⭐️New: Add vue/camelcase rule

Author: ota-meshi

Diff for: docs/rules/README.md

@@ -140,6 +140,7 @@ For example:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [vue/array-bracket-spacing](./array-bracket-spacing.md) | enforce consistent spacing inside array brackets | :wrench: |
+| [vue/camelcase](./camelcase.md) | enforce camelcase naming convention |  |
 | [vue/component-name-in-template-casing](./component-name-in-template-casing.md) | enforce specific casing for the component naming style in template | :wrench: |
 | [vue/eqeqeq](./eqeqeq.md) | require the use of `===` and `!==` | :wrench: |
 | [vue/key-spacing](./key-spacing.md) | enforce consistent spacing between keys and values in object literal properties | :wrench: |

Diff for: docs/rules/camelcase.md

@@ -0,0 +1,21 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/camelcase
+description: enforce camelcase naming convention
+---
+# vue/camelcase
+> enforce camelcase naming convention
+
+This rule is the same rule as core [camelcase] rule but it applies to the expressions in `<template>`.
+
+## :books: Further reading
+
+- [camelcase]
+
+[camelcase]: https://eslint.org/docs/rules/camelcase
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/camelcase.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/camelcase.js)

Diff for: lib/index.js

@@ -10,6 +10,7 @@ module.exports = {
     'array-bracket-spacing': require('./rules/array-bracket-spacing'),
     'attribute-hyphenation': require('./rules/attribute-hyphenation'),
     'attributes-order': require('./rules/attributes-order'),
+    'camelcase': require('./rules/camelcase'),
     'comment-directive': require('./rules/comment-directive'),
     'component-name-in-template-casing': require('./rules/component-name-in-template-casing'),
     'eqeqeq': require('./rules/eqeqeq'),

Diff for: lib/rules/camelcase.js

@@ -0,0 +1,9 @@
+/**
+ * @author Yosuke Ota
+ */
+'use strict'
+
+const { wrapCoreRule } = require('../utils')
+
+// eslint-disable-next-line
+module.exports = wrapCoreRule(require('eslint/lib/rules/camelcase'))

Diff for: tests/lib/rules/camelcase.js

@@ -0,0 +1,34 @@
+/**
+ * @author Yosuke Ota
+ */
+'use strict'
+
+const RuleTester = require('eslint').RuleTester
+const rule = require('../../../lib/rules/camelcase')
+
+const tester = new RuleTester({
+  parser: 'vue-eslint-parser',
+  parserOptions: { ecmaVersion: 2015 }
+})
+
+tester.run('camelcase', rule, {
+  valid: [
+    `<template>
+      <div :attr="{ myPref: 1 }" />
+    </template>`
+  ],
+  invalid: [
+    {
+      code: `
+        <template>
+          <div :attr="{ my_pref: 1 }" />
+        </template>`,
+      errors: [
+        {
+          message: 'Identifier \'my_pref\' is not in camel case.',
+          line: 3
+        }
+      ]
+    }
+  ]
+})