1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
# Copyright 2008 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# This is a fork of the pymox library intended to work with Python 3.
# The file was modified by quermit@gmail.com and dawid.fatyga@gmail.com
import inspect
class StubOutForTesting(object):
"""Sample Usage:
You want os.path.exists() to always return true during testing.
stubs = StubOutForTesting()
stubs.Set(os.path, 'exists', lambda x: 1)
...
stubs.UnsetAll()
The above changes os.path.exists into a lambda that returns 1. Once
the ... part of the code finishes, the UnsetAll() looks up the old value
of os.path.exists and restores it.
"""
def __init__(self):
self.cache = []
self.stubs = []
def __del__(self):
self.SmartUnsetAll()
self.UnsetAll()
def SmartSet(self, obj, attr_name, new_attr):
"""Replace obj.attr_name with new_attr.
This method is smart and works at the module, class, and instance level
while preserving proper inheritance. It will not stub out C types
however unless that has been explicitly allowed by the type.
This method supports the case where attr_name is a staticmethod or a
classmethod of obj.
Notes:
- If obj is an instance, then it is its class that will actually be
stubbed. Note that the method Set() does not do that: if obj is
an instance, it (and not its class) will be stubbed.
- The stubbing is using the builtin getattr and setattr. So, the
__get__ and __set__ will be called when stubbing (TODO: A better
idea would probably be to manipulate obj.__dict__ instead of
getattr() and setattr()).
Raises AttributeError if the attribute cannot be found.
"""
if (inspect.ismodule(obj) or
(not inspect.isclass(obj) and attr_name in obj.__dict__)):
orig_obj = obj
orig_attr = getattr(obj, attr_name)
else:
if not inspect.isclass(obj):
mro = list(inspect.getmro(obj.__class__))
else:
mro = list(inspect.getmro(obj))
mro.reverse()
orig_attr = None
for cls in mro:
try:
orig_obj = cls
orig_attr = getattr(obj, attr_name)
except AttributeError:
continue
if orig_attr is None:
raise AttributeError("Attribute not found.")
# Calling getattr() on a staticmethod transforms it to a 'normal'
# function. We need to ensure that we put it back as a staticmethod.
old_attribute = obj.__dict__.get(attr_name)
if (old_attribute is not None
and isinstance(old_attribute, staticmethod)):
orig_attr = staticmethod(orig_attr)
self.stubs.append((orig_obj, attr_name, orig_attr))
setattr(orig_obj, attr_name, new_attr)
def SmartUnsetAll(self):
"""Reverses all the SmartSet() calls.
Restores things to their original definition. Its okay to call
SmartUnsetAll() repeatedly, as later calls have no effect if no
SmartSet() calls have been made.
"""
self.stubs.reverse()
for args in self.stubs:
setattr(*args)
self.stubs = []
def Set(self, parent, child_name, new_child):
"""Replace child_name's old definition with new_child.
Replace definiion in the context of the given parent. The parent could
be a module when the child is a function at module scope. Or the parent
could be a class when a class' method is being replaced. The named
child is set to new_child, while the prior definition is saved away
for later, when UnsetAll() is called.
This method supports the case where child_name is a staticmethod or a
classmethod of parent.
"""
old_child = getattr(parent, child_name)
old_attribute = parent.__dict__.get(child_name)
if old_attribute is not None:
if isinstance(old_attribute, staticmethod):
old_child = staticmethod(old_child)
elif isinstance(old_attribute, classmethod):
old_child = classmethod(old_child.__func__)
self.cache.append((parent, old_child, child_name))
setattr(parent, child_name, new_child)
def UnsetAll(self):
"""Reverses all the Set() calls.
Restores things to their original definition. Its okay to call
UnsetAll() repeatedly, as later calls have no effect if no Set()
calls have been made.
"""
# Undo calls to Set() in reverse order, in case Set() was called on the
# same arguments repeatedly (want the original call to be last one
# undone)
self.cache.reverse()
for (parent, old_child, child_name) in self.cache:
setattr(parent, child_name, old_child)
self.cache = []
|
