Added unit test for __main__

tests/test_main.py

@@ -0,0 +1,17 @@
+import unittest
+
+from unittest.mock import patch
+
+from wavinfo.__main__ import main
+
+import sys
+
+class MainTest(unittest.TestCase):
+    
+    def test_empty_argv(self): 
+        with patch.object(sys, 'argv', []):
+            try:
+                main()
+            except:
+                self.fail("main() throwing an exception")
+