merge monkeypatch.replace into monkeypatch.setattr, also support monkeypatch.delattr.
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holger krekel
parent
da7133d201
commit
39503932a4
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@ -17,10 +17,10 @@ Changes between 2.3.5 and 2.4.DEV
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- PR27: correctly handle nose.SkipTest during collection. Thanks
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Antonio Cuni, Ronny Pfannschmidt.
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- new monkeypatch.replace() to avoid imports and provide a shorter
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- new monkeypatch.setattr() variant to provide a shorter
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invocation for patching out classes/functions from modules:
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monkeypatch.replace("requests.get", myfunc
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monkeypatch.setattr("requests.get", myfunc)
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will replace the "get" function of the "requests" module with ``myfunc``.
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@ -25,6 +25,39 @@ def pytest_funcarg__monkeypatch(request):
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request.addfinalizer(mpatch.undo)
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return mpatch
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def derive_importpath(import_path):
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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 attr, obj
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notset = object()
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class monkeypatch:
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@ -34,70 +67,66 @@ class monkeypatch:
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self._setitem = []
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self._cwd = None
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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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def setattr(self, target, name, value=notset, raising=True):
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""" set attribute value on target, memorizing the old value.
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By default raise AttributeError if the attribute did not exist.
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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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For convenience you can specify a string as ``target`` which
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will be interpreted as a dotted import path, with the last part
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being the attribute name. Example:
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``monkeypatch.setattr("os.getcwd", lambda x: "/")``
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would set the ``getcwd`` function of the ``os`` module.
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The ``raising`` value determines if the setattr should fail
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if the attribute is not already present (defaults to True
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which means it will raise).
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"""
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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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__tracebackhide__ = True
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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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raise AttributeEror if the attribute did not exist.
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if value is notset:
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if not isinstance(target, str):
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raise TypeError("use setattr(target, name, value) or "
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"setattr(target, value) with target being a dotted "
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"import string")
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value = name
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name, target = derive_importpath(target)
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"""
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oldval = getattr(obj, name, notset)
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oldval = getattr(target, name, notset)
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if raising and oldval is notset:
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raise AttributeError("%r has no attribute %r" %(obj, name))
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raise AttributeError("%r has no attribute %r" %(target, name))
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# avoid class descriptors like staticmethod/classmethod
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if inspect.isclass(obj):
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oldval = obj.__dict__.get(name, notset)
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self._setattr.insert(0, (obj, name, oldval))
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setattr(obj, name, value)
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if inspect.isclass(target):
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oldval = target.__dict__.get(name, notset)
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self._setattr.insert(0, (target, name, oldval))
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setattr(target, name, value)
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def delattr(self, obj, name, raising=True):
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""" delete attribute ``name`` from ``obj``, by default raise
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AttributeError it the attribute did not previously exist. """
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if not hasattr(obj, name):
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def delattr(self, target, name=notset, raising=True):
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""" delete attribute ``name`` from ``target``, by default raise
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AttributeError it the attribute did not previously exist.
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If no ``name`` is specified and ``target`` is a string
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it will be interpreted as a dotted import path with the
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last part being the attribute name.
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If raising is set to false, the attribute is allowed to not
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pre-exist.
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"""
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__tracebackhide__ = True
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if name is notset:
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if not isinstance(target, str):
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raise TypeError("use delattr(target, name) or "
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"delattr(target) with target being a dotted "
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"import string")
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name, target = derive_importpath(target)
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if not hasattr(target, name):
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if raising:
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raise AttributeError(name)
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else:
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self._setattr.insert(0, (obj, name, getattr(obj, name, notset)))
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delattr(obj, name)
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self._setattr.insert(0, (target, name,
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getattr(target, name, notset)))
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delattr(target, name)
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def setitem(self, dic, name, value):
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""" set dictionary entry ``name`` to value. """
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@ -48,11 +48,28 @@ requests in all your tests, you can do::
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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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monkeypatch.delattr("requests.session.Session.request")
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This autouse fixture will be executed for each test function and it
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will delete the method ``request.session.Session.request``
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so that any attempts within tests to create http requests will fail.
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example: setting an attribute on some class
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------------------------------------------------------
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If you need to patch out ``os.getcwd()`` to return an artifical
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value::
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def test_some_interaction(monkeypatch):
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monkeypatch.setattr("os.getcwd", lambda: "/")
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which is equivalent to the long form::
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def test_some_interaction(monkeypatch):
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import os
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monkeypatch.setattr(os, "getcwd", lambda: "/")
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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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@ -35,26 +35,32 @@ 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 TestReplace:
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class TestSetattrWithImportPath:
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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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monkeypatch.setattr("os.path.abspath", lambda x: "hello2")
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assert os.path.abspath("123") == "hello2"
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def test_string_expression_class(self, monkeypatch):
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monkeypatch.replace("_pytest.config.Config", 42)
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monkeypatch.setattr("_pytest.config.Config", 42)
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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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pytest.raises(TypeError, lambda: monkeypatch.setattr(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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lambda: monkeypatch.setattr("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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lambda: monkeypatch.setattr("os.path.qweqwe", None))
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def test_delattr(self, monkeypatch):
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monkeypatch.delattr("os.path.abspath")
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assert not hasattr(os.path, "abspath")
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monkeypatch.undo()
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assert os.path.abspath
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def test_delattr():
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class A:
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@ -262,3 +268,5 @@ def test_issue156_undo_staticmethod(Sample):
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monkeypatch.undo()
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assert Sample.hello()
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