extension whitelist feature

README.md

@@ -200,6 +200,28 @@ You may use `env` as an alias for `envs` (just don't specify both).
 If you're using your custom linter globally (you installed it with `-g`), then you also need to
 install `babel-eslint` globally with `npm install babel-eslint -g`.
 
+### Extension whitelist
+
+`standard-engine` can be set up to look for whitelisted
+[ESLint shareable config](http://eslint.org/docs/developer-guide/shareable-configs)s
+to extend the rules from.
+
+For example, an `opts` object may include:
+
+```js
+{
+  whitelist: ['pocketlint-node', 'pocketlint-ava']
+}
+```
+
+Then, if any of the packages `eslint-config-pocketlint-node`/`eslint-config-pocketlint-ava`
+are found to be installed, the rules will extend from them, as well.
+
+This feature allows users of this package to curate a set of official extensions.
+
+Intentionally, this is not read from `package.json`. If it were, it would not have been
+a whitelist feature.
+
 ## API Usage
 
 ### `standardEngine.lintText(text, [opts], callback)`
@@ -215,6 +237,7 @@ be provided:
   globals: [],  // custom global variables to declare
   plugins: [],  // custom eslint plugins
   envs: [],     // custom eslint environment
+  whitelist: []// shareable configs to extend from if installed
   parser: ''    // custom js parser (e.g. babel-eslint)
 }
 ```
@@ -253,6 +276,7 @@ Lint the provided `files` globs. An `opts` object may be provided:
   globals: [],  // custom global variables to declare
   plugins: [],  // custom eslint plugins
   envs: [],     // custom eslint environment
+  whitelist: []// shareable configs to extend from if installed
   parser: ''    // custom js parser (e.g. babel-eslint)
 }
 ```
@@ -276,6 +300,7 @@ This is the full set of options accepted by the above APIs. Not all options make
   globals: [],  // custom global variables to declare
   plugins: [],  // custom eslint plugins
   envs: [],     // custom eslint environment
+  whitelist: []// shareable configs to extend from if installed
   parser: ''    // custom js parser (e.g. babel-eslint)
 }
 ```

index.js

@@ -41,6 +41,24 @@ function Linter (opts) {
     plugins: [],
     useEslintrc: false
   }, opts.eslintConfig)
+
+  if (opts.whitelist) {
+    let original = self.eslintConfig.extends
+    let ekstends = original
+    ekstends = typeof ekstends === 'string' ? [ekstends] : ekstends || []
+    opts.whitelist.forEach((shareable) => {
+      let installed = true
+      try {
+        require('eslint-config-' + shareable)
+      } catch (e) {
+        installed = false
+      }
+      if (installed) {
+        ekstends.push(shareable)
+      }
+    })
+    self.eslintConfig.extends = ekstends.length ? ekstends : original
+  }
 }
 
 /**

package.json

@@ -16,6 +16,7 @@
   },
   "devDependencies": {
     "babel-eslint": "^7.1.1",
+    "clone": "^2.1.0",
     "cross-spawn": "^5.0.0",
     "eslint": "^3.0.1",
     "eslint-config-standard": "^6.0.0-beta.0",
@@ -24,6 +25,8 @@
     "eslint-plugin-react": "^6.0.0",
     "eslint-plugin-standard": "^2.0.0",
     "mkdirp": "^0.5.0",
+    "mock-require": "^2.0.0",
+    "require-uncached": "^1.0.3",
     "run-parallel-limit": "^1.0.1",
     "standard": "*",
     "standard-packages": "^3.0.14",

test/api.js

@@ -1,12 +1,19 @@
 var eslint = require('eslint')
-var Linter = require('../').linter
 var test = require('tape')
+const mock = require('mock-require')
+const requireUncached = require('require-uncached')
+const clone = require('clone')
+
+const defaultOpts = {
+  eslint,
+  eslintConfig: require('../tmp/standard/options').eslintConfig
+}
+
+const getLinter = () => requireUncached('../').linter
 
 function getStandard () {
-  return new Linter({
-    eslint: eslint,
-    eslintConfig: require('../tmp/standard/options').eslintConfig
-  })
+  const Linter = getLinter()
+  return new Linter(defaultOpts)
 }
 
 test('api: lintFiles', function (t) {
@@ -44,3 +51,63 @@ test('api: parseOpts -- avoid self.eslintConfig global mutation', function (t) {
   t.deepEqual(opts.globals, ['what'])
   t.deepEqual(standard.eslintConfig.globals, [])
 })
+
+const defaultWhitelist = ['foo', 'bar']
+const defaultWhitelistPkgs = ['eslint-config-foo', 'eslint-config-bar']
+
+test('api: whitelist -- provided whitelist, no existing extends', function (t) {
+  t.plan(1)
+  const opts = clone(defaultOpts)
+  opts.whitelist = clone(defaultWhitelist)
+  defaultWhitelistPkgs.forEach(name => mock(name, {}))
+  const Linter = getLinter()
+  let linter = new Linter(opts)
+  t.deepEqual(linter.eslintConfig.extends, defaultWhitelist)
+  defaultWhitelistPkgs.forEach(name => mock.stop(name))
+})
+
+test('api: whitelist -- provided whitelist, string existing extends', function (t) {
+  t.plan(1)
+  const opts = clone(defaultOpts)
+  opts.whitelist = clone(defaultWhitelist)
+  opts.eslintConfig.extends = 'baz'
+  defaultWhitelistPkgs.forEach(name => mock(name, {}))
+  const Linter = getLinter()
+  let linter = new Linter(opts)
+  const expected = ['baz'].concat(defaultWhitelist)
+  t.deepEqual(linter.eslintConfig.extends, expected)
+  defaultWhitelistPkgs.forEach(name => mock.stop(name))
+})
+
+test('api: whitelist -- provided whitelist, multiple existing extends', function (t) {
+  t.plan(1)
+  const opts = clone(defaultOpts)
+  opts.whitelist = clone(defaultWhitelist)
+  opts.eslintConfig.extends = ['baz', 'yad']
+  defaultWhitelistPkgs.forEach(name => mock(name, {}))
+  const Linter = getLinter()
+  let linter = new Linter(opts)
+  const expected = ['baz', 'yad'].concat(defaultWhitelist)
+  t.deepEqual(linter.eslintConfig.extends, expected)
+  defaultWhitelistPkgs.forEach(name => mock.stop(name))
+})
+
+test('api: whitelist -- packages not installed', function (t) {
+  t.plan(1)
+  const opts = clone(defaultOpts)
+  opts.whitelist = clone(defaultWhitelist)
+  const Linter = getLinter()
+  let linter = new Linter(opts)
+  t.equals(linter.eslintConfig.extends, undefined)
+})
+
+test('api: whitelist -- some packages installed', function (t) {
+  t.plan(1)
+  const opts = clone(defaultOpts)
+  opts.whitelist = clone(defaultWhitelist)
+  const Linter = getLinter()
+  mock(defaultWhitelistPkgs[0], {})
+  let linter = new Linter(opts)
+  t.deepEqual(linter.eslintConfig.extends, defaultWhitelist.slice(0, 1))
+  mock.stop(defaultWhitelistPkgs[0])
+})