Merge pull request #1012 from silvenon/extensions-export

Support export declarations in extensions rule

Author: ljharb

src/rules/extensions.js

@@ -122,6 +122,10 @@ module.exports = {
 
     function checkFileExtension(node) {
       const { source } = node
+
+      // bail if the declaration doesn't have a source, e.g. "export { foo };"
+      if (!source) return
+
       const importPath = source.value
 
       // don't enforce anything on builtins
@@ -159,6 +163,7 @@ module.exports = {
 
     return {
       ImportDeclaration: checkFileExtension,
+      ExportNamedDeclaration: checkFileExtension,
     }
   },
 }

tests/src/rules/extensions.js

@@ -100,6 +100,22 @@ ruleTester.run('extensions', rule, {
         },
       },
     }),
+
+    // export (#964)
+    test({
+      code: [
+        'export { foo } from "./foo.js"',
+        'export { bar }',
+      ].join('\n'),
+      options: [ 'always' ],
+    }),
+    test({
+      code: [
+        'export { foo } from "./foo"',
+        'export { bar }',
+      ].join('\n'),
+      options: [ 'never' ],
+    }),
   ],
 
   invalid: [
@@ -314,5 +330,34 @@ ruleTester.run('extensions', rule, {
       options: [ 'never', {ignorePackages: true} ],
     }),
 
+    // export (#964)
+    test({
+      code: [
+        'export { foo } from "./foo"',
+        'export { bar }',
+      ].join('\n'),
+      options: [ 'always' ],
+      errors: [
+        {
+          message: 'Missing file extension for "./foo"',
+          line: 1,
+          column: 21,
+        },
+      ],
+    }),
+    test({
+      code: [
+        'export { foo } from "./foo.js"',
+        'export { bar }',
+      ].join('\n'),
+      options: [ 'never' ],
+      errors: [
+        {
+          message: 'Unexpected use of file extension "js" for "./foo.js"',
+          line: 1,
+          column: 21,
+        },
+      ],
+    }),
   ],
 })