feat(prefer-svelte-reactivity): ignoring variables encapsulated in functions

Author: marekdedic

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

@@ -12,7 +12,18 @@ export default createRule('prefer-svelte-reactivity', {
 			category: 'Possible Errors',
 			recommended: true
 		},
-		schema: [],
+		schema: [
+			{
+				type: 'object',
+				properties: {
+					ignoreEncapsulatedLocalVariables: {
+						type: 'boolean',
+						default: true
+					}
+				},
+				additionalProperties: false
+			}
+		],
 		messages: {
 			mutableDateUsed:
 				'Found a mutable instance of the built-in Date class. Use SvelteDate instead.',
@@ -31,6 +42,8 @@ export default createRule('prefer-svelte-reactivity', {
 		]
 	},
 	create(context) {
+		const ignoreEncapsulatedLocalVariables =
+			context.options[0]?.ignoreEncapsulatedLocalVariables ?? true;
 		const returnedVariables: Map<
 			TSESTree.ArrowFunctionExpression | TSESTree.FunctionDeclaration,
 			TSESTree.VariableDeclarator[]
@@ -122,6 +135,9 @@ export default createRule('prefer-svelte-reactivity', {
 							});
 						}
 					}
+					if (ignoreEncapsulatedLocalVariables && isEncapsulated(returnedVariables, node)) {
+						continue;
+					}
 					for (const returnedVar of Array.from(returnedVariables.values()).flat()) {
 						if (isIn(node, returnedVar)) {
 							context.report({
@@ -198,6 +214,22 @@ function findEnclosingFunction(
 	return findAncestorOfTypes(node, ['ArrowFunctionExpression', 'FunctionDeclaration']);
 }
 
+function isEncapsulated(
+	returnedVariables: Map<
+		TSESTree.ArrowFunctionExpression | TSESTree.FunctionDeclaration,
+		TSESTree.VariableDeclarator[]
+	>,
+	node: TSESTree.Node
+): boolean {
+	const enclosingFunction = findEnclosingFunction(node);
+	if (enclosingFunction === null) {
+		return false;
+	}
+	return (
+		returnedVariables.get(enclosingFunction)?.some((variable) => isIn(node, variable)) === false
+	);
+}
+
 function isDateMutable(referenceTracker: ReferenceTracker, ctorNode: TSESTree.Expression): boolean {
 	return !referenceTracker
 		.iteratePropertyReferences(ctorNode, {