diff --git a/readme.rst b/readme.rst
index 1afbfbc..e9def63 100644
--- a/readme.rst
+++ b/readme.rst
@@ -48,4 +48,4 @@ Install dependencies:
 
 Run tests:
 
-``cd rplugin && python -m unittest test.test_neotags``
+``docker run -it --rm -v $PWD/rplugin:/project -w /project registry.gitlab.com/danielsiepmann/neotags:latest python -m unittest test.test_neotags``
diff --git a/rplugin/test/test_neotags.py b/rplugin/test/test_neotags.py
index af2766d..9dfc5f8 100644
--- a/rplugin/test/test_neotags.py
+++ b/rplugin/test/test_neotags.py
@@ -1,3 +1,4 @@
+import unittest
 from unittest.mock import Mock
 from unittest.mock import MagicMock
 from pyfakefs import fake_filesystem_unittest
@@ -6,7 +7,6 @@ import os
 
 from python3.neotags import NeotagsPlugin
 
-
 class TestNeotagsPlugin(fake_filesystem_unittest.TestCase):
 
     def setUp(self):
@@ -18,22 +18,42 @@ class TestNeotagsPlugin(fake_filesystem_unittest.TestCase):
         self.plugin = NeotagsPlugin(Mock(pynvim.api.nvim))
 
     def test_default_options(self):
-        self.assertEqual('ctags', self.plugin.options['ctags_cmd'])
         self.assertEqual('tags', self.plugin.options['tags_filename'])
+        self.assertEqual('ctags', self.plugin.options['ctags_cmd'])
         self.assertEqual(False, self.plugin.options['logging'])
 
     def test_custom_options(self):
-        self.plugin.nvim.configure_mock(vars={})
-        self.plugin.nvim.vars['neotags_tags_filename'] = 'new_tags'
-        self.plugin.nvim.vars['neotags_ctags_cmd'] = 'new_ctags'
-        self.plugin.nvim.vars['neotags_logging'] = True
+        def eval(argument):
+            if argument == 'g:neotags_tags_filename':
+                return 'new_tags'
+            if argument == 'g:neotags_ctags_cmd':
+                return 'new_ctags'
+            if argument == 'g:neotags_logging':
+                return True
 
+        self.plugin.nvim.configure_mock(eval=eval)
         self.plugin.update_settings()
 
         self.assertEqual('new_tags', self.plugin.options['tags_filename'])
         self.assertEqual('new_ctags', self.plugin.options['ctags_cmd'])
         self.assertEqual(True, self.plugin.options['logging'])
 
+    def test_fallback_option(self):
+        def eval(argument):
+            if argument == 'g:neotags_tags_filename':
+                return 'new_tags'
+            if argument == 'g:neotags_ctags_cmd':
+                raise pynvim.api.nvim.NvimError('')
+            if argument == 'g:neotags_logging':
+                return True
+
+        self.plugin.nvim.configure_mock(eval=eval)
+        self.plugin.update_settings()
+
+        self.assertEqual('new_tags', self.plugin.options['tags_filename'])
+        self.assertEqual('ctags', self.plugin.options['ctags_cmd'])
+        self.assertEqual(True, self.plugin.options['logging'])
+
     def test_debug_logs_to_nvim_when_logging_is_active(self):
         self.plugin.options['logging'] = True
         self.plugin.nvim.out_write = MagicMock()
@@ -128,3 +148,6 @@ class TestNeotagsPlugin(fake_filesystem_unittest.TestCase):
         self.plugin.strip_existing_tags(tags_file, os.path.basename(filename))
         with open(tags_file) as f, open(expected_tags_file) as e:
             self.assertEqual(e.read(), f.read())
+
+if __name__ == '__main__':
+    unittest.main()