add excludedRunes option

Author: baseballyama

packages/eslint-plugin-svelte/src/rule-types.ts

@@ -523,8 +523,8 @@ type SveltePreferClassDirective = []|[{
 }]
 // ----- svelte/prefer-const -----
 type SveltePreferConst = []|[{
-  destructuring?: ("any" | "all")
-  ignoreReadBeforeAssign?: boolean
+  excludedRunes?: string[]
+  [k: string]: unknown | undefined
 }]
 // ----- svelte/shorthand-attribute -----
 type SvelteShorthandAttribute = []|[{

packages/eslint-plugin-svelte/src/rules/prefer-const.ts

@@ -21,7 +21,7 @@ function findDeclarationCallee(node: TSESTree.Expression) {
  * Determines if a declaration should be skipped in the const preference analysis.
  * Specifically checks for Svelte's state management utilities ($props, $derived).
  */
-function shouldSkipDeclaration(declaration: TSESTree.Expression | null) {
+function shouldSkipDeclaration(declaration: TSESTree.Expression | null, excludedRunes: string[]) {
 	if (!declaration) {
 		return false;
 	}
@@ -31,15 +31,15 @@ function shouldSkipDeclaration(declaration: TSESTree.Expression | null) {
 		return false;
 	}
 
-	if (callee.type === 'Identifier' && ['$props', '$state', '$derived'].includes(callee.name)) {
+	if (callee.type === 'Identifier' && excludedRunes.includes(callee.name)) {
 		return true;
 	}
 
 	if (callee.type !== 'MemberExpression' || callee.object.type !== 'Identifier') {
 		return false;
 	}
 
-	if (callee.object.name === '$state' || callee.object.name === '$derived') {
+	if (excludedRunes.includes(callee.object.name)) {
 		return true;
 	}
 
@@ -54,16 +54,32 @@ export default createRule('prefer-const', {
 			category: 'Best Practices',
 			recommended: false,
 			extensionRule: 'prefer-const'
-		}
+		},
+		schema: [
+			{
+				type: 'object',
+				properties: {
+					excludedRunes: {
+						type: 'array',
+						items: {
+							type: 'string'
+						}
+					}
+				}
+			}
+		]
 	},
 	create(context) {
+		const config = context.options[0] ?? {};
+		const excludedRunes = config.excludedRunes ?? ['$props', '$derived'];
+
 		return defineWrapperListener(coreRule, context, {
 			createListenerProxy(coreListener) {
 				return {
 					...coreListener,
 					VariableDeclaration(node) {
 						for (const decl of node.declarations) {
-							if (shouldSkipDeclaration(decl.init)) {
+							if (shouldSkipDeclaration(decl.init, excludedRunes)) {
 								return;
 							}
 						}

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option1/_config.json

@@ -0,0 +1,3 @@
+{
+	"options": [{ "excludedRunes": [] }]
+}

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option1/test01-errors.yaml

@@ -0,0 +1,20 @@
+- message: "'prop1' is never reassigned. Use 'const' instead."
+  line: 2
+  column: 8
+  suggestions: null
+- message: "'prop2' is never reassigned. Use 'const' instead."
+  line: 2
+  column: 15
+  suggestions: null
+- message: "'zero' is never reassigned. Use 'const' instead."
+  line: 3
+  column: 6
+  suggestions: null
+- message: "'derived' is never reassigned. Use 'const' instead."
+  line: 4
+  column: 6
+  suggestions: null
+- message: "'derivedBy' is never reassigned. Use 'const' instead."
+  line: 5
+  column: 6
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option1/test01-input.svelte

@@ -0,0 +1,6 @@
+<script>
+	let { prop1, prop2 } = $props();
+	let zero = $state(0);
+	let derived = $derived(zero * 2);
+	let derivedBy = $derived.by(calc());
+</script>

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option1/test01-output.svelte

@@ -0,0 +1,6 @@
+<script>
+	const { prop1, prop2 } = $props();
+	const zero = $state(0);
+	const derived = $derived(zero * 2);
+	const derivedBy = $derived.by(calc());
+</script>

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option2/_config.json

@@ -0,0 +1,3 @@
+{
+	"options": [{ "excludedRunes": ["$state"] }]
+}

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option2/test01-errors.yaml

@@ -0,0 +1,16 @@
+- message: "'prop1' is never reassigned. Use 'const' instead."
+  line: 2
+  column: 8
+  suggestions: null
+- message: "'prop2' is never reassigned. Use 'const' instead."
+  line: 2
+  column: 15
+  suggestions: null
+- message: "'derived' is never reassigned. Use 'const' instead."
+  line: 4
+  column: 6
+  suggestions: null
+- message: "'derivedBy' is never reassigned. Use 'const' instead."
+  line: 5
+  column: 6
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option2/test01-input.svelte

@@ -0,0 +1,6 @@
+<script>
+	let { prop1, prop2 } = $props();
+	let zero = $state(0);
+	let derived = $derived(zero * 2);
+	let derivedBy = $derived.by(calc());
+</script>

packages/eslint-plugin-svelte/tests/fixtures/rules/prefer-const/invalid/option2/test01-output.svelte

@@ -0,0 +1,6 @@
+<script>
+	const { prop1, prop2 } = $props();
+	let zero = $state(0);
+	const derived = $derived(zero * 2);
+	const derivedBy = $derived.by(calc());
+</script>