add unit testing via 'make test'

tests/test.py

@@ -0,0 +1,21 @@
+
+from unittest import TestCase
+
+from labelImg import get_main_app
+
+
+class TestMainWindow(TestCase):
+
+    app = None
+    win = None
+
+    def setUp(self):
+        self.app, self.win = get_main_app()
+
+    def tearDown(self):
+        self.win.close()
+        self.app.quit()
+
+    def test_noop(self):
+        pass
+