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https://github.com/ets-labs/python-dependency-injector.git
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67 lines
1.6 KiB
Python
67 lines
1.6 KiB
Python
"""Provider overriding example."""
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import sqlite3
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from objects.providers import Singleton
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from objects.providers import NewInstance
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from objects.injections import KwArg
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from objects.injections import Attribute
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class ObjectA(object):
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"""ObjectA has dependency on database."""
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def __init__(self, database):
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"""Initializer.
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Database dependency need to be injected via init arg."""
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self.database = database
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def get_one(self):
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"""Select one from database and return it."""
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return self.database.execute('SELECT 1')
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class ObjectAMock(ObjectA):
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"""Mock of ObjectA.
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Has no dependency on database.
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"""
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def __init__(self):
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"""Initializer."""
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def get_one(self):
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"""Select one from database and return it.
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Mock makes no database queries and always returns two instead of one.
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"""
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return 2
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# Database and `ObjectA` providers.
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database = Singleton(sqlite3.Connection,
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KwArg('database', ':memory:'),
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KwArg('timeout', 30),
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KwArg('detect_types', True),
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KwArg('isolation_level', 'EXCLUSIVE'),
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Attribute('row_factory', sqlite3.Row))
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object_a = NewInstance(ObjectA,
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KwArg('database', database))
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# Overriding `ObjectA` provider with `ObjectAMock` provider.
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object_a.override(NewInstance(ObjectAMock))
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# Creating several `ObjectA` instances.
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object_a_1 = object_a()
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object_a_2 = object_a()
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# Making some asserts.
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assert object_a_1 is not object_a_2
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assert object_a_1.get_one() == object_a_2.get_one() == 2
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