Add sfc-locale-attr rule

docs/rules/README.md

@@ -36,3 +36,4 @@
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [@intlify/vue-i18n/<wbr>prefer-linked-key-with-paren](./prefer-linked-key-with-paren.html) | enforce linked key to be enclosed in parentheses | :black_nib: |
+| [@intlify/vue-i18n/<wbr>sfc-locale-attr](./sfc-locale-attr.html) | require or disallow the locale attribute on `<i18n>` block |  |

docs/rules/sfc-locale-attr.md

@@ -0,0 +1,89 @@
+---
+title: '@intlify/vue-i18n/sfc-locale-attr'
+description: require or disallow the locale attribute on `<i18n>` block
+---
+
+# @intlify/vue-i18n/sfc-locale-attr
+
+> require or disallow the locale attribute on `<i18n>` block
+
+## :book: Rule Details
+
+This rule aims to enforce the `<i18n>` block to use or not the `locale` attribute.
+
+<eslint-code-block>
+
+<!-- eslint-skip -->
+
+```vue
+<script>
+/* eslint @intlify/vue-i18n/sfc-locale-attr: "error" */
+</script>
+
+<!-- ✓ GOOD -->
+<i18n locale="en">
+{
+  "message": "hello!"
+}
+</i18n>
+
+<!-- ✗ BAD -->
+<i18n>
+{
+  "en": {
+    "message": "hello!"
+  }
+}
+</i18n>
+```
+
+</eslint-code-block>
+
+## :gear: Options
+
+```json
+{
+  "@intlify/vue-i18n/sfc-locale-attr": [
+    "error",
+    "always" //"always" or "never"
+  ]
+}
+```
+
+- `"always"` ... The `<i18n>` blocks requires the locale attribute.
+- `"never"` ... Do not use the locale attribute on `<i18n>` blocks.
+
+### Examples of code for this rule with `"never"` option:
+
+<eslint-code-block>
+
+<!-- eslint-skip -->
+
+```vue
+<script>
+/* eslint @intlify/vue-i18n/sfc-locale-attr: ["error", "never"] */
+</script>
+
+<!-- ✓ GOOD -->
+<i18n>
+{
+  "en": {
+    "message": "hello!"
+  }
+}
+</i18n>
+
+<!-- ✗ BAD -->
+<i18n locale="en">
+{
+  "message": "hello!"
+}
+</i18n>
+```
+
+</eslint-code-block>
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/intlify/eslint-plugin-vue-i18n/blob/master/lib/rules/sfc-locale-attr.ts)
+- [Test source](https://github.com/intlify/eslint-plugin-vue-i18n/tree/master/tests/lib/rules/sfc-locale-attr.ts)

lib/rules.ts

@@ -14,6 +14,7 @@ import noUnusedKeys from './rules/no-unused-keys'
 import noVHtml from './rules/no-v-html'
 import preferLinkedKeyWithParen from './rules/prefer-linked-key-with-paren'
 import preferSfcLangAttr from './rules/prefer-sfc-lang-attr'
+import sfcLocaleAttr from './rules/sfc-locale-attr'
 import validMessageSyntax from './rules/valid-message-syntax'
 
 export = {
@@ -32,5 +33,6 @@ export = {
   'no-v-html': noVHtml,
   'prefer-linked-key-with-paren': preferLinkedKeyWithParen,
   'prefer-sfc-lang-attr': preferSfcLangAttr,
+  'sfc-locale-attr': sfcLocaleAttr,
   'valid-message-syntax': validMessageSyntax
 }

lib/rules/sfc-locale-attr.ts

@@ -0,0 +1,67 @@
+import type { RuleContext, RuleListener } from '../types'
+import { isI18nBlock, getAttribute } from '../utils/index'
+import { createRule } from '../utils/rule'
+
+export = createRule({
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'require or disallow the locale attribute on `<i18n>` block',
+      category: 'Stylistic Issues',
+      url: 'https://eslint-plugin-vue-i18n.intlify.dev/rules/sfc-locale-attr.html',
+      recommended: false
+    },
+    fixable: null,
+    schema: [
+      {
+        enum: ['always', 'never']
+      }
+    ],
+    messages: {
+      required: '`locale` attribute is required.',
+      disallowed: '`locale` attribute is disallowed.'
+    }
+  },
+  create(context: RuleContext): RuleListener {
+    const df = context.parserServices.getDocumentFragment?.()
+    if (!df) {
+      return {}
+    }
+    const always = context.options[0] !== 'never'
+    return {
+      Program() {
+        for (const i18n of df.children.filter(isI18nBlock)) {
+          const srcAttrs = getAttribute(i18n, 'src')
+          if (srcAttrs != null) {
+            continue
+          }
+          const localeAttrs = getAttribute(i18n, 'locale')
+
+          if (
+            localeAttrs != null &&
+            localeAttrs.value != null &&
+            localeAttrs.value.value
+          ) {
+            if (always) {
+              continue
+            }
+            // disallowed
+            context.report({
+              loc: localeAttrs.loc,
+              messageId: 'disallowed'
+            })
+          } else {
+            if (!always) {
+              continue
+            }
+            // missing
+            context.report({
+              loc: i18n.startTag.loc,
+              messageId: 'required'
+            })
+          }
+        }
+      }
+    }
+  }
+})

lib/utils.ts

@@ -15,6 +15,7 @@ import * as localeMessages from './utils/locale-messages'
 import * as parsers from './utils/parsers'
 import * as pathUtils from './utils/path-utils'
 import * as resourceLoader from './utils/resource-loader'
+import * as rule from './utils/rule'
 
 export = {
   'cache-function': cacheFunction,
@@ -32,5 +33,6 @@ export = {
   'locale-messages': localeMessages,
   parsers,
   'path-utils': pathUtils,
-  'resource-loader': resourceLoader
+  'resource-loader': resourceLoader,
+  rule
 }

package.json

@@ -107,10 +107,11 @@
     "coverage": "nyc report --reporter lcov && opener coverage/lcov-report/index.html",
     "docs": "npm run build && vuepress dev docs",
     "docs:build": "npm run build && vuepress build docs",
-    "generate": "ts-node scripts/update.ts && prettier . --write",
+    "generate": "ts-node scripts/update.ts && npm run format",
     "lint": "eslint . --ext js,ts,vue,md --ignore-pattern \"/tests/fixtures\"",
     "lint-fix": "eslint . --ext js,ts,vue,md --ignore-pattern \"/tests/fixtures\" --fix",
     "lint:docs": "prettier docs --check",
+    "format": "prettier . --write",
     "release:prepare": "shipjs prepare",
     "release:trigger": "shipjs trigger",
     "test": "mocha --require ts-node/register \"./tests/**/*.ts\"",

scripts/new-rule.ts

@@ -93,7 +93,6 @@ description: description
 
 > description
 
-## :book: Rule Details
 ## :book: Rule Details
 
 This rule reports ???.

tests/lib/rules/sfc-locale-attr.ts

@@ -0,0 +1,111 @@
+import { RuleTester } from 'eslint'
+import rule = require('../../../lib/rules/sfc-locale-attr')
+const vueParser = require.resolve('vue-eslint-parser')
+
+const tester = new RuleTester({
+  parser: vueParser,
+  parserOptions: {
+    ecmaVersion: 2020,
+    sourceType: 'module'
+  }
+})
+
+tester.run('sfc-locale-attr', rule as never, {
+  valid: [
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n locale="en">
+      {
+        "message": "hello!"
+      }
+      </i18n>
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n locale="en">
+      {
+        "message": "hello!"
+      }
+      </i18n>
+      `,
+      options: ['always']
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n>
+      {
+        "en": {
+          "message": "hello!"
+        }
+      }
+      </i18n>
+      `,
+      options: ['never']
+    }
+  ],
+  invalid: [
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n>
+      {
+        "en": {
+          "message": "hello!"
+        }
+      }
+      </i18n>
+      `,
+      errors: [
+        {
+          message: '`locale` attribute is required.',
+          line: 2,
+          column: 7
+        }
+      ]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n>
+      {
+        "en": {
+          "message": "hello!"
+        }
+      }
+      </i18n>
+      `,
+      options: ['always'],
+      errors: [
+        {
+          message: '`locale` attribute is required.',
+          line: 2,
+          column: 7
+        }
+      ]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <i18n locale="en">
+      {
+        "en": {
+          "message": "hello!"
+        }
+      }
+      </i18n>
+      `,
+      options: ['never'],
+      errors: [
+        {
+          message: '`locale` attribute is disallowed.',
+          line: 2,
+          column: 13
+        }
+      ]
+    }
+  ]
+})