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# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
'''Helper metaclass do 'decorate' docstrings from base test case classes'''
import types
def copy_func(func):
'''Helper function to copy a function object (except docstring)'''
return types.FunctionType(func.func_code, func.func_globals, func.func_name,
func.func_defaults, func.func_closure)
class DocModifier(type):
'''Metaclass for modifiying method documentation.
It allows the managed class to modify the method documentation, adding
prefixes and suffixes to a given set of methods.
For example, you have some unittest.TestCases that run on different set
of data. These methods could be written once in a base class and the
inheriting class just setup different setUp/tearDown methods with the
proper data. To differentiate the methods when using docstrings, you
can add a suffix or prefix to the docstring.
Variables in the implementing class:
doc_prefix - The prefix to the docstring
doc_suffix - The suffix to the docstring
doc_filter - The function to filter the methods. If not provided, this
no docstrings are changed.'''
def __new__(mcs, name, bases, dct):
# FIXME currently we have to define doc_filter on each subclass
filter_function = dct.get('doc_filter')
if not filter_function:
filter_function = lambda x: False
for base in bases:
for attr in [x for x in base.__dict__ if filter_function(x)]:
original = getattr(base, attr)
if original.__doc__:
copy = copy_func(original)
copy.__doc__ = (dct.get('doc_prefix', '') +
original.__doc__ +
dct.get('doc_suffix', ''))
dct[attr] = copy
return type.__new__(mcs, name, bases, dct)
def __init__(mcs, name, bases, dct):
super(DocModifier, mcs).__init__(name, bases, dct)
if __name__ == '__main__':
# tests
class BaseTest(object):
__metaclass__ = DocModifier
def testBase(self):
'''base'''
def testWithoutDoc(self):
pass
class Implementing(BaseTest):
doc_filter = lambda x: x.startswith('test')
doc_prefix = 'prefix'
doc_suffix = 'suffix'
class OnlyPrefix(BaseTest):
doc_filter = lambda x: x.startswith('test')
doc_prefix = 'prefix'
class OnlySuffix(BaseTest):
doc_filter = lambda x: x.startswith('test')
doc_suffix = 'suffix'
assert (Implementing.testBase.__doc__ == 'prefixbasesuffix')
assert (Implementing.testWithoutDoc.__doc__ == None)
assert (OnlySuffix.testBase.__doc__ == 'basesuffix')
assert (OnlySuffix.testWithoutDoc.__doc__ == None)
assert (OnlyPrefix.testBase.__doc__ == 'prefixbase')
assert (OnlyPrefix.testWithoutDoc.__doc__ == None)
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