add static test for main

tests/__main__.py

@@ -3,6 +3,7 @@ import unittest
 from .compatibility_test import TestCompat
 from .transaction_test import TestTransaction
 from .variable_test import TestVariables
+from .main_test import TestMain
 
 if __name__ == "__main__":
     unittest.main()

tests/main_test.py

@@ -0,0 +1,9 @@
+import unittest
+import sys
+sys.path.append("..")
+
+class TestMain(unittest.TestCase):
+    def test_main(self):
+        import main
+if __name__ == "__main__":
+    unittest.main()