add a testsuite checking the aspect ration computation

diff --git a/tests.py b/tests.py
new file mode 100755 (executable)
index 0000000..5a48857
--- /dev/null
+++ b/tests.py
@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+import unittest
+import screen
+
+class TestResolutions(unittest.TestCase):
+
+  def test_ratio(self):
+      # check whether a few aspect ratios are printed as expected
+      self.assertEqual(str(screen.Resolution(1024, 768)), '1024x768 (4:3)')
+      self.assertTrue(str(screen.Resolution(1280, 1024)) in ('1280x1024 (5:4)', '1280x1024 (4:3)'))
+      self.assertEqual(str(screen.Resolution(1366, 768)), '1366x768 (16:9)')
+      self.assertEqual(str(screen.Resolution(1920, 1080)), '1920x1080 (16:9)')
+      self.assertEqual(str(screen.Resolution(1920, 1200)), '1920x1200 (16:10)')
+
+if __name__ == '__main__':
+    unittest.main()