Add no-named-default rule (#596)

* Add empty `no-named-default` rule and tests (failing)

* Functioning `no-named-default` rule with tests

* Document `no-named-default` rule

* Add `no-named-default` to README

* Simplify docs

* Add `no-named-default` note to CHANGELOG

* Remove unnecessary check for `name` key

* Simplify rule logic, add new test, fix syntax error in docs

* Remove source check, use template literal syntax for message

* Simplify rationale in docs

Author: ntdb

CHANGELOG.md

@@ -4,6 +4,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This change log adheres to standards from [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+### Added
+- Add [`no-named-default`] rule: style-guide rule to report use of unnecessarily named default imports
+
 ### Fixed
 - [`prefer-default-export`] handles re-exported default exports ([#609])
 - Fix crash when using `newline-after-import` with decorators ([#592])

README.md

@@ -85,8 +85,9 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 * Enforce a convention in module import order ([`order`])
 * Enforce a newline after import statements ([`newline-after-import`])
 * Prefer a default export if module exports a single name ([`prefer-default-export`])
-* Limit the maximum number of dependencies a module can have. ([`max-dependencies`])
-* Forbid unassigned imports. ([`no-unassigned-import`])
+* Limit the maximum number of dependencies a module can have ([`max-dependencies`])
+* Forbid unassigned imports ([`no-unassigned-import`])
+* Forbid named default exports ([`no-named-default`])
 
 [`first`]: ./docs/rules/first.md
 [`no-duplicates`]: ./docs/rules/no-duplicates.md
@@ -97,6 +98,7 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 [`prefer-default-export`]: ./docs/rules/prefer-default-export.md
 [`max-dependencies`]: ./docs/rules/max-dependencies.md
 [`no-unassigned-import`]: ./docs/rules/no-unassigned-import.md
+[`no-named-default`]: ./docs/rules/no-named-default.md
 
 ## Installation
 

docs/rules/no-named-default.md

@@ -0,0 +1,27 @@
+# no-named-default
+
+Reports use of a default export as a locally named import.
+
+Rationale: the syntax exists to import default exports expressively, let's use it.
+
+## Rule Details
+
+Given:
+```js
+// foo.js
+export default 'foo';
+export const bar = 'baz';
+```
+
+...these would be valid:
+```js
+import foo from './foo.js';
+import foo, { bar } from './foo.js';
+```
+
+...and these would be reported:
+```js
+// message: Using exported name 'bar' as identifier for default export.
+import { default as foo } from './foo.js';
+import { default as foo, bar } from './foo.js';
+```

src/index.js

@@ -10,6 +10,7 @@ export const rules = {
   'no-restricted-paths': require('./rules/no-restricted-paths'),
   'no-internal-modules': require('./rules/no-internal-modules'),
 
+  'no-named-default': require('./rules/no-named-default'),
   'no-named-as-default': require('./rules/no-named-as-default'),
   'no-named-as-default-member': require('./rules/no-named-as-default-member'),
 

src/rules/no-named-default.js

@@ -0,0 +1,19 @@
+module.exports = {
+  meta: {
+    docs: {},
+  },
+
+  create: function (context) {
+    return {
+      'ImportDeclaration': function (node) {
+        node.specifiers.forEach(function (im) {
+          if (im.type === 'ImportSpecifier' && im.imported.name === 'default') {
+            context.report({
+              node: im.local,
+              message: `Use default import syntax to import \'${im.local.name}\'.` })
+          }
+        })
+      },
+    }
+  },
+}

tests/src/rules/no-named-default.js

@@ -0,0 +1,39 @@
+import { test, SYNTAX_CASES } from '../utils'
+import { RuleTester } from 'eslint'
+
+const ruleTester = new RuleTester()
+    , rule = require('rules/no-named-default')
+
+ruleTester.run('no-named-default', rule, {
+  valid: [
+    test({code: 'import bar from "./bar";'}),
+    test({code: 'import bar, { foo } from "./bar";'}),
+
+    ...SYNTAX_CASES,
+  ],
+
+  invalid: [
+    test({
+      code: 'import { default } from "./bar";',
+      errors: [{
+        message: 'Use default import syntax to import \'default\'.',
+        type: 'Identifier',
+      }],
+      parser: 'babel-eslint',
+    }),
+    test({
+      code: 'import { default as bar } from "./bar";',
+      errors: [{
+        message: 'Use default import syntax to import \'bar\'.',
+        type: 'Identifier',
+      }],
+    }),
+    test({
+      code: 'import { foo, default as bar } from "./bar";',
+      errors: [{
+        message: 'Use default import syntax to import \'bar\'.',
+        type: 'Identifier',
+      }],
+    }),
+  ],
+})