diff --git a/src/utils/__tests__/openapi.test.ts b/src/utils/__tests__/openapi.test.ts
index 8e7aa3d8..3abbcf99 100644
--- a/src/utils/__tests__/openapi.test.ts
+++ b/src/utils/__tests__/openapi.test.ts
@@ -13,6 +13,7 @@ import {
   humanizeNumberRange,
   getContentWithLegacyExamples,
   getDefinitionName,
+  langFromMime,
 } from '../';
 
 import { FieldModel, OpenAPIParser, RedocNormalizedOptions } from '../../services';
@@ -1320,4 +1321,18 @@ describe('Utils', () => {
       expect(getDefinitionName()).toBeUndefined();
     });
   });
+
+  describe('langFromMime', () => {
+    test('should return correct lang name from content type', () => {
+      expect(langFromMime('application/xml')).toEqual('xml');
+      expect(langFromMime('application/x-xml')).toEqual('xml');
+      expect(langFromMime('application/csv')).toEqual('csv');
+      expect(langFromMime('application/x-csv')).toEqual('csv');
+      expect(langFromMime('text/plain')).toEqual('tex');
+      expect(langFromMime('text/x-plain')).toEqual('tex');
+      expect(langFromMime('application/plain')).toEqual('tex');
+
+      expect(langFromMime('text/some-type')).toEqual('clike');
+    });
+  });
 });