Initial commit

tests/test_observable.py

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+import pytest
+
+from myutils.observable import NotObservableError, make_observable, bind
+
+
+# Test fixtures
+class Demo:
+  def __init__(self):
+    self.number = 1
+  
+  def get_double(self):
+    return self.number * 2
+
+
+# Tests
+def test_i_can_make_an_object_observable():
+  demo = Demo()
+  result = make_observable(demo)
+  
+  assert hasattr(demo, '_listeners')
+  assert isinstance(demo._listeners, dict)
+  assert result is demo
+
+
+def test_i_can_bind_a_callback_to_an_attribute():
+  demo = Demo()
+  make_observable(demo)
+  
+  callback = lambda old, new: None
+  bind(demo, 'number', callback)
+  
+  assert 'number' in demo._listeners
+  assert callback in demo._listeners['number']
+
+
+def test_i_can_receive_notification_when_attribute_changes():
+  demo = Demo()
+  make_observable(demo)
+  
+  called = []
+  bind(demo, 'number', lambda old, new: called.append(True))
+  
+  demo.number = 5
+  
+  assert len(called) == 1
+
+
+def test_i_can_receive_old_and_new_values_in_callback():
+  demo = Demo()
+  make_observable(demo)
+  
+  values = []
+  bind(demo, 'number', lambda old, new: values.append((old, new)))
+  
+  demo.number = 5
+  demo.number = 10
+  
+  assert values == [(1, 5), (5, 10)]
+
+
+def test_i_can_bind_multiple_callbacks_to_same_attribute():
+  demo = Demo()
+  make_observable(demo)
+  
+  calls1 = []
+  calls2 = []
+  bind(demo, 'number', lambda old, new: calls1.append(new))
+  bind(demo, 'number', lambda old, new: calls2.append(new))
+  
+  demo.number = 5
+  
+  assert calls1 == [5]
+  assert calls2 == [5]
+
+
+def test_i_can_bind_callbacks_to_different_attributes():
+  demo = Demo()
+  make_observable(demo)
+  
+  number_calls = []
+  name_calls = []
+  bind(demo, 'number', lambda old, new: number_calls.append(new))
+  bind(demo, 'name', lambda old, new: name_calls.append(new))
+  
+  demo.number = 5
+  demo.name = "test"
+  
+  assert number_calls == [5]
+  assert name_calls == ["test"]
+
+
+def test_i_can_modify_non_observed_attributes_without_notification():
+  demo = Demo()
+  make_observable(demo)
+  
+  called = []
+  bind(demo, 'number', lambda old, new: called.append(True))
+  
+  demo.other_attr = "value"
+  
+  assert len(called) == 0
+  assert demo.other_attr == "value"
+
+
+def test_i_can_have_multiple_instances_with_independent_observers():
+  demo1 = Demo()
+  demo2 = Demo()
+  
+  make_observable(demo1)
+  
+  calls1 = []
+  bind(demo1, 'number', lambda old, new: calls1.append(new))
+  
+  demo1.number = 5
+  demo2.number = 10
+  
+  # Only demo1 should trigger callback
+  assert calls1 == [5]
+  assert demo1.number == 5
+  assert demo2.number == 10
+
+
+def test_i_can_call_make_observable_multiple_times_safely():
+  demo = Demo()
+  
+  result1 = make_observable(demo)
+  result2 = make_observable(demo)
+  
+  assert result1 is result2
+  assert hasattr(demo, '_listeners')
+  
+  # Should still work normally
+  called = []
+  bind(demo, 'number', lambda old, new: called.append(new))
+  demo.number = 5
+  
+  assert len(called) == 1
+
+
+def test_i_cannot_bind_before_making_observable():
+  demo = Demo()
+  
+  with pytest.raises(NotObservableError) as exc_info:
+    bind(demo, 'number', lambda old, new: None)
+  
+  assert "must be made observable" in str(exc_info.value).lower()
+
+
+def test_i_can_set_attribute_that_does_not_exist_yet():
+  demo = Demo()
+  make_observable(demo)
+  
+  values = []
+  bind(demo, 'new_attr', lambda old, new: values.append((old, new)))
+  
+  demo.new_attr = "first_value"
+  
+  assert values == [(None, "first_value")]
+  assert demo.new_attr == "first_value"
+
+
+def test_i_can_preserve_original_class_behavior():
+  demo = Demo()
+  make_observable(demo)
+  
+  # Test that original methods still work
+  assert demo.get_double() == 2
+  
+  demo.number = 5
+  assert demo.get_double() == 10
+  
+  # Test that isinstance still works
+  assert isinstance(demo, Demo)