return (
+        isAllowedOverrideMethods &&
+        isBodyEmpty(node) &&
+        node.parent?.type === AST_NODE_TYPES.MethodDefinition &&
+        node.parent.override === true
+      );
+    }
+
     return {
       ...rules,
       FunctionExpression(node): void {
         if (
           isAllowedEmptyConstructor(node) ||
-          isAllowedEmptyDecoratedFunctions(node)
+          isAllowedEmptyDecoratedFunctions(node) ||
+          isAllowedEmptyOverrideMethod(node)
         ) {
           return;
         }

diff --git a/packages/eslint-plugin/tests/rules/no-empty-function.test.ts b/packages/eslint-plugin/tests/rules/no-empty-function.test.ts
@@ -72,6 +72,14 @@ class Foo {
       `,
       options: [{ allow: ['decoratedFunctions'] }],
     },
+    {
+      code: `
+class Foo extends Base {
+  override foo() {}
+}
+      `,
+      options: [{ allow: ['overrideMethods'] }],
+    },
   ],
 
   invalid: [
@@ -192,5 +200,22 @@ class Foo {
         },
       ],
     },
+    {
+      code: `
+class Foo extends Base {
+  override foo() {}
+}
+      `,
+      errors: [
+        {
+          messageId: 'unexpected',
+          data: {
+            name: "method 'foo'",
+          },
+          line: 3,
+          column: 18,
+        },
+      ],
+    },
   ],
 });