Fix for highlightjs#1868

src/highlight.js

@@ -707,8 +707,8 @@ https://highlightjs.org/
   }
 
   function autoDetection(name) {
-    name = (name || '').toLowerCase();
-    return !languages[name].disableAutodetect;
+    lang = getLanguage(name);
+    return lang && !lang.disableAutodetect;
   }
 
   /* Interface definition */

test/api/autoDetection.js

@@ -0,0 +1,36 @@
+'use strict';
+
+let hljs   = require('../../build');
+let should = require('should');
+
+describe('.autoDetection()', function() {
+  it('should get an existing language', function() {
+    const result = hljs.autoDetection('python');
+
+    result.should.be.instanceOf(Object);
+  });
+
+  it('should get an existing language by alias', function() {
+    const result = hljs.autoDetection('py');
+
+    result.should.be.instanceOf(Object);
+  });
+
+  it('should be case insensitive', function() {
+    const result = hljs.autoDetection('pYTHOn');
+
+    result.should.be.instanceOf(Object);
+  });
+
+  it('should return undefined', function() {
+    const result = hljs.autoDetection('-impossible-');
+
+    should.strictEqual(result, undefined);
+  });
+
+  it('should not break on undefined', function() {
+    const result = hljs.autoDetection(undefined);
+
+    should.strictEqual(result, undefined);
+  });
+});

test/api/getLanguage.js

@@ -10,6 +10,12 @@ describe('.getLanguage()', function() {
     result.should.be.instanceOf(Object);
   });
 
+  it('should get an existing language by alias', function() {
+    const result = hljs.getLanguage('py');
+
+    result.should.be.instanceOf(Object);
+  });
+
   it('should be case insensitive', function() {
     const result = hljs.getLanguage('pYTHOn');
 

test/api/index.js

@@ -8,6 +8,7 @@ describe('hljs', function() {
   require('./binaryNumber');
   require('./starters');
   require('./getLanguage');
+  require('./autoDetection');
   require('./highlight');
   require('./fixmarkup');
 });