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import typing as t |
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import pytest |
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@pytest.fixture |
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def subclass_registry_module(): |
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from software_patterns import SubclassRegistry |
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from software_patterns.subclass_registry import ( |
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InstantiationError, |
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UnknownClassError, |
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) |
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return type( |
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'M', |
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(), |
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{ |
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'SubclassRegistry': SubclassRegistry, |
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'InstantiationError': InstantiationError, |
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'UnknownClassError': UnknownClassError, |
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}, |
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) |
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@pytest.fixture |
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def register_class(): |
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from software_patterns import SubclassRegistry |
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def _register_class(subclass_id: str, inherit=False): |
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class ParentClass(metaclass=SubclassRegistry): |
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pass |
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if inherit: |
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@ParentClass.register_as_subclass(subclass_id) |
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class Child1(ParentClass): |
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pass |
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else: |
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@ParentClass.register_as_subclass(subclass_id) |
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class Child2: |
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pass |
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child_instance: t.Any = ParentClass.create(subclass_id) |
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return { |
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'class_registry': ParentClass, |
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'child': ParentClass.subclasses[subclass_id], |
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'child_instance': child_instance, |
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} |
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return _register_class |
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@pytest.fixture |
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def use_metaclass(register_class, assert_correct_metaclass_behaviour): |
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inherited_from_parent = { |
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True: lambda classes: isinstance(classes['child_instance'], classes['class_registry']), |
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False: lambda classes: not isinstance( |
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classes['child_instance'], classes['class_registry'] |
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), |
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} |
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def _use_metaclass_in_scenario(subclass_id: str, inherit=False): |
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classes = register_class(subclass_id, inherit=inherit) |
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assert_correct_metaclass_behaviour(classes, subclass_id) |
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assert bool(inherited_from_parent[inherit]) |
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return classes['child_instance'], classes['child'], classes['class_registry'] |
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return _use_metaclass_in_scenario |
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@pytest.fixture |
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def assert_correct_metaclass_behaviour(): |
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def assert_metaclass_behaviour(classes, subclass_id): |
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assert classes['class_registry'].subclasses[subclass_id] == classes['child'] |
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assert type(classes['child_instance']) == classes['child'] |
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assert isinstance(classes['child_instance'], classes['child']) |
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return assert_metaclass_behaviour |
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84
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def test_metaclass_usage(): |
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from software_patterns import SubclassRegistry |
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87
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class ParentClass(metaclass=SubclassRegistry): |
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pass |
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assert type(ParentClass) == SubclassRegistry |
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assert hasattr(ParentClass, 'subclasses') |
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assert hasattr(ParentClass, 'create') |
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assert hasattr(ParentClass, 'register_as_subclass') |
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assert ParentClass.subclasses == {} |
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96
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97
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def test_subclass_registry(use_metaclass, subclass_registry_module): |
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child1_instance1, Child1, ParentClass = use_metaclass('child1', inherit=True) |
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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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) |
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107
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108
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with pytest.raises( |
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subclass_registry_module.UnknownClassError, match=exception_message_regex |
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): |
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ParentClass.create(non_existent_identifier) |
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113
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child1_instance2, Child2, ParentClass2 = use_metaclass('child2', inherit=False) |
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assert ParentClass.subclasses['child1'] == Child1 |
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116
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117
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def test_create_wrong_input(): |
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from software_patterns import SubclassRegistry |
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from software_patterns.subclass_registry import InstantiationError |
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120
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121
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class ClassRegistry(metaclass=SubclassRegistry): |
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pass |
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123
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124
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@ClassRegistry.register_as_subclass('id-1') |
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class ConcreteClassA: |
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pass |
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127
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128
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@ClassRegistry.register_as_subclass('id-2') |
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class ConcreteClassB: |
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def __init__(self, a): |
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self.a = a |
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132
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133
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with pytest.raises(InstantiationError): |
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ClassRegistry.create('id-1', 'extra-argument') |
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135
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136
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with pytest.raises(InstantiationError): |
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ClassRegistry.create('id-1', extra_key='extra-kwarg') |
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138
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139
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ClassRegistry.create('id-2', 'argument-a-provided') |
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140
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with pytest.raises(InstantiationError): |
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ClassRegistry.create('id-2') |
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boromir674 /
software-patterns
