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import pytest |
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@pytest.fixture |
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def subclass_registry_metaclass(): |
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from so_magic.utils import SubclassRegistry |
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return SubclassRegistry |
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@pytest.fixture |
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def assert_correct_class_creation(subclass_registry_metaclass): |
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def assert_class_creation(user_class): |
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assert type(user_class) == subclass_registry_metaclass |
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assert hasattr(user_class, 'subclasses') |
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assert hasattr(user_class, 'create') |
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assert hasattr(user_class, 'register_as_subclass') |
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assert user_class.subclasses == {} |
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return assert_class_creation |
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def test_metaclass_usage(subclass_registry_metaclass, assert_correct_class_creation): |
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class ParentClass(metaclass=subclass_registry_metaclass): |
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pass |
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assert_correct_class_creation(ParentClass) |
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@pytest.fixture |
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def usage_with_subclass(subclass_registry_metaclass): |
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def parent_n_child_classes(): |
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class ParentClass(metaclass=subclass_registry_metaclass): |
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pass |
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@ParentClass.register_as_subclass('child1') |
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class Child1(ParentClass): |
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pass |
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child1_instance1 = ParentClass.create('child1') |
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assert ParentClass.subclasses['child1'] == Child1 |
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assert type(child1_instance1) == Child1 |
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assert isinstance(child1_instance1, Child1) |
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assert isinstance(child1_instance1, ParentClass) |
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return child1_instance1, Child1, ParentClass |
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return parent_n_child_classes |
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@pytest.fixture |
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def plain_usage(subclass_registry_metaclass): |
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def parent_n_child_classes(): |
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class ParentClass2(metaclass=subclass_registry_metaclass): |
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pass |
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@ParentClass2.register_as_subclass('child2') |
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class Child2: |
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pass |
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child1_instance2 = ParentClass2.create('child2') |
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assert ParentClass2.subclasses['child2'] == Child2 |
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assert type(child1_instance2) == Child2 |
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assert isinstance(child1_instance2, Child2) |
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assert not isinstance(child1_instance2, ParentClass2) |
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return child1_instance2, Child2, ParentClass2 |
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return parent_n_child_classes |
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def test_subclass_registry(usage_with_subclass, plain_usage): |
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child1_instance1, Child1, ParentClass = usage_with_subclass() |
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non_existent_identifier = 'child2' |
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exception_message_regex = \ |
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f'Bad "{str(ParentClass.__name__)}" subclass request; requested subclass with identifier ' \ |
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f'{non_existent_identifier}, but known identifiers are ' \ |
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rf'\[{", ".join(subclass_identifier for subclass_identifier in ParentClass.subclasses.keys())}\]' |
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with pytest.raises(ValueError, match=exception_message_regex): |
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ParentClass.create(non_existent_identifier) |
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child1_instance2, Child2, ParentClass2 = plain_usage() |
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assert ParentClass.subclasses['child1'] == Child1 |
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