Add vue/valid-next-tick rule (#1404)

* Add rule docs

* Add rule to collections

* Add rule tests

* Add more test cases

* Add rule implementation

* Fix docs

* Update docs

* Remove categories

* Prevent false positives for `foo.then(nextTick)`

* Suggest `await` instead of fixing it

* Add tests and logic for more false positives

docs/rules/README.md

@@ -325,6 +325,7 @@ For example:
 | [vue/v-for-delimiter-style](./v-for-delimiter-style.md) | enforce `v-for` directive's delimiter style | :wrench: |
 | [vue/v-on-event-hyphenation](./v-on-event-hyphenation.md) | enforce v-on event naming style on custom components in template | :wrench: |
 | [vue/v-on-function-call](./v-on-function-call.md) | enforce or forbid parentheses after method calls without arguments in `v-on` directives | :wrench: |
+| [vue/valid-next-tick](./valid-next-tick.md) | enforce valid `nextTick` function calls | :wrench: |
 
 ### Extension Rules
 

docs/rules/valid-next-tick.md

@@ -0,0 +1,88 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/valid-next-tick
+description: enforce valid `nextTick` function calls
+---
+# vue/valid-next-tick
+
+> enforce valid `nextTick` function calls
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
+- :wrench: The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
+
+## :book: Rule Details
+
+Calling `Vue.nextTick` or `vm.$nextTick` without passing a callback and without awaiting the returned Promise is likely a mistake (probably a missing `await`).
+
+<eslint-code-block fix :rules="{'vue/valid-next-tick': ['error']}">
+
+```vue
+<script>
+import { nextTick as nt } from 'vue';
+
+export default {
+  async mounted() {
+    /* ✗ BAD: no callback function or awaited Promise */
+    nt();
+    Vue.nextTick();
+    this.$nextTick();
+
+    /* ✗ BAD: too many parameters */
+    nt(callback, anotherCallback);
+    Vue.nextTick(callback, anotherCallback);
+    this.$nextTick(callback, anotherCallback);
+
+    /* ✗ BAD: no function call */
+    nt.then(callback);
+    Vue.nextTick.then(callback);
+    this.$nextTick.then(callback);
+    await nt;
+    await Vue.nextTick;
+    await this.$nextTick;
+
+    /* ✗ BAD: both callback function and awaited Promise */
+    nt(callback).then(anotherCallback);
+    Vue.nextTick(callback).then(anotherCallback);
+    this.$nextTick(callback).then(anotherCallback);
+    await nt(callback);
+    await Vue.nextTick(callback);
+    await this.$nextTick(callback);
+
+    /* ✓ GOOD */
+    await nt();
+    await Vue.nextTick();
+    await this.$nextTick();
+
+    /* ✓ GOOD */
+    nt().then(callback);
+    Vue.nextTick().then(callback);
+    this.$nextTick().then(callback);
+
+    /* ✓ GOOD */
+    nt(callback);
+    Vue.nextTick(callback);
+    this.$nextTick(callback);
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :books: Further Reading
+
+- [`Vue.nextTick` API in Vue 2](https://vuejs.org/v2/api/#Vue-nextTick)
+- [`vm.$nextTick` API in Vue 2](https://vuejs.org/v2/api/#vm-nextTick)
+- [Global API Treeshaking](https://v3.vuejs.org/guide/migration/global-api-treeshaking.html)
+- [Global `nextTick` API in Vue 3](https://v3.vuejs.org/api/global-api.html#nexttick)
+- [Instance `$nextTick` API in Vue 3](https://v3.vuejs.org/api/instance-methods.html#nexttick)
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/valid-next-tick.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/valid-next-tick.js)

lib/index.js

@@ -164,6 +164,7 @@ module.exports = {
     'v-on-function-call': require('./rules/v-on-function-call'),
     'v-on-style': require('./rules/v-on-style'),
     'v-slot-style': require('./rules/v-slot-style'),
+    'valid-next-tick': require('./rules/valid-next-tick'),
     'valid-template-root': require('./rules/valid-template-root'),
     'valid-v-bind-sync': require('./rules/valid-v-bind-sync'),
     'valid-v-bind': require('./rules/valid-v-bind'),

lib/rules/valid-next-tick.js

@@ -0,0 +1,204 @@
+/**
+ * @fileoverview enforce valid `nextTick` function calls
+ * @author Flo Edelmann
+ * @copyright 2021 Flo Edelmann. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+const { findVariable } = require('eslint-utils')
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * @param {Identifier} identifier
+ * @param {RuleContext} context
+ * @returns {ASTNode|undefined}
+ */
+function getVueNextTickNode(identifier, context) {
+  // Instance API: this.$nextTick()
+  if (
+    identifier.name === '$nextTick' &&
+    identifier.parent.type === 'MemberExpression' &&
+    utils.isThis(identifier.parent.object, context)
+  ) {
+    return identifier.parent
+  }
+
+  // Vue 2 Global API: Vue.nextTick()
+  if (
+    identifier.name === 'nextTick' &&
+    identifier.parent.type === 'MemberExpression' &&
+    identifier.parent.object.type === 'Identifier' &&
+    identifier.parent.object.name === 'Vue'
+  ) {
+    return identifier.parent
+  }
+
+  // Vue 3 Global API: import { nextTick as nt } from 'vue'; nt()
+  const variable = findVariable(context.getScope(), identifier)
+
+  if (variable != null && variable.defs.length === 1) {
+    const def = variable.defs[0]
+    if (
+      def.type === 'ImportBinding' &&
+      def.node.type === 'ImportSpecifier' &&
+      def.node.imported.type === 'Identifier' &&
+      def.node.imported.name === 'nextTick' &&
+      def.node.parent.type === 'ImportDeclaration' &&
+      def.node.parent.source.value === 'vue'
+    ) {
+      return identifier
+    }
+  }
+
+  return undefined
+}
+
+/**
+ * @param {CallExpression} callExpression
+ * @returns {boolean}
+ */
+function isAwaitedPromise(callExpression) {
+  if (callExpression.parent.type === 'AwaitExpression') {
+    // cases like `await nextTick()`
+    return true
+  }
+
+  if (callExpression.parent.type === 'ReturnStatement') {
+    // cases like `return nextTick()`
+    return true
+  }
+
+  if (
+    callExpression.parent.type === 'MemberExpression' &&
+    callExpression.parent.property.type === 'Identifier' &&
+    callExpression.parent.property.name === 'then'
+  ) {
+    // cases like `nextTick().then()`
+    return true
+  }
+
+  if (
+    callExpression.parent.type === 'VariableDeclarator' ||
+    callExpression.parent.type === 'AssignmentExpression'
+  ) {
+    // cases like `let foo = nextTick()` or `foo = nextTick()`
+    return true
+  }
+
+  if (
+    callExpression.parent.type === 'ArrayExpression' &&
+    callExpression.parent.parent.type === 'CallExpression' &&
+    callExpression.parent.parent.callee.type === 'MemberExpression' &&
+    callExpression.parent.parent.callee.object.type === 'Identifier' &&
+    callExpression.parent.parent.callee.object.name === 'Promise' &&
+    callExpression.parent.parent.callee.property.type === 'Identifier'
+  ) {
+    // cases like `Promise.all([nextTick()])`
+    return true
+  }
+
+  return false
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'enforce valid `nextTick` function calls',
+      // categories: ['vue3-essential', 'essential'],
+      categories: undefined,
+      url: 'https://eslint.vuejs.org/rules/valid-next-tick.html'
+    },
+    fixable: 'code',
+    schema: []
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    return utils.defineVueVisitor(context, {
+      /** @param {Identifier} node */
+      Identifier(node) {
+        const nextTickNode = getVueNextTickNode(node, context)
+        if (!nextTickNode || !nextTickNode.parent) {
+          return
+        }
+
+        const parentNode = nextTickNode.parent
+
+        if (
+          parentNode.type === 'CallExpression' &&
+          parentNode.callee !== nextTickNode
+        ) {
+          // cases like `foo.then(nextTick)` are allowed
+          return
+        }
+
+        if (
+          parentNode.type === 'VariableDeclarator' ||
+          parentNode.type === 'AssignmentExpression'
+        ) {
+          // cases like `let foo = nextTick` or `foo = nextTick` are allowed
+          return
+        }
+
+        if (parentNode.type !== 'CallExpression') {
+          context.report({
+            node,
+            message: '`nextTick` is a function.',
+            fix(fixer) {
+              return fixer.insertTextAfter(node, '()')
+            }
+          })
+          return
+        }
+
+        if (parentNode.arguments.length === 0) {
+          if (!isAwaitedPromise(parentNode)) {
+            context.report({
+              node,
+              message:
+                'Await the Promise returned by `nextTick` or pass a callback function.',
+              suggest: [
+                {
+                  desc: 'Add missing `await` statement.',
+                  fix(fixer) {
+                    return fixer.insertTextBefore(parentNode, 'await ')
+                  }
+                }
+              ]
+            })
+          }
+          return
+        }
+
+        if (parentNode.arguments.length > 1) {
+          context.report({
+            node,
+            message: '`nextTick` expects zero or one parameters.'
+          })
+          return
+        }
+
+        if (isAwaitedPromise(parentNode)) {
+          context.report({
+            node,
+            message:
+              'Either await the Promise or pass a callback function to `nextTick`.'
+          })
+        }
+      }
+    })
+  }
+}