start make tests

tests/test_app.py

@@ -0,0 +1,16 @@
+from argenta.app import App
+from argenta.app.exceptions import (InvalidDescriptionMessagePatternException,
+                                    NoRegisteredRoutersException)
+
+import unittest
+
+
+class TestApp(unittest.TestCase):
+    def test_set_invalid_description_message_pattern(self):
+        with self.assertRaises(InvalidDescriptionMessagePatternException):
+            App().set_description_message_pattern('Invalid des{}cription pattern')
+
+    def test_no_registered_router(self):
+        with self.assertRaises(NoRegisteredRoutersException):
+            App()._validate_number_of_routers()
+