[Fix] extensions: Ignore root external modules when checking for ex…

…tensions

src/core/importType.js

@@ -84,6 +84,10 @@ function typeTest(name, settings, path) {
   return 'unknown'
 }
 
+export function isScopedModule(name) {
+  return name.indexOf('@') === 0
+}
+
 export default function resolveImportType(name, context) {
   return typeTest(name, context.settings, resolve(name, context))
 }

src/rules/extensions.js

@@ -1,7 +1,7 @@
 import path from 'path'
 
 import resolve from 'eslint-module-utils/resolve'
-import { isBuiltIn, isExternalModule, isScoped } from '../core/importType'
+import { isBuiltIn, isExternalModule, isScoped, isScopedModule } from '../core/importType'
 import docsUrl from '../docsUrl'
 
 const enumValues = { enum: [ 'always', 'ignorePackages', 'never' ] }
@@ -126,6 +126,14 @@ module.exports = {
       return resolvedFileWithoutExtension === resolve(file, context)
     }
 
+    function isExternalRootModule(file) {
+      const slashCount = file.split('/').length - 1
+
+      if (isScopedModule(file) && slashCount <= 1) return true
+      if (isExternalModule(file, context, resolve(file, context)) && !slashCount) return true
+      return false
+    }
+
     function checkFileExtension(node) {
       const { source } = node
 
@@ -139,6 +147,10 @@ module.exports = {
 
       const importPath = importPathWithQueryString.replace(/\?(.*)$/, '')
 
+      // don't enforce in root external packages as they may have names with `.js`.
+      // Like `import Decimal from decimal.js`)
+      if (isExternalRootModule(importPath)) return
+
       const resolvedPath = resolve(importPath, context)
 
       // get extension from resolved path, if possible.

tests/src/rules/extensions.js

@@ -117,6 +117,16 @@ ruleTester.run('extensions', rule, {
       options: [ 'never' ],
     }),
 
+    // Root packages should be ignored and they are names not files
+    test({
+      code: [
+        'import lib from "pkg.js"',
+        'import lib2 from "pgk/package"',
+        'import lib3 from "@name/pkg.js"',
+      ].join('\n'),
+      options: [ 'never' ],
+    }),
+
     // Query strings.
     test({
       code: 'import bare from "./foo?a=True.ext"',
@@ -126,6 +136,15 @@ ruleTester.run('extensions', rule, {
       code: 'import bare from "./foo.js?a=True"',
       options: [ 'always' ],
     }),
+
+    test({
+      code: [
+        'import lib from "pkg"',
+        'import lib2 from "pgk/package.js"',
+        'import lib3 from "@name/pkg"',
+      ].join('\n'),
+      options: [ 'always' ],
+    }),
   ],
 
   invalid: [
@@ -137,15 +156,6 @@ ruleTester.run('extensions', rule, {
         column: 15,
       } ],
     }),
-    test({
-      code: 'import a from "a"',
-      options: [ 'always' ],
-      errors: [ {
-        message: 'Missing file extension "js" for "a"',
-        line: 1,
-        column: 15,
-      } ],
-    }),
     test({
       code: 'import dot from "./file.with.dot"',
       options: [ 'always' ],
@@ -285,11 +295,35 @@ ruleTester.run('extensions', rule, {
       ],
     }),
     test({
-      code: 'import thing from "non-package"',
+      code: 'import thing from "non-package/test"',
       options: [ 'always' ],
       errors: [
         {
-            message: 'Missing file extension for "non-package"',
+            message: 'Missing file extension for "non-package/test"',
+            line: 1,
+            column: 19,
+        },
+      ],
+    }),
+
+    test({
+      code: 'import thing from "@name/pkg/test"',
+      options: [ 'always' ],
+      errors: [
+        {
+            message: 'Missing file extension for "@name/pkg/test"',
+            line: 1,
+            column: 19,
+        },
+      ],
+    }),
+
+    test({
+      code: 'import thing from "@name/pkg/test.js"',
+      options: [ 'never' ],
+      errors: [
+        {
+            message: 'Unexpected use of file extension "js" for "@name/pkg/test.js"',
             line: 1,
             column: 19,
         },