import/extensions setting: parser whitelist. fixes #267

Author: benmosher

Diff for: CHANGELOG.md

@@ -14,6 +14,10 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - [`extensions`]: fallback to source path for extension enforcement if imported
   module is not resolved. Also, never report for builtins (i.e. `path`). ([#296])
 
+### Breaking
+- [`import/extensions` setting]: a whitelist of file extensions to parse as modules
+  and search for `export`s. Defaults to `['.js']`.
+
 ## resolvers/webpack/0.2.4 - 2016-04-29
 ### Changed
 - automatically find webpack config with `interpret`-able extensions ([#287], thanks [@taion])
@@ -180,6 +184,7 @@ for info on changes for earlier releases.
 
 [`import/cache` setting]: ./README.md#importcache
 [`import/ignore` setting]: ./README.md#importignore
+[`import/extensions` setting]: ./README.md#importextensions
 
 [`no-unresolved`]: ./docs/rules/no-unresolved.md
 [`no-deprecated`]: ./docs/rules/no-deprecated.md

Diff for: README.md

@@ -147,6 +147,19 @@ If you are interesting in writing a resolver, see the [spec](./resolvers/README.
 
 You may set the following settings in your `.eslintrc`:
 
+#### `import/extensions`
+
+A whitelist of file extensions that will be parsed as modules and inspected for
+`export`s. This defaults to `['.js']`, unless you are using the `react` shared config,
+in which case it is specified as `['.js', '.jsx']`.
+
+Note that this is different from (and likely a subset of) any `import/resolver`
+extensions settings, which may include `.json`, `.coffee`, etc. which will still
+factor into the `no-unresolved` rule.
+
+Also, `import/ignore` patterns will overrule this whitelist, so `node_modules` that
+end in `.js` will still be ignored by default.
+
 #### `import/ignore`
 
 A list of regex strings that, if matched by a path, will

Diff for: config/react.js

@@ -0,0 +1,8 @@
+/**
+ * - adds `.jsx` as an extension
+ */
+module.exports = {
+  settings: {
+    'import/extensions': ['.js', '.jsx'],
+  },
+}

Diff for: src/core/ignore.js

@@ -1,9 +1,28 @@
+import { extname } from 'path'
+import Set from 'es6-set'
+
+// one-shot memoized
+let cachedSet, lastSettings
+function validExtensions({ settings }) {
+  if (cachedSet && settings === lastSettings) {
+    return cachedSet
+  }
+
+  // todo: add 'mjs'?
+  lastSettings = settings
+  cachedSet = new Set(settings['import/extensions'] || [ '.js' ])
+  return cachedSet
+}
+
 export default function ignore(path, context) {
   // ignore node_modules by default
-  var ignoreStrings = context.settings['import/ignore']
+  const ignoreStrings = context.settings['import/ignore']
     ? [].concat(context.settings['import/ignore'])
     : ['node_modules']
 
+  // check extension whitelist first (cheap)
+  if (!validExtensions(context).has(extname(path))) return true
+
   if (ignoreStrings.length === 0) return false
 
   for (var i = 0; i < ignoreStrings.length; i++) {

Diff for: src/index.js

@@ -28,6 +28,9 @@ export const configs = {
   'errors': require('../config/errors'),
   'warnings': require('../config/warnings'),
 
+  // useful stuff for folks using React
+  'react': require('../config/react'),
+
   // shhhh... work in progress "secret" rules
   'stage-0': require('../config/stage-0'),
 }

Diff for: tests/files/data.json

@@ -0,0 +1 @@
+{ "foo": "bar" }

Diff for: tests/src/rules/named.js

@@ -1,4 +1,4 @@
-import { test } from '../utils'
+import { test, SYNTAX_CASES } from '../utils'
 import { RuleTester } from 'eslint'
 
 var ruleTester = new RuleTester()
@@ -96,6 +96,7 @@ ruleTester.run('named', rule, {
       settings: { 'import/ignore': ['common'] },
     }),
 
+    ...SYNTAX_CASES,
   ],
 
   invalid: [
@@ -166,6 +167,7 @@ ruleTester.run('named', rule, {
     // parse errors
     test({
       code: "import { a } from './test.coffee';",
+      settings: { 'import/extensions': ['.js', '.coffee'] },
       errors: [{
         message: "Parse errors in imported module './test.coffee': Unexpected token > (1:20)",
         type: 'Literal',

Diff for: tests/src/rules/namespace.js

@@ -1,4 +1,4 @@
-var test = require('../utils').test
+import { test, SYNTAX_CASES } from '../utils'
 import { RuleTester } from 'eslint'
 
 var ruleTester = new RuleTester({ env: { es6: true }})
@@ -86,6 +86,7 @@ const valid = [
     parser: 'babel-eslint',
   }),
 
+  ...SYNTAX_CASES,
 ]
 
 const invalid = [

Diff for: tests/src/rules/no-named-as-default.js

@@ -1,4 +1,4 @@
-import { test } from '../utils'
+import { test, SYNTAX_CASES } from '../utils'
 import { RuleTester } from 'eslint'
 
 const ruleTester = new RuleTester()
@@ -16,6 +16,8 @@ ruleTester.run('no-named-as-default', rule, {
          , parser: 'babel-eslint' }),
     test({ code: 'export bar from "./bar";'
          , parser: 'babel-eslint' }),
+
+    ...SYNTAX_CASES,
   ],
 
   invalid: [

Diff for: tests/src/utils.js

@@ -57,4 +57,7 @@ export const SYNTAX_CASES = [
   test({ code: 'export default x' }),
   test({ code: 'export default class x {}' }),
 
+  // issue #267: parser whitelist
+  test({ code: 'import json from "./data.json"' }),
+
  ]