Add flow config and rules

flow.js

@@ -0,0 +1,10 @@
+module.exports = {
+  extends: [
+    'plugin:flowtype/recommended',
+    'wyze/rules/flow',
+  ],
+  parser: 'babel-eslint',
+  plugins: [
+    'flowtype',
+  ],
+}

package.json

@@ -29,17 +29,21 @@
     }
   },
   "peerDependencies": {
+    "babel-eslint": "^7.1.0",
     "eslint": "^3.9.0",
     "eslint-config-airbnb": "^12.0.0",
+    "eslint-plugin-flowtype": "^2.25.0",
     "eslint-plugin-import": "^2.0.0",
     "eslint-plugin-jsx-a11y": "^2.2.0",
     "eslint-plugin-react": "^6.4.0",
     "eslint-plugin-wyze": "^2.0.0"
   },
   "devDependencies": {
     "ava": "^0.16.0",
+    "babel-eslint": "^7.1.0",
     "eslint": "^3.9.1",
     "eslint-config-airbnb": "^12.0.0",
+    "eslint-plugin-flowtype": "^2.25.0",
     "eslint-plugin-import": "^2.0.1",
     "eslint-plugin-jsx-a11y": "^2.2.3",
     "eslint-plugin-react": "^6.4.1",

readme.md

@@ -21,6 +21,12 @@ Project without React:
 $ npm i --save-dev eslint eslint-config-airbnb eslint-config-wyze eslint-plugin-import eslint-plugin-wyze
 ```
 
+Project with Flow:
+
+```sh
+$ npm i --save-dev babel-eslint eslint eslint-config-wyze eslint-plugin-flowtype
+```
+
 ## Usage
 
 ### package.json

rules/flow.js

@@ -0,0 +1,31 @@
+module.exports = {
+  rules: {
+    // same as comma-dangle from ESLint
+    // https://github.com/gajus/eslint-plugin-flowtype#delimiter-dangle
+    'flowtype/delimiter-dangle': [ 2, 'always-multiline' ],
+    // disallow duplicate keys in types
+    // https://github.com/gajus/eslint-plugin-flowtype#no-dupe-keys
+    'flowtype/no-dupe-keys': 2,
+    // better to be specific, but only warn
+    // https://github.com/gajus/eslint-plugin-flowtype#no-weak-types
+    'flowtype/no-weak-types': 1,
+    // only use commas in object types
+    // https://github.com/gajus/eslint-plugin-flowtype#object-type-delimiter
+    'flowtype/object-type-delimiter': [ 2, 'comma' ],
+    // type all the functions!
+    // https://github.com/gajus/eslint-plugin-flowtype#require-parameter-type
+    'flowtype/require-parameter-type': 2,
+    // just warn about missing return types
+    // https://github.com/gajus/eslint-plugin-flowtype#require-return-type
+    'flowtype/require-return-type': 1,
+    // warn when a file isn't typed
+    // https://github.com/gajus/eslint-plugin-flowtype#require-valid-file-annotation
+    'flowtype/require-valid-file-annotation': 1,
+    // ew, semicolons
+    // https://github.com/gajus/eslint-plugin-flowtype#semi
+    'flowtype/semi': [ 2, 'never' ],
+    // enforce type names to begin with uppercase letter
+    // https://github.com/gajus/eslint-plugin-flowtype#type-id-match
+    'flowtype/type-id-match': [ 2, '^[A-Z].*$' ],
+  },
+}

test/flow.js

@@ -0,0 +1,25 @@
+import flow from '../flow'
+import test from 'ava'
+
+test('extends files', t => {
+  const expected = [
+    'plugin:flowtype/recommended',
+    'wyze/rules/flow',
+  ]
+
+  t.deepEqual(flow.extends, expected, 'extending incorrect rules')
+})
+
+test('parser is set correctly', t => {
+  const expected = 'babel-eslint'
+
+  t.is(flow.parser, expected)
+})
+
+test('plugins are set correctly', t => {
+  const expected = [
+    'flowtype',
+  ]
+
+  t.deepEqual(flow.plugins, expected)
+})

test/rules/flow.js

@@ -0,0 +1,8 @@
+import { rules } from '../../rules/flow'
+import test from 'ava'
+
+test('only flowtype rules', t => {
+  Object.keys(rules).forEach(rule => {
+    t.truthy(~rule.indexOf('flowtype/'))
+  })
+})