Add vue/require-expose rule (#1568)

Author: ota-meshi

Diff for: docs/rules/README.md

@@ -325,6 +325,7 @@ For example:
 | [vue/padding-line-between-blocks](./padding-line-between-blocks.md) | require or disallow padding lines between blocks | :wrench: |
 | [vue/require-direct-export](./require-direct-export.md) | require the component to be directly exported |  |
 | [vue/require-emit-validator](./require-emit-validator.md) | require type definitions in emits |  |
+| [vue/require-expose](./require-expose.md) | require declare public properties using `expose` |  |
 | [vue/require-name-property](./require-name-property.md) | require a name property in Vue components |  |
 | [vue/script-indent](./script-indent.md) | enforce consistent indentation in `<script>` | :wrench: |
 | [vue/sort-keys](./sort-keys.md) | enforce sort-keys in a manner that is compatible with order-in-components |  |

Diff for: docs/rules/require-expose.md

@@ -0,0 +1,120 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/require-expose
+description: require declare public properties using `expose`
+---
+# vue/require-expose
+
+> require declare public properties using `expose`
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+
+## :book: Rule Details
+
+This rule enforces the component to explicitly declare the exposed properties to the component using `expose`. You can use `expose` to control the internal properties of a component so that they cannot be referenced externally.
+
+The `expose` API was officially introduced in Vue 3.2.
+
+<eslint-code-block :rules="{'vue/require-expose': ['error']}">
+
+```vue
+<script>
+/* ✓ GOOD */
+export default {
+  expose: ['increment'],
+  data() {
+    return { count: 0 }
+  },
+  methods: {
+    increment() {
+      this.count++
+    }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/require-expose': ['error']}">
+
+```vue
+<script>
+/* ✗ BAD */
+export default {
+  data() {
+    return { count: 0 }
+  },
+  methods: {
+    increment() {
+      this.count++
+    }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/require-expose': ['error']}">
+
+```vue
+<script>
+/* ✓ GOOD */
+import { ref } from 'vue'
+
+export default {
+  setup(props, { expose }) {
+    const count = ref(0)
+
+    function increment() {
+      count.value++
+    }
+    // public
+    expose({
+      increment
+    })
+    // private
+    return { count }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+<eslint-code-block :rules="{'vue/require-expose': ['error']}">
+
+```vue
+<script>
+/* ✗ BAD */
+import { ref } from 'vue'
+
+export default {
+  setup(props) {
+    const count = ref(0)
+
+    function increment() {
+      count.value++
+    }
+    return { increment, count }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :books: Further Reading
+
+- [Vue RFCs - 0042-expose-api](https://github.com/vuejs/rfcs/blob/master/active-rfcs/0042-expose-api.md)
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/require-expose.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/require-expose.js)

Diff for: lib/index.js

@@ -145,6 +145,7 @@ module.exports = {
     'require-direct-export': require('./rules/require-direct-export'),
     'require-emit-validator': require('./rules/require-emit-validator'),
     'require-explicit-emits': require('./rules/require-explicit-emits'),
+    'require-expose': require('./rules/require-expose'),
     'require-name-property': require('./rules/require-name-property'),
     'require-prop-type-constructor': require('./rules/require-prop-type-constructor'),
     'require-prop-types': require('./rules/require-prop-types'),

Diff for: lib/rules/require-explicit-emits.js

@@ -18,7 +18,12 @@
 // Requirements
 // ------------------------------------------------------------------------------
 
-const { findVariable } = require('eslint-utils')
+const {
+  findVariable,
+  isOpeningBraceToken,
+  isClosingBraceToken,
+  isOpeningBracketToken
+} = require('eslint-utils')
 const utils = require('../utils')
 const { capitalize } = require('../utils/casing')
 
@@ -53,34 +58,6 @@ const FIX_EMITS_AFTER_OPTIONS = [
   'renderTriggered',
   'errorCaptured'
 ]
-
-/**
- * Check whether the given token is a left brace.
- * @param {Token} token The token to check.
- * @returns {boolean} `true` if the token is a left brace.
- */
-function isLeftBrace(token) {
-  return token != null && token.type === 'Punctuator' && token.value === '{'
-}
-
-/**
- * Check whether the given token is a right brace.
- * @param {Token} token The token to check.
- * @returns {boolean} `true` if the token is a right brace.
- */
-function isRightBrace(token) {
-  return token != null && token.type === 'Punctuator' && token.value === '}'
-}
-
-/**
- * Check whether the given token is a left bracket.
- * @param {Token} token The token to check.
- * @returns {boolean} `true` if the token is a left bracket.
- */
-function isLeftBracket(token) {
-  return token != null && token.type === 'Punctuator' && token.value === '['
-}
-
 // ------------------------------------------------------------------------------
 // Rule Definition
 // ------------------------------------------------------------------------------
@@ -486,7 +463,7 @@ function buildSuggest(define, emits, nameNode, context) {
     const emitsOptionValue = emitsOption.value
     if (emitsOptionValue.type === 'ArrayExpression') {
       const leftBracket = /** @type {Token} */ (
-        sourceCode.getFirstToken(emitsOptionValue, isLeftBracket)
+        sourceCode.getFirstToken(emitsOptionValue, isOpeningBracketToken)
       )
       return [
         {
@@ -504,7 +481,7 @@ function buildSuggest(define, emits, nameNode, context) {
       ]
     } else if (emitsOptionValue.type === 'ObjectExpression') {
       const leftBrace = /** @type {Token} */ (
-        sourceCode.getFirstToken(emitsOptionValue, isLeftBrace)
+        sourceCode.getFirstToken(emitsOptionValue, isOpeningBraceToken)
       )
       return [
         {
@@ -548,10 +525,10 @@ function buildSuggest(define, emits, nameNode, context) {
           )
         } else {
           const objectLeftBrace = /** @type {Token} */ (
-            sourceCode.getFirstToken(object, isLeftBrace)
+            sourceCode.getFirstToken(object, isOpeningBraceToken)
           )
           const objectRightBrace = /** @type {Token} */ (
-            sourceCode.getLastToken(object, isRightBrace)
+            sourceCode.getLastToken(object, isClosingBraceToken)
           )
           return fixer.insertTextAfter(
             objectLeftBrace,
@@ -583,10 +560,10 @@ function buildSuggest(define, emits, nameNode, context) {
           )
         } else {
           const objectLeftBrace = /** @type {Token} */ (
-            sourceCode.getFirstToken(object, isLeftBrace)
+            sourceCode.getFirstToken(object, isOpeningBraceToken)
           )
           const objectRightBrace = /** @type {Token} */ (
-            sourceCode.getLastToken(object, isRightBrace)
+            sourceCode.getLastToken(object, isClosingBraceToken)
           )
           return fixer.insertTextAfter(
             objectLeftBrace,