feat: Set type for RuleDefinition.defaultOptions (#173)

Co-authored-by: Francesco Trotta <[email protected]>

Author: nzakas

packages/core/src/types.ts

@@ -141,6 +141,7 @@ export interface RulesMetaDocs {
  */
 export interface RulesMeta<
 	MessageIds extends string = string,
+	RuleOptions = unknown[],
 	ExtRuleDocs = unknown,
 > {
 	/**
@@ -158,8 +159,10 @@ export interface RulesMeta<
 	 */
 	schema?: JSONSchema4 | JSONSchema4[] | false | undefined;
 
-	/** Any default options to be recursively merged on top of any user-provided options. */
-	defaultOptions?: unknown[];
+	/**
+	 * Any default options to be recursively merged on top of any user-provided options.
+	 **/
+	defaultOptions?: RuleOptions;
 
 	/**
 	 * The messages that the rule can report.
@@ -561,7 +564,11 @@ export interface RuleDefinition<
 	/**
 	 * The meta information for the rule.
 	 */
-	meta?: RulesMeta<Options["MessageIds"], Options["ExtRuleDocs"]>;
+	meta?: RulesMeta<
+		Options["MessageIds"],
+		Options["RuleOptions"],
+		Options["ExtRuleDocs"]
+	>;
 
 	/**
 	 * Creates the visitor that ESLint uses to apply the rule during traversal.

packages/core/tests/types/types.test.ts

@@ -290,3 +290,46 @@ const testRule: RuleDefinition<{
 };
 
 testRule.meta satisfies RulesMeta | undefined;
+
+const testRuleWithInvalidDefaultOptions: RuleDefinition<{
+	LangOptions: TestLanguageOptions;
+	Code: TestSourceCode;
+	RuleOptions: [{ foo: string; bar: number }];
+	Visitor: TestRuleVisitor;
+	Node: TestNode;
+	MessageIds: "badFoo" | "wrongBar";
+	ExtRuleDocs: never;
+}> = {
+	meta: {
+		type: "problem",
+		schema: [
+			{
+				type: "object",
+				properties: {
+					foo: {
+						type: "string",
+					},
+					bar: {
+						type: "integer",
+					},
+				},
+				additionalProperties: false,
+			},
+		],
+
+		defaultOptions: [
+			{
+				foo: "always",
+				bar: 5,
+				// @ts-expect-error invalid default option "baz"
+				baz: "invalid",
+			},
+		],
+	},
+
+	create(): TestRuleVisitor {
+		return {};
+	},
+};
+
+testRuleWithInvalidDefaultOptions.meta satisfies RulesMeta | undefined;