Add vue/require-emit-validator rule

docs/rules/README.md

@@ -132,6 +132,7 @@ Enforce all the rules in this category, as well as all higher priority rules, wi
 | [vue/one-component-per-file](./one-component-per-file.md) | enforce that each component should be in its own file |  |
 | [vue/prop-name-casing](./prop-name-casing.md) | enforce specific casing for the Prop name in Vue components |  |
 | [vue/require-default-prop](./require-default-prop.md) | require default value for props |  |
+| [vue/require-emit-types](./require-emit-types.md) | require type definitions in emits |  |
 | [vue/require-explicit-emits](./require-explicit-emits.md) | require `emits` option with name triggered by `$emit()` |  |
 | [vue/require-prop-types](./require-prop-types.md) | require type definitions in props |  |
 | [vue/singleline-html-element-content-newline](./singleline-html-element-content-newline.md) | require a line break before and after the contents of a singleline element | :wrench: |

docs/rules/require-emit-types.md

@@ -0,0 +1,61 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/require-emit-types
+description: require type definitions in emits
+---
+# vue/require-emit-types
+
+> require type definitions in emits
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+- :gear: This rule is included in `"plugin:vue/vue3-strongly-recommended"` and `"plugin:vue/vue3-recommended"`.
+
+## :book: Rule Details
+
+This rule enforces that a `emits` statement contains type definition.
+
+Declaring `emits` with types can bring better maintenance.
+Even if using with TypeScript, this can provide better type inference when annotating parameters with types.
+
+<eslint-code-block :rules="{'vue/require-emit-types': ['error']}">
+
+```vue
+<script>
+/* ✓ GOOD */
+Vue.component('foo', {
+  emits: {
+    // Emit with arguments
+    foo: (payload) => { /* validate payload */ },
+    // Emit without parameters
+    bar: () => true,
+  }
+})
+
+/* ✗ BAD */
+Vue.component('bar', {
+  emits: ['foo']
+})
+
+Vue.component('baz', {
+  emits: {
+    foo: null,
+  }
+})
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :books: Further Reading
+
+- [API Reference](https://v3.vuejs.org/api/options-data.html#emits)
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/require-emit-types.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/require-emit-types.js)

lib/configs/vue3-strongly-recommended.js

@@ -23,6 +23,7 @@ module.exports = {
     'vue/one-component-per-file': 'warn',
     'vue/prop-name-casing': 'warn',
     'vue/require-default-prop': 'warn',
+    'vue/require-emit-types': 'warn',
     'vue/require-explicit-emits': 'warn',
     'vue/require-prop-types': 'warn',
     'vue/singleline-html-element-content-newline': 'warn',

lib/index.js

@@ -140,6 +140,7 @@ module.exports = {
     'require-component-is': require('./rules/require-component-is'),
     'require-default-prop': require('./rules/require-default-prop'),
     'require-direct-export': require('./rules/require-direct-export'),
+    'require-emit-types': require('./rules/require-emit-types'),
     'require-explicit-emits': require('./rules/require-explicit-emits'),
     'require-name-property': require('./rules/require-name-property'),
     'require-prop-type-constructor': require('./rules/require-prop-type-constructor'),

lib/rules/require-emit-types.js

@@ -0,0 +1,69 @@
+/**
+ * @fileoverview Emit definitions should be detailed
+ * @author Pig Fang
+ */
+'use strict'
+
+const utils = require('../utils')
+
+/**
+ * @typedef {import('../utils').ComponentArrayEmit} ComponentArrayEmit
+ * @typedef {import('../utils').ComponentObjectEmit} ComponentObjectEmit
+ */
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'require type definitions in emits',
+      categories: ['vue3-strongly-recommended'],
+      url: 'https://eslint.vuejs.org/rules/require-emit-types.html'
+    },
+    fixable: null,
+    messages: {
+      missing: 'Emit "{{name}}" should define at least its type.'
+    },
+    schema: []
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    // ----------------------------------------------------------------------
+    // Helpers
+    // ----------------------------------------------------------------------
+
+    /**
+     * @param {ComponentArrayEmit|ComponentObjectEmit} emit
+     */
+    function checker({ value, node, emitName }) {
+      const hasType =
+        !!value &&
+        (value.type === 'ArrowFunctionExpression' ||
+          value.type === 'FunctionExpression')
+
+      if (!hasType) {
+        const name =
+          emitName ||
+          (node.type === 'Identifier' && node.name) ||
+          'Unknown emit'
+
+        context.report({
+          node,
+          messageId: 'missing',
+          data: { name }
+        })
+      }
+    }
+
+    // ----------------------------------------------------------------------
+    // Public
+    // ----------------------------------------------------------------------
+
+    return utils.executeOnVue(context, (obj) => {
+      utils.getComponentEmits(obj).forEach(checker)
+    })
+  }
+}