add test for setable time

ebu_tt_live/clocks/base.py

@@ -66,7 +66,7 @@ def set_fixed_time_mode(self, value):
         """
         if not isinstance(value, bool):
             raise TypeError
-        self.use_saved_time = value
+        self._use_fixed_time = value
 
     def is_fixed_time_mode(self):
         """

ebu_tt_live/clocks/test/test_base.py

@@ -0,0 +1,17 @@
+
+from unittest import TestCase
+from ebu_tt_live.clocks.base import Clock
+from datetime import timedelta
+
+
+class TestLocalClock(TestCase):
+
+    def test_fixed_time_case(self):
+        clock = Clock()
+        test_time = timedelta(hours=1)
+        clock.set_fixed_time(test_time)
+        clock.set_fixed_time_mode(True)
+        self.assertEqual(clock.get_time(), test_time)
+        clock.set_fixed_time_mode(False)
+        self.assertRaises(NotImplementedError, lambda: clock.get_time())
+        self.assertRaises(TypeError, lambda: clock.set_fixed_time(1))