fix: skip tests on travis

Author: dtopuzov

core_tests/unit/product/test_preview_helpers.py

@@ -9,7 +9,7 @@
 class PreviewHelperTests(unittest.TestCase):
     current_folder = os.path.dirname(os.path.realpath(__file__))
 
-    @unittest.skipIf(os.environ.get('TRAVIS', None) is not None, 'Skip on Travis.')
+    @unittest.skipIf(os.environ.get('CI', None) is not None, 'Skip on Travis.')
     def test_01_constants(self):
         text = File.read(path=os.path.join(self.current_folder, 'preview.log'))
         url = Preview.get_url(output=text)