Passed
Pull Request — dev (#30)
by Konstantinos
03:15 queued 01:38
created

subclass_registry_metaclass()   A

Complexity

Conditions 1

Size

Total Lines 4
Code Lines 4

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 1
eloc 4
nop 0
dl 0
loc 4
rs 10
c 0
b 0
f 0
1
import pytest
2
3
4
@pytest.fixture
5
def subclass_registry_metaclass():
6
    from so_magic.utils import SubclassRegistry
7
    return SubclassRegistry
8
9
10
@pytest.fixture
11
def assert_correct_class_creation(subclass_registry_metaclass):
12
    def assert_class_creation(user_class):
13
        assert type(user_class) == subclass_registry_metaclass
14
        assert hasattr(user_class, 'subclasses')
15
        assert hasattr(user_class, 'create')
16
        assert hasattr(user_class, 'register_as_subclass')
17
        assert user_class.subclasses == {}
18
    return assert_class_creation
19
20
21
def test_metaclass_usage(subclass_registry_metaclass, assert_correct_class_creation):
22
    class ParentClass(metaclass=subclass_registry_metaclass):
23
        pass
24
25
    assert_correct_class_creation(ParentClass)
26
27
28
@pytest.fixture
29
def usage_with_subclass(subclass_registry_metaclass):
30
    def parent_n_child_classes():
31
        class ParentClass(metaclass=subclass_registry_metaclass):
32
            pass
33
        @ParentClass.register_as_subclass('child1')
34
        class Child1(ParentClass):
35
            pass
36
37
        child1_instance1 = ParentClass.create('child1')
38
39
        assert ParentClass.subclasses['child1'] == Child1
40
        assert type(child1_instance1) == Child1
41
        assert isinstance(child1_instance1, Child1)
42
        assert isinstance(child1_instance1, ParentClass)
43
44
        return child1_instance1, Child1, ParentClass
45
    return parent_n_child_classes
46
47
48
@pytest.fixture
49
def plain_usage(subclass_registry_metaclass):
50
    def parent_n_child_classes():
51
        class ParentClass2(metaclass=subclass_registry_metaclass):
52
            pass
53
54
        @ParentClass2.register_as_subclass('child2')
55
        class Child2:
56
            pass
57
58
        child1_instance2 = ParentClass2.create('child2')
59
60
        assert ParentClass2.subclasses['child2'] == Child2
61
        assert type(child1_instance2) == Child2
62
        assert isinstance(child1_instance2, Child2)
63
        assert not isinstance(child1_instance2, ParentClass2)
64
        return child1_instance2, Child2, ParentClass2
65
    return parent_n_child_classes
66
67
68
def test_subclass_registry(usage_with_subclass, plain_usage):
69
    child1_instance1, Child1, ParentClass = usage_with_subclass()
70
71
    non_existent_identifier = 'child2'
72
73
    exception_message_regex = \
74
        f'Bad "{str(ParentClass.__name__)}" subclass request; requested subclass with identifier ' \
75
        f'{non_existent_identifier}, but known identifiers are ' \
76
        rf'\[{", ".join(subclass_identifier for subclass_identifier in ParentClass.subclasses.keys())}\]'
77
78
    with pytest.raises(ValueError, match=exception_message_regex):
79
        ParentClass.create(non_existent_identifier)
80
81
    child1_instance2, Child2, ParentClass2 = plain_usage()
82
    assert ParentClass.subclasses['child1'] == Child1
83