fix tests by adding validation logic for rules

index.js

@@ -18,7 +18,7 @@ const addNamespace = util.deprecate((namespace, namespaces) => {
 		namespaces.push(namespace);
 	}
 }, 'Using the "namespace" option of @namics/stylelint-bem is deprecated. ' +
-'Please use the new namespaces option which allows using multiple namespaces');
+	'Please use the new namespaces option which allows using multiple namespaces');
 
 module.exports = stylelint.createPlugin(ruleName, (options) => {
 	options = options || '';
@@ -176,13 +176,28 @@ module.exports = stylelint.createPlugin(ruleName, (options) => {
 			return `use the ${getValidSyntax(className, namespaces)} syntax`;
 		}
 	}
-
+	const isString = (val) => typeof val === 'string' || val instanceof String;
 	return (root, result) => {
+		let possible;
+		if (options === true || options === false) {
+			possible = [true, false];
+		} else {
+			possible = {
+				patternPrefixes: [isString],
+				helperPrefixes: [isString],
+				namespaces: [isString],
+				namespace: isString,
+			};
+		}
+
 		const validOptions = stylelint.utils.validateOptions(
 			result,
 			ruleName,
-			{ actual: options },
-		);
+			{
+				actual: options,
+				optional: true,
+				possible,
+			});
 
 		if (!validOptions) {
 			return;

test/invalid-config.test.js

@@ -0,0 +1,40 @@
+const { ruleName } = require('../index');
+
+testRule({
+	ruleName,
+	config: {
+		invalidKey: 'string',
+	},
+	reject: [
+		{
+			code: '.test {}',
+			message: `Invalid option name "invalidKey" for rule "${ruleName}"`,
+		},
+	],
+});
+
+testRule({
+	ruleName,
+	config: {
+		namespace: true,
+	},
+	reject: [
+		{
+			code: '.test {}',
+			message: `Invalid value "true" for option "namespace" of rule "${ruleName}"`,
+		},
+	],
+});
+
+testRule({
+	ruleName,
+	config: {
+		patternPrefixes: 42,
+	},
+	reject: [
+		{
+			code: '.test {}',
+			message: `Invalid value "42" for option "patternPrefixes" of rule "${ruleName}"`,
+		},
+	],
+});