[Fix] no-cycle/extensions: fix isExternalModule usage

CHANGELOG.md

@@ -15,6 +15,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - [`no-unused-modules`]: make type imports mark a module as used (fixes #1924) ([#1974], thanks [@cherryblossom000])
 - [`no-cycle`]: fix perf regression ([#1944], thanks [@Blasz])
 - [`first`]: fix handling of `import = require` ([#1963], thanks [@MatthiasKunnen])
+- [`no-cycle`]/[`extensions`]: fix isExternalModule usage ([#1696], thanks [@paztis])
 
 ### Changed
 - [Generic Import Callback] Make callback for all imports once in rules ([#1237], thanks [@ljqx])
@@ -788,6 +789,7 @@ for info on changes for earlier releases.
 [#1719]: https://github.com/benmosher/eslint-plugin-import/pull/1719
 [#1704]: https://github.com/benmosher/eslint-plugin-import/issues/1704
 [#1702]: https://github.com/benmosher/eslint-plugin-import/issues/1702
+[#1696]: https://github.com/benmosher/eslint-plugin-import/pull/1696
 [#1691]: https://github.com/benmosher/eslint-plugin-import/pull/1691
 [#1690]: https://github.com/benmosher/eslint-plugin-import/pull/1690
 [#1689]: https://github.com/benmosher/eslint-plugin-import/pull/1689
@@ -1310,3 +1312,4 @@ for info on changes for earlier releases.
 [@swernerx]: https://github.com/swernerx
 [@fsmaia]: https://github.com/fsmaia
 [@MatthiasKunnen]: https://github.com/MatthiasKunnen
+[@paztis]: https://github.com/paztis

src/core/importType.js

@@ -41,8 +41,11 @@ function isSubpath(subpath, path) {
         (right >= normPath.length || normPath[right] === '/');
 }
 
-const externalModuleRegExp = /^\w/;
+const externalModuleRegExp = /^(?:\w|@)/;
 export function isExternalModule(name, settings, path) {
+  if (arguments.length < 3) {
+    throw new TypeError('isExternalModule: name, settings, and path are all required');
+  }
   return externalModuleRegExp.test(name) && isExternalPath(path, name, settings);
 }
 

src/rules/extensions.js

@@ -157,8 +157,11 @@ module.exports = {
       const extension = path.extname(resolvedPath || importPath).substring(1);
 
       // determine if this is a module
-      const isPackage = isExternalModule(importPath, context.settings)
-        || isScoped(importPath);
+      const isPackage = isExternalModule(
+        importPath,
+        context.settings,
+        resolve(importPath, context)
+      ) || isScoped(importPath);
 
       if (!extension || !importPath.endsWith(`.${extension}`)) {
         const extensionRequired = isUseOfExtensionRequired(extension, isPackage);

src/rules/no-cycle.js

@@ -3,6 +3,7 @@
  * @author Ben Mosher
  */
 
+import resolve from 'eslint-module-utils/resolve';
 import Exports from '../ExportMap';
 import { isExternalModule } from '../core/importType';
 import moduleVisitor, { makeOptionsSchema } from 'eslint-module-utils/moduleVisitor';
@@ -41,7 +42,11 @@ module.exports = {
 
     const options = context.options[0] || {};
     const maxDepth = typeof options.maxDepth === 'number' ? options.maxDepth : Infinity;
-    const ignoreModule = (name) => options.ignoreExternal ? isExternalModule(name) : false;
+    const ignoreModule = (name) => options.ignoreExternal && isExternalModule(
+      name,
+      context.settings,
+      resolve(name, context)
+    );
 
     function checkSourceValue(sourceNode, importer) {
       if (ignoreModule(sourceNode.value)) {

tests/src/rules/extensions.js

@@ -547,5 +547,34 @@ ruleTester.run('extensions', rule, {
         },
       ],
     }),
+    test({
+      code: 'import foo from "@/ImNotAScopedModule.js"',
+      options: ['never'],
+      errors: [
+        {
+          message: 'Unexpected use of file extension "js" for "@/ImNotAScopedModule.js"',
+          line: 1,
+        },
+      ],
+    }),
+    test({
+      code: `
+        import _ from 'lodash';
+        import m from '@test-scope/some-module/index.js';
+
+        import bar from './bar';
+      `,
+      options: ['never'],
+      settings: {
+        'import/resolver': 'webpack',
+        'import/external-module-folders': ['node_modules', 'symlinked-module'],
+      },
+      errors: [
+        {
+          message: 'Unexpected use of file extension "js" for "@test-scope/some-module/index.js"',
+          line: 3,
+        },
+      ],
+    }),
   ],
 });

tests/src/rules/no-cycle.js

@@ -45,15 +45,15 @@ ruleTester.run('no-cycle', rule, {
       options: [{ ignoreExternal: true }],
       settings: {
         'import/resolver': 'webpack',
-        'import/external-module-folders': ['external'],
+        'import/external-module-folders': ['cycles/external'],
       },
     }),
     test({
       code: 'import { foo } from "./external-depth-two"',
       options: [{ ignoreExternal: true }],
       settings: {
         'import/resolver': 'webpack',
-        'import/external-module-folders': ['external'],
+        'import/external-module-folders': ['cycles/external'],
       },
     }),
     test({
@@ -84,15 +84,15 @@ ruleTester.run('no-cycle', rule, {
       errors: [error(`Dependency cycle detected.`)],
       settings: {
         'import/resolver': 'webpack',
-        'import/external-module-folders': ['external'],
+        'import/external-module-folders': ['cycles/external'],
       },
     }),
     test({
       code: 'import { foo } from "./external-depth-two"',
       errors: [error(`Dependency cycle via cycles/external/depth-one:1`)],
       settings: {
         'import/resolver': 'webpack',
-        'import/external-module-folders': ['external'],
+        'import/external-module-folders': ['cycles/external'],
       },
     }),
     test({