diff --git a/tests/pattern-tests.js b/tests/pattern-tests.js
index e2031b9c10..382b6e56e5 100644
--- a/tests/pattern-tests.js
+++ b/tests/pattern-tests.js
@@ -4,6 +4,51 @@ const { assert } = require("chai");
 const PrismLoader = require('./helper/prism-loader');
 const { languages } = require('../components');
 
+
+/**
+ * Performs a breadth-first search on the given start element.
+ *
+ * @param {any} start
+ * @param {(path: { key: string, value: any }[]) => void} callback
+ */
+function BFS(start, callback) {
+	const visited = new Set();
+	/** @type {{ key: string, value: any }[][]} */
+	let toVisit = [
+		[{ key: null, value: start }]
+	];
+
+	callback(toVisit[0]);
+
+	while (toVisit.length > 0) {
+		/** @type {{ key: string, value: any }[][]} */
+		const newToVisit = [];
+
+		for (const path of toVisit) {
+			const obj = path[path.length - 1].value;
+			if (!visited.has(obj)) {
+				visited.add(obj);
+
+				for (const key in obj) {
+					const value = obj[key];
+
+					path.push({ key, value });
+					callback(path);
+
+					if (Array.isArray(value) || Object.prototype.toString.call(value) == '[object Object]') {
+						newToVisit.push([...path]);
+					}
+
+					path.pop();
+				}
+			}
+		}
+
+		toVisit = newToVisit;
+	}
+}
+
+
 for (const lang in languages) {
 	if (lang === 'meta') {
 		continue;
@@ -13,23 +58,61 @@ for (const lang in languages) {
 
 		const Prism = PrismLoader.createInstance(lang);
 
-		it('- should not match the empty string', function () {
-			let lastToken = '<unknown>';
+		/**
+		 * Invokes the given function on every pattern in `Prism.languages`.
+		 *
+		 * @param {(values: { pattern: RegExp, tokenPath: string, name: string, parent: any, path: { key: string, value: any }[] }) => void} callback
+		 */
+		function forEachPattern(callback) {
+			BFS(Prism.languages, path => {
+				const { key, value } = path[path.length - 1];
 
-			Prism.languages.DFS(Prism.languages, function (name, value) {
-				if (typeof this === 'object' && !Array.isArray(this) && name !== 'pattern') {
-					lastToken = name;
+				let tokenPath = '<languages>';
+				for (const { key } of path) {
+					if (!key) {
+						// do nothing
+					} else if (/^\d+$/.test(key)) {
+						tokenPath += `[${key}]`;
+					} else if (/^[a-z]\w*$/i.test(key)) {
+						tokenPath += `.${key}`;
+					} else {
+						tokenPath += `[${JSON.stringify(key)}]`;
+					}
 				}
 
-				if (Prism.util.type(value) === 'RegExp') {
-					assert.notMatch('', value, `Token '${lastToken}': ${value} should not match the empty string.`);
+				if (Object.prototype.toString.call(value) == '[object RegExp]') {
+					callback({
+						pattern: value,
+						tokenPath,
+						name: key,
+						parent: path.length > 1 ? path[path.length - 2].value : undefined,
+						path,
+					});
 				}
 			});
+		}
+
+
+		it('- should not match the empty string', function () {
+			forEachPattern(({ pattern, tokenPath }) => {
+				// test for empty string
+				assert.notMatch('', pattern, `Token ${tokenPath}: ${pattern} should not match the empty string.`);
+			});
 		});
 
-		it('- should have nice names and aliases', function () {
-			let lastToken = '<unknown>';
+		it('- should have a capturing group if lookbehind is set to true', function () {
+			forEachPattern(({ pattern, tokenPath, name, parent }) => {
+				if (name === 'pattern' && parent.lookbehind) {
+					const simplifiedSource = pattern.source.replace(/\\\D/g, '_').replace(/\[[^\]]*\]/g, '_');
 
+					if (!/\((?!\?)/.test(simplifiedSource)) {
+						assert.fail(`Token ${tokenPath}: The pattern is set to 'lookbehind: true' but does not have a capturing group.`);
+					}
+				}
+			});
+		});
+
+		it('- should have nice names and aliases', function () {
 			const niceName = /^[a-z][a-z\d]*(?:[-_][a-z\d]+)*$/;
 			function testName(name, desc = 'token name') {
 				if (!niceName.test(name)) {
@@ -37,20 +120,25 @@ for (const lang in languages) {
 				}
 			}
 
-			Prism.languages.DFS(Prism.languages, function (name, value) {
-				if (typeof this === 'object' && !Array.isArray(this) && name !== 'pattern') {
-					lastToken = name;
+			forEachPattern(({ name, parent, tokenPath, path }) => {
+				// token name
+				let offset = 1;
+				if (name == 'pattern') { // regex can be inside an object
+					offset++;
 				}
-
-				if (Prism.util.type(value) === 'RegExp') {
-					testName(lastToken);
+				if (Array.isArray(path[path.length - 1 - offset].value)) { // regex/regex object can be inside an array
+					offset++;
 				}
+				const patternName = path[path.length - offset].key;
+				testName(patternName);
 
-				if (name === 'alias') {
-					if (typeof value === 'string') {
-						testName(value, `alias of '${lastToken}'`);
-					} else if (Array.isArray(value)) {
-						value.forEach(name => testName(name, `alias of '${lastToken}'`));
+				// check alias
+				if (name == 'pattern' && 'alias' in parent) {
+					const alias = parent.alias;
+					if (typeof alias === 'string') {
+						testName(alias, `alias of '${tokenPath}'`);
+					} else if (Array.isArray(alias)) {
+						alias.forEach(name => testName(name, `alias of '${tokenPath}'`));
 					}
 				}
 			});