Tests for observer patt. can run in random order

Author: gyermolenko

tests/behavioral/test_observer.py

@@ -1,58 +1,29 @@
-import unittest
-from unittest.mock import patch
-
-from patterns.behavioral.observer import Subject, Data, DecimalViewer, HexViewer
-
-
-class TestSubject(unittest.TestCase):
-    @classmethod
-    def setUpClass(cls):
-        cls.s = Subject()
-        cls.dec_obs = DecimalViewer()
-        cls.hex_obs = HexViewer()
-
-    def test_a_observer_list_shall_be_empty_initially(cls):
-        cls.assertEqual(len(cls.s._observers), 0)
-
-    def test_b_observers_shall_be_attachable(cls):
-        cls.s.attach(cls.dec_obs)
-        cls.assertEqual(isinstance(cls.s._observers[0], DecimalViewer), True)
-        cls.assertEqual(len(cls.s._observers), 1)
-        cls.s.attach(cls.hex_obs)
-        cls.assertEqual(isinstance(cls.s._observers[1], HexViewer), True)
-        cls.assertEqual(len(cls.s._observers), 2)
-
-    def test_c_observers_shall_be_detachable(cls):
-        cls.s.detach(cls.dec_obs)
-        # hex viewer shall be remaining if dec viewer is detached first
-        cls.assertEqual(isinstance(cls.s._observers[0], HexViewer), True)
-        cls.assertEqual(len(cls.s._observers), 1)
-        cls.s.detach(cls.hex_obs)
-        cls.assertEqual(len(cls.s._observers), 0)
-
-
-class TestData(unittest.TestCase):
-    @classmethod
-    def setUpClass(cls):
-        cls.dec_obs = DecimalViewer()
-        cls.hex_obs = HexViewer()
-        cls.sub = Data('Data')
-        # inherited behavior already tested with TestSubject
-        cls.sub.attach(cls.dec_obs)
-        cls.sub.attach(cls.hex_obs)
-
-    def test_data_change_shall_notify_all_observers_once(cls):
-        with patch.object(cls.dec_obs, 'update') as mock_dec_obs_update, patch.object(
-            cls.hex_obs, 'update'
-        ) as mock_hex_obs_update:
-            cls.sub.data = 10
-            cls.assertEqual(mock_dec_obs_update.call_count, 1)
-            cls.assertEqual(mock_hex_obs_update.call_count, 1)
-
-    def test_data_value_shall_be_changeable(cls):
-        cls.sub.data = 20
-        cls.assertEqual(cls.sub._data, 20)
-
-    def test_data_name_shall_be_changeable(cls):
-        cls.sub.name = 'New Data Name'
-        cls.assertEqual(cls.sub.name, 'New Data Name')
+from unittest.mock import patch, Mock
+
+import pytest
+
+from patterns.behavioral.observer import Data, DecimalViewer, HexViewer
+
+
+@pytest.fixture
+def observable():
+    return Data('some data')
+
+def test_attach_detach(observable):
+    decimal_viewer = DecimalViewer()
+    assert len(observable._observers) == 0
+
+    observable.attach(decimal_viewer)
+    assert decimal_viewer in observable._observers
+
+    observable.detach(decimal_viewer)
+    assert decimal_viewer not in observable._observers
+
+def test_one_data_change_notifies_each_observer_once(observable):
+    observable.attach(DecimalViewer())
+    observable.attach(HexViewer())
+
+    with patch('patterns.behavioral.observer.DecimalViewer.update', new_callable=Mock()) as mocked_update:
+        assert mocked_update.call_count == 0
+        observable.data = 10
+        assert mocked_update.call_count == 1