From e349989f6007a2d0ee1ab2ec0ac9702e823a0019 Mon Sep 17 00:00:00 2001
From: sapphi-red <green@sapphi.red>
Date: Sun, 3 Jan 2021 17:30:29 +0900
Subject: [PATCH] Add composition api's computed function support to
 vue/return-in-computed-property refs #1393

---
 docs/rules/return-in-computed-property.md     |  39 +++++-
 lib/rules/return-in-computed-property.js      |  35 ++++-
 .../lib/rules/return-in-computed-property.js  | 122 ++++++++++++++++++
 3 files changed, 191 insertions(+), 5 deletions(-)

diff --git a/docs/rules/return-in-computed-property.md b/docs/rules/return-in-computed-property.md
index d25225798..0ade8e5ae 100644
--- a/docs/rules/return-in-computed-property.md
+++ b/docs/rules/return-in-computed-property.md
@@ -2,18 +2,18 @@
 pageClass: rule-details
 sidebarDepth: 0
 title: vue/return-in-computed-property
-description: enforce that a return statement is present in computed property
+description: enforce that a return statement is present in computed property and function
 since: v3.7.0
 ---
 # vue/return-in-computed-property
 
-> enforce that a return statement is present in computed property
+> enforce that a return statement is present in computed property and function
 
 - :gear: This rule is included in all of `"plugin:vue/vue3-essential"`, `"plugin:vue/essential"`, `"plugin:vue/vue3-strongly-recommended"`, `"plugin:vue/strongly-recommended"`, `"plugin:vue/vue3-recommended"` and `"plugin:vue/recommended"`.
 
 ## :book: Rule Details
 
-This rule enforces that a `return` statement is present in `computed` properties.
+This rule enforces that a `return` statement is present in `computed` properties and functions.
 
 <eslint-code-block :rules="{'vue/return-in-computed-property': ['error']}">
 
@@ -46,6 +46,39 @@ export default {
 
 </eslint-code-block>
 
+<eslint-code-block :rules="{'vue/return-in-computed-property': ['error']}">
+
+```vue
+<script>
+import {computed} from 'vue'
+export default {
+  setup() {
+    const foobar = useFoobar()
+
+    /* ✓ GOOD */
+    const foo = computed(() => {
+      if (foobar.bar) {
+        return foobar.baz
+      } else {
+        return foobar.baf
+      }
+    })
+    const bar = computed(() => false)
+
+    /* ✗ BAD */
+    const baz = computed(() => {
+      if (foobar.baf) {
+        return foobar.baf
+      }
+    })
+    const baf = computed(() => {})
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
 ## :wrench: Options
 
 ```json
diff --git a/lib/rules/return-in-computed-property.js b/lib/rules/return-in-computed-property.js
index 770e0c597..9908fe4fe 100644
--- a/lib/rules/return-in-computed-property.js
+++ b/lib/rules/return-in-computed-property.js
@@ -3,7 +3,7 @@
  * @author Armano
  */
 'use strict'
-
+const { ReferenceTracker } = require('eslint-utils')
 const utils = require('../utils')
 
 /**
@@ -47,13 +47,36 @@ module.exports = {
      * @type {Set<ComponentComputedProperty>}
      */
     const computedProperties = new Set()
+    /** @type {(FunctionExpression | ArrowFunctionExpression)[]} */
+    const computedFunctionNodes = []
 
     // ----------------------------------------------------------------------
     // Public
     // ----------------------------------------------------------------------
 
     return Object.assign(
-      {},
+      {
+        Program() {
+          const tracker = new ReferenceTracker(context.getScope())
+          const traceMap = utils.createCompositionApiTraceMap({
+            [ReferenceTracker.ESM]: true,
+            computed: {
+              [ReferenceTracker.CALL]: true
+            }
+          })
+
+          for (const { node } of tracker.iterateEsmReferences(traceMap)) {
+            if (node.type !== 'CallExpression') {
+              continue
+            }
+
+            const getter = utils.getGetterBodyFromComputedFunction(node)
+            if (getter) {
+              computedFunctionNodes.push(getter)
+            }
+          }
+        }
+      },
       utils.defineVueVisitor(context, {
         onVueObjectEnter(obj) {
           for (const computedProperty of utils.getComputedProperties(obj)) {
@@ -76,6 +99,14 @@ module.exports = {
               })
             }
           })
+          computedFunctionNodes.forEach((cf) => {
+            if (cf === node) {
+              context.report({
+                node,
+                message: 'Expected to return a value in computed function.'
+              })
+            }
+          })
         }
       )
     )
diff --git a/tests/lib/rules/return-in-computed-property.js b/tests/lib/rules/return-in-computed-property.js
index a7c14a51f..df6b1b680 100644
--- a/tests/lib/rules/return-in-computed-property.js
+++ b/tests/lib/rules/return-in-computed-property.js
@@ -104,6 +104,56 @@ ruleTester.run('return-in-computed-property', rule, {
       `,
       parserOptions,
       options: [{ treatUndefinedAsUnspecified: false }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        import {computed} from 'vue'
+        export default {
+          setup() {
+            const foo = computed(() => true)
+            const bar = computed(function() {
+              return false
+            })
+            const bar3 = computed({
+              set: () => true,
+              get: () => true
+            })
+            const bar4 = computed(() => {
+              if (foo) {
+                return true
+              } else {
+                return false
+              }
+            })
+            const foo2 = computed(() => {
+              const options = []
+              this.matches.forEach((match) => {
+                options.push(match)
+              })
+              return options
+            })
+          }
+        }
+      `,
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        import {computed} from 'vue'
+        export default {
+          setup() {
+            const foo = computed({
+              get: () => {
+                return
+              }
+            })
+          }
+        }
+      `,
+      parserOptions,
+      options: [{ treatUndefinedAsUnspecified: false }]
     }
   ],
 
@@ -272,6 +322,78 @@ ruleTester.run('return-in-computed-property', rule, {
           line: 5
         }
       ]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        import {computed} from 'vue'
+        export default {
+          setup() {
+            const foo = computed(() => {})
+            const foo2 = computed(function() {})
+            const foo3 = computed(() => {
+              if (a) {
+                return
+              }
+            })
+            const foo4 = computed({
+              set: () => {},
+              get: () => {}
+            })
+            const foo5 = computed(() => {
+              const bar = () => {
+                return this.baz * 2
+              }
+              bar()
+            })
+          }
+        }
+      `,
+      parserOptions,
+      errors: [
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 5
+        },
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 6
+        },
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 7
+        },
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 14
+        },
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 16
+        }
+      ]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        import {computed} from 'vue'
+        export default {
+          setup() {
+            const foo = computed(() => {})
+            const baz = computed(() => {
+              return
+            })
+          }
+        }
+      `,
+      parserOptions,
+      options: [{ treatUndefinedAsUnspecified: false }],
+      errors: [
+        {
+          message: 'Expected to return a value in computed function.',
+          line: 5
+        }
+      ]
     }
   ]
 })