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import pytest |
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@pytest.fixture |
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def dummy_handle(): |
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def handle(self, *args, **kwargs): |
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return f'{type(self).__name__} handle request with args [{", ".join((str(_) for _ in args))}] and kwargs [{", ".join(f"{k}={v}" for k, v in kwargs.items())}]' |
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return handle |
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def test_proxy_behaviour(dummy_handle, capsys): |
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from typing import List |
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from software_patterns import Proxy |
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# replicate client code that wants to use the proxy pattern |
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class ClientSubject(object): |
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""" "A class with a request instance method.""" |
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def request(self, *args, **kwargs): |
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print(dummy_handle(self, *args, **kwargs)) |
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return type(self).__name__ |
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# Derive from Proxy |
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class ClientProxy(Proxy): |
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def request(self, *args, **kwargs): |
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# run proxy code before sending request to the "proxied" handler |
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before_args = list(['before'] + list(args)) |
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print(dummy_handle(self, *before_args, **kwargs)) |
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# handle request with the proxied logic |
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# _ = super().request(*args, **kwargs) |
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_ = self._proxy_subject.request(*args, **kwargs) |
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assert _ == 'ClientSubject' |
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# run proxy code after request to the "proxied" handler |
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after_args = list(['after'] + list(args)) |
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print(dummy_handle(self, *after_args, **kwargs)) |
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return _ |
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real_subject = ClientSubject() |
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proxy = ClientProxy(real_subject) |
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# use proxy in a scenario |
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# First test what happens without using proxy |
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args: List = [1, 2] |
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kwargs = {'k1': 'v1'} |
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result = real_subject.request(*args, **kwargs) |
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captured = capsys.readouterr() |
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assert captured.out == dummy_handle(real_subject, 1, 2, k1='v1') + '\n' |
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assert ( |
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captured.out |
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== f'ClientSubject handle request with args [{", ".join(str(_) for _ in args)}] and kwargs [{", ".join(f"{k}={v}" for k, v in kwargs.items())}]\n' |
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) |
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assert result == type(real_subject).__name__ |
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assert result == 'ClientSubject' |
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# Now test what happens using proxy |
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result = proxy.request(*args, **kwargs) |
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captured = capsys.readouterr() |
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assert ( |
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captured.out |
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== dummy_handle(*list([proxy, 'before'] + args), **kwargs) |
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+ '\n' |
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+ dummy_handle(*list([real_subject] + args), **kwargs) |
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+ '\n' |
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+ dummy_handle(*list([proxy, 'after'] + args), **kwargs) |
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+ '\n' |
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) |
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assert ( |
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captured.out |
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== f'ClientProxy handle request with args [{", ".join(str(_) for _ in ["before"] + args)}] and kwargs [{", ".join(f"{k}={v}" for k, v in kwargs.items())}]\n' |
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+ f'ClientSubject handle request with args [{", ".join(str(_) for _ in args)}] and kwargs [{", ".join(f"{k}={v}" for k, v in kwargs.items())}]\n' |
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+ f'ClientProxy handle request with args [{", ".join(str(_) for _ in ["after"] + args)}] and kwargs [{", ".join(f"{k}={v}" for k, v in kwargs.items())}]\n' |
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) |
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assert result == type(real_subject).__name__ |
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assert result == 'ClientSubject' |
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85
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View Code Duplication |
def test_simple_proxy(): |
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86
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from typing import Callable |
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from software_patterns import Proxy |
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RemoteCall = Callable[[int], int] |
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remote_call: RemoteCall = lambda x: x + 1 |
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# Code that the developer writes |
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VALUE = 10 |
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class ClientProxy(Proxy[RemoteCall]): |
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def __call__(self, x: int): |
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return self._proxy_subject(x + VALUE) |
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proxy: ClientProxy = ClientProxy(remote_call) |
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assert remote_call(2) == 2 + 1 |
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assert proxy(2) == 2 + VALUE + 1 |
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105
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106
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View Code Duplication |
def test_proxy_as_instance(): |
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107
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from typing import Callable |
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108
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109
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from software_patterns import Proxy |
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111
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RemoteCall = Callable[[int], int] |
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113
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remote_call: RemoteCall = lambda x: x + 1 |
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115
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# Code that the developer writes |
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VALUE = 10 |
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118
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class ClientProxy(Proxy[RemoteCall]): |
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def __call__(self, x: int): |
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return self._proxy_subject(x + VALUE) |
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122
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proxy: ClientProxy = ClientProxy(remote_call) |
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assert remote_call(2) == 2 + 1 |
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assert proxy(2) == 2 + VALUE + 1 |
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assert hash(proxy) == hash(remote_call) |
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129
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130
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def test_mapping_proxy(): |
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from typing import Mapping |
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133
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from software_patterns import Proxy |
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135
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# test data |
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RemoteMapping = Mapping[str, str] |
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remote_mapping: RemoteMapping = { |
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'id_1': 'a', |
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'id_2': 'b', |
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} |
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143
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## Code that the developer writes |
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145
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class ClientProxy(Proxy[Mapping]): |
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CACHE = { |
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'id_1': 'a-cached', |
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} |
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150
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def __getitem__(self, str_id: str): |
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return self.CACHE.get(str_id, self._proxy_subject[str_id]) |
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153
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def __contains__(self, element): |
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return element in self._proxy_subject |
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156
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def wipe_cache(self): |
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self.CACHE = {} |
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159
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proxy: ClientProxy = ClientProxy(remote_mapping) |
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# Test code |
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assert remote_mapping['id_1'] == 'a' |
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assert remote_mapping['id_2'] == 'b' |
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assert 'id_1' in remote_mapping |
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166
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assert proxy['id_1'] == 'a-cached' |
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assert proxy['id_2'] == 'b' |
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assert 'id_1' in proxy |
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170
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# Proxy delegates attribute requests (ie 'keys' as below) to subject |
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assert sorted(remote_mapping.keys()) == sorted(proxy.keys()) |
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assert str(proxy) == str(remote_mapping) |
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proxy.wipe_cache() |
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assert proxy['id_1'] == 'a' |
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assert proxy['id_2'] == 'b' |
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assert sorted(remote_mapping.keys()) == sorted(proxy.keys()) |
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assert str(proxy) == str(remote_mapping) |
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boromir674 /
software-patterns
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