monkeypatch.replace() now only accepts a string. Improved error handling and
docs thanks to suggestions from flub, pelme, schmir, ronny.
This commit is contained in:
holger krekel
parent
407283ef81
commit
4b88d6d2d7
11
CHANGELOG
11
CHANGELOG
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@ -1,15 +1,12 @@
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Changes between 2.3.5 and 2.4.DEV
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-----------------------------------
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- new monkeypatch.replace() to allow for more direct patching::
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- new monkeypatch.replace() to avoid imports and provide a shorter
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invocation for patching out classes/functions from modules:
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monkeypatch.replace(os.path.abspath, lambda x: "mocked")
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monkeypatch.replace("requests.get", myfunc
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instead of: monkeypatch.setattr(os.path, "abspath", lambda x: "mocked")
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You can also avoid imports by specifying a python path string::
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monkeypatch.replace("requests.get", ...)
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will replace the "get" function of the "requests" module with ``myfunc``.
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- fix issue322: tearDownClass is not run if setUpClass failed. Thanks
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Mathieu Agopian for the initial fix. Also make all of pytest/nose finalizer
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@ -1,6 +1,7 @@
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""" monkeypatching and mocking functionality. """
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import os, sys, inspect
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import pytest
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def pytest_funcarg__monkeypatch(request):
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"""The returned ``monkeypatch`` funcarg provides these
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@ -26,47 +27,6 @@ def pytest_funcarg__monkeypatch(request):
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notset = object()
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if sys.version_info < (3,0):
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def derive_obj_and_name(obj):
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name = obj.__name__
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real_obj = getattr(obj, "im_self", None)
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if real_obj is None:
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real_obj = getattr(obj, "im_class", None)
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if real_obj is None:
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real_obj = sys.modules[obj.__module__]
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assert getattr(real_obj, name) == obj, \
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"could not derive object/name pair"
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return name, real_obj
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else:
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def derive_obj_and_name(obj):
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name = obj.__name__
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real_obj = getattr(obj, "__self__", None)
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if real_obj is None:
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current = sys.modules[obj.__module__]
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for name in obj.__qualname__.split("."):
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real_obj = current
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current = getattr(current, name)
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assert getattr(real_obj, name) == obj, \
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"could not derive object/name pair"
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return name, real_obj
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def derive_from_string(target):
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rest = []
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while target:
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try:
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obj = __import__(target, None, None, "__doc__")
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except ImportError:
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if "." not in target:
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raise
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target, name = target.rsplit(".", 1)
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rest.append(name)
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else:
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assert len(rest) >= 1
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while len(rest) != 1:
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obj = getattr(obj, rest.pop())
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return rest[0], obj
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class monkeypatch:
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""" object keeping a record of setattr/item/env/syspath changes. """
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def __init__(self):
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@ -74,22 +34,45 @@ class monkeypatch:
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self._setitem = []
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self._cwd = None
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def replace(self, target, value):
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""" derive monkeypatching location from ``target`` and call
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setattr(derived_obj, derived_name, value).
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def replace(self, import_path, value):
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""" replace the object specified by a dotted ``import_path``
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with the given ``value``.
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This function can usually derive monkeypatch locations
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for function, method or class targets. It also accepts
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a string which is taken as a python path which is then
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tried to be imported. For example the target "os.path.abspath"
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will lead to a call to setattr(os.path, "abspath", value)
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without the need to import "os.path" yourself.
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For example ``replace("os.path.abspath", value)`` will
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trigger an ``import os.path`` and a subsequent
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setattr(os.path, "abspath", value). Or to prevent
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the requests library from performing requests you can call
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``replace("requests.sessions.Session.request", None)``
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which will lead to an import of ``requests.sessions`` and a call
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to ``setattr(requests.sessions.Session, "request", None)``.
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"""
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if isinstance(target, str):
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name, obj = derive_from_string(target)
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else:
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name, obj = derive_obj_and_name(target)
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return self.setattr(obj, name, value)
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if not isinstance(import_path, str) or "." not in import_path:
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raise TypeError("must be absolute import path string, not %r" %
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(import_path,))
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rest = []
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target = import_path
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while target:
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try:
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obj = __import__(target, None, None, "__doc__")
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except ImportError:
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if "." not in target:
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__tracebackhide__ = True
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pytest.fail("could not import any sub part: %s" %
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import_path)
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target, name = target.rsplit(".", 1)
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rest.append(name)
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else:
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assert rest
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try:
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while len(rest) > 1:
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attr = rest.pop()
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obj = getattr(obj, attr)
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attr = rest[0]
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getattr(obj, attr)
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except AttributeError:
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__tracebackhide__ = True
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pytest.fail("object %r has no attribute %r" % (obj, attr))
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return self.setattr(obj, attr, value)
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def setattr(self, obj, name, value, raising=True):
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""" set attribute ``name`` on ``obj`` to ``value``, by default
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@ -29,7 +29,7 @@ patch this function before calling into a function which uses it::
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def test_mytest(monkeypatch):
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def mockreturn(path):
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return '/abc'
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monkeypatch.setattr(os.path., 'expanduser', mockreturn)
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monkeypatch.setattr(os.path, 'expanduser', mockreturn)
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x = getssh()
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assert x == '/abc/.ssh'
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@ -37,6 +37,23 @@ Here our test function monkeypatches ``os.path.expanduser`` and
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then calls into an function that calls it. After the test function
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finishes the ``os.path.expanduser`` modification will be undone.
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example: preventing "requests" from remote operations
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------------------------------------------------------
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If you want to prevent the "requests" library from performing http
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requests in all your tests, you can do::
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# content of conftest.py
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import pytest
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@pytest.fixture(autouse=True)
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def no_requests(monkeypatch):
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monkeypatch.replace("requests.session.Session.request", None)
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This autouse fixture will be executed for all test functions and it
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will replace the method ``request.session.Session.request`` with the
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value None so that any attempts to create http requests will fail.
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Method reference of the monkeypatch function argument
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-----------------------------------------------------
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@ -35,29 +35,7 @@ def test_setattr():
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monkeypatch.undo() # double-undo makes no modification
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assert A.x == 5
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class TestDerived:
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def f(self):
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pass
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def test_class_function(self, monkeypatch):
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monkeypatch.replace(TestDerived.f, lambda x: 42)
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assert TestDerived().f() == 42
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def test_instance_function(self, monkeypatch):
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t = TestDerived()
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monkeypatch.replace(t.f, lambda: 42)
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assert t.f() == 42
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def test_module_class(self, monkeypatch):
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class New:
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pass
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monkeypatch.replace(TestDerived, New)
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assert TestDerived == New
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def test_nested_module(self, monkeypatch):
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monkeypatch.replace(os.path.abspath, lambda x: "hello")
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assert os.path.abspath("123") == "hello"
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class TestReplace:
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def test_string_expression(self, monkeypatch):
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monkeypatch.replace("os.path.abspath", lambda x: "hello2")
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assert os.path.abspath("123") == "hello2"
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@ -67,6 +45,17 @@ class TestDerived:
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import _pytest
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assert _pytest.config.Config == 42
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def test_wrong_target(self, monkeypatch):
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pytest.raises(TypeError, lambda: monkeypatch.replace(None, None))
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def test_unknown_import(self, monkeypatch):
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pytest.raises(pytest.fail.Exception,
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lambda: monkeypatch.replace("unkn123.classx", None))
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def test_unknown_attr(self, monkeypatch):
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pytest.raises(pytest.fail.Exception,
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lambda: monkeypatch.replace("os.path.qweqwe", None))
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def test_delattr():
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class A:
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x = 1
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