no-useless-undefined: Ignore ref(undefined) in Vue project (#1828)

Author: fisker

rules/no-useless-undefined.js

@@ -70,6 +70,8 @@ const shouldIgnore = node => {
 	}
 
 	return compareFunctionNames.has(name)
+		// https://vuejs.org/api/reactivity-core.html#ref
+		|| name === 'ref'
 		// `set.add(undefined)`
 		|| name === 'add'
 		// `map.set(foo, undefined)`

test/no-useless-undefined.mjs

@@ -1,5 +1,5 @@
 import outdent from 'outdent';
-import {getTester} from './utils/test.mjs';
+import {getTester, parsers} from './utils/test.mjs';
 
 const {test} = getTester(import.meta);
 
@@ -436,3 +436,36 @@ test.snapshot({
 		'foo.notBind(bar, undefined)',
 	],
 });
+
+test.snapshot({
+	testerOptions: {
+		parser: parsers.vue,
+	},
+	valid: [
+		outdent`
+			<script>
+			import {ref} from 'vue';
+
+			export default {
+				setup() {
+					return {foo: ref(undefined)};
+				}
+			};
+			</script>
+		`,
+		outdent`
+			<script setup>
+			import * as vue from 'vue';
+			const foo = vue.ref(undefined);
+			</script>
+		`,
+	],
+	invalid: [
+		outdent`
+			<script>
+			import {nextTick} from 'vue';
+			const foo = nextTick(undefined);
+			</script>
+		`,
+	],
+});

test/snapshots/no-useless-undefined.mjs.md

@@ -299,3 +299,28 @@ Generated by [AVA](https://avajs.dev).
     > 1 | foo.notBind(bar, undefined)␊
         |                  ^^^^^^^^^ Do not use useless \`undefined\`.␊
     `
+
+## Invalid #1
+      1 | <script>
+      2 | import {nextTick} from 'vue';
+      3 | const foo = nextTick(undefined);
+      4 | </script>
+
+> Output
+
+    `␊
+      1 | <script>␊
+      2 | import {nextTick} from 'vue';␊
+      3 | const foo = nextTick();␊
+      4 | </script>␊
+    `
+
+> Error 1/1
+
+    `␊
+      1 | <script>␊
+      2 | import {nextTick} from 'vue';␊
+    > 3 | const foo = nextTick(undefined);␊
+        |                      ^^^^^^^^^ Do not use useless \`undefined\`.␊
+      4 | </script>␊
+    `