feat(eslint-plugin): [no-empty-interface] noEmptyWithSuper fixer (#1247)

typescript-eslint · Nov 25, 2019 · b91b0ba · b91b0ba
1 parent f5c0e02
commit b91b0ba
Show file tree

Hide file tree

Showing 3 changed files with 76 additions and 1 deletion.
diff --git a/packages/eslint-plugin/README.md b/packages/eslint-plugin/README.md
@@ -162,7 +162,7 @@ Then you should add `airbnb` (or `airbnb-base`) to your `extends` section of `.e
 | [`@typescript-eslint/no-array-constructor`](./docs/rules/no-array-constructor.md)                         | Disallow generic `Array` constructors                                                                                                               | :heavy_check_mark: | :wrench: |                   |
 | [`@typescript-eslint/no-dynamic-delete`](./docs/rules/no-dynamic-delete.md)                               | Bans usage of the delete operator with computed key expressions                                                                                     |                    | :wrench: |                   |
 | [`@typescript-eslint/no-empty-function`](./docs/rules/no-empty-function.md)                               | Disallow empty functions                                                                                                                            | :heavy_check_mark: |          |                   |
-| [`@typescript-eslint/no-empty-interface`](./docs/rules/no-empty-interface.md)                             | Disallow the declaration of empty interfaces                                                                                                        | :heavy_check_mark: |          |                   |
+| [`@typescript-eslint/no-empty-interface`](./docs/rules/no-empty-interface.md)                             | Disallow the declaration of empty interfaces                                                                                                        | :heavy_check_mark: | :wrench: |
 | [`@typescript-eslint/no-explicit-any`](./docs/rules/no-explicit-any.md)                                   | Disallow usage of the `any` type                                                                                                                    | :heavy_check_mark: | :wrench: |                   |
 | [`@typescript-eslint/no-extra-non-null-assertion`](./docs/rules/no-extra-non-null-assertion.md)                           | Disallow extra non-null assertion                                                                                                            |                    |          |                   |
 | [`@typescript-eslint/no-extra-parens`](./docs/rules/no-extra-parens.md)                                   | Disallow unnecessary parentheses                                                                                                                    |                    | :wrench: |                   |

diff --git a/packages/eslint-plugin/src/rules/no-empty-interface.ts b/packages/eslint-plugin/src/rules/no-empty-interface.ts
@@ -16,6 +16,7 @@ export default util.createRule<Options, MessageIds>({
       category: 'Best Practices',
       recommended: 'error',
     },
+    fixable: 'code',
     messages: {
       noEmpty: 'An empty interface is equivalent to `{}`.',
       noEmptyWithSuper:
@@ -41,6 +42,8 @@ export default util.createRule<Options, MessageIds>({
   create(context, [{ allowSingleExtends }]) {
     return {
       TSInterfaceDeclaration(node): void {
+        const sourceCode = context.getSourceCode();
+
         if (node.body.body.length !== 0) {
           // interface contains members --> Nothing to report
           return;
@@ -59,6 +62,20 @@ export default util.createRule<Options, MessageIds>({
             context.report({
               node: node.id,
               messageId: 'noEmptyWithSuper',
+              fix(fixer) {
+                if (node.extends && node.extends.length) {
+                  return [
+                    fixer.replaceText(
+                      node,
+                      `type ${sourceCode.getText(
+                        node.id,
+                      )} = ${sourceCode.getText(node.extends[0])}`,
+                    ),
+                  ];
+                }
+
+                return null;
+              },
             });
           }
         }

diff --git a/packages/eslint-plugin/tests/rules/no-empty-interface.test.ts b/packages/eslint-plugin/tests/rules/no-empty-interface.test.ts
@@ -73,5 +73,63 @@ interface Bar extends Foo {}
         },
       ],
     },
+    {
+      code: 'interface Foo extends Array<number> {}',
+      output: 'type Foo = Array<number>',
+      errors: [
+        {
+          messageId: 'noEmptyWithSuper',
+          line: 1,
+          column: 11,
+        },
+      ],
+    },
+    {
+      code: 'interface Foo extends Array<number | {}> { }',
+      output: 'type Foo = Array<number | {}>',
+      errors: [
+        {
+          messageId: 'noEmptyWithSuper',
+          line: 1,
+          column: 11,
+        },
+      ],
+    },
+    {
+      code: `
+interface Bar {
+  bar: string;
+}
+interface Foo extends Array<Bar> {}
+`,
+      output: `
+interface Bar {
+  bar: string;
+}
+type Foo = Array<Bar>
+`,
+      errors: [
+        {
+          messageId: 'noEmptyWithSuper',
+          line: 5,
+          column: 11,
+        },
+      ],
+    },
+    {
+      code: `
+type R = Record<string, unknown>;
+interface Foo extends R {   };`,
+      output: `
+type R = Record<string, unknown>;
+type Foo = R;`,
+      errors: [
+        {
+          messageId: 'noEmptyWithSuper',
+          line: 3,
+          column: 11,
+        },
+      ],
+    },
   ],
 });