feat(has-lang): add option for which attributes to look at

lib/checks/language/has-lang-evaluate.js

@@ -1,17 +1,30 @@
 import { isXHTML } from '../../core/utils';
 
-function hasLangEvaluate(node) {
-	const langValue = (node.getAttribute(`lang`) || '').trim();
-	const xmlLangValue = (node.getAttribute(`xml:lang`) || '').trim();
+function hasValue(value) {
+	return (value || '').trim() !== '';
+}
 
-	if (!langValue && xmlLangValue && !isXHTML(document)) {
+function hasLangEvaluate(node, options, virtualNode) {
+	// special case when xml:lang has a value and lang does not
+	// but the document is not XHTML
+	if (
+		options.attributes.includes('xml:lang') &&
+		options.attributes.includes('lang') &&
+		hasValue(virtualNode.attr('xml:lang')) &&
+		!hasValue(virtualNode.attr('lang')) &&
+		!isXHTML(document)
+	) {
 		this.data({
 			messageKey: 'noXHTML'
 		});
 		return false;
 	}
 
-	if (!(langValue || xmlLangValue)) {
+	const hasLang = options.attributes.some(name => {
+		return hasValue(virtualNode.attr(name));
+	});
+
+	if (!hasLang) {
 		this.data({
 			messageKey: 'noLang'
 		});

lib/checks/language/has-lang.json

@@ -1,6 +1,9 @@
 {
 	"id": "has-lang",
 	"evaluate": "has-lang-evaluate",
+	"options": {
+		"attributes": ["lang", "xml:lang"]
+	},
 	"metadata": {
 		"impact": "serious",
 		"messages": {

test/checks/language/has-lang.js

@@ -45,4 +45,12 @@ describe('has-lang', function() {
 		assert.isFalse(hasLangEvaluate.apply(checkContext, params));
 		assert.equal(checkContext._data.messageKey, 'noLang');
 	});
+
+	it('should support options.attributes', function() {
+		var params = checkSetup('<div id="target" foo="cats"></div>', {
+			attributes: ['foo']
+		});
+
+		assert.isTrue(hasLangEvaluate.apply(checkContext, params));
+	});
 });