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Description:

openmockfile 1.0.2

Description
This library contains object, which can be used during mocking files in
tests. Features:

You can register different actions (provide different objects) for
different paths
You can add text, which will be returned on read
You can select behavior for paths, which are not registered.
Supported behaviors:

Raise FileNotFoundError exception (default behavior)
Return original file from filesystem
Return mock object

Install
It can be installed with following command:
pip install open-mock-file

Usage:

Examples
Mock open first file with custom object, second one with string data and
raise FileNotFoundError for not registered path:
from unittest.mock import patch
from open_file_mock import MockOpen

class FileObject:
def __init__(self, data):
self.data = data

def read(self, *args, **kwargs):
return self.data

def write(self, data, *args, **kwargs):
self.data = data

def __enter__(self):
return self

def __exit__(self, exc_type, exc_val, exc_tb):
pass

with patch('builtins.open', new_callable=MockOpen) as open_mock:
open_mock.register_object_for_path(path='/tmp/f1', obj=FileObject('Some data'))
open_mock.set_read_data_for(path='/tmp/f2', data='file2 data')
with open('/tmp/f1') as f1:
print(f1.read())
f1.write('Other data')
print(f1.read())
print('----------------------')

with open('/tmp/f2') as f2:
print(f2.read())
print('----------------------')

open('/etc/hostname')
output:
Some data
Other data
----------------------
file2 data
----------------------
Traceback (most recent call last):
...
FileNotFoundError: File /etc/hostname not found in mock function
Set default behavior (for not registered paths) to return original file:
from unittest.mock import patch, MagicMock
from open_file_mock import MockOpen, DEFAULTS_ORIGINAL

with patch('builtins.open', new_callable=MockOpen) as open_mock:
open_mock.default_behavior = DEFAULTS_ORIGINAL
open_mock.register_object_for_path(path='/tmp/f1', obj=MagicMock())
with open('/tmp/f1') as f1:
print(f1.read())
print('----------------------')

with open('/etc/hostname') as f2:
print(f2.read())
print('----------------------')
output:
<MagicMock name='mock.__enter__().read()' id='...'>
----------------------
myhost

----------------------
Set default behavior to return new mock:
from unittest.mock import patch
from open_file_mock import MockOpen, DEFAULTS_MOCK

with patch('builtins.open', new_callable=MockOpen) as open_mock:
open_mock.default_behavior = DEFAULTS_MOCK
open_mock.set_read_data_for('/tmp/f1', 'QWERTY')
with open('/tmp/f1') as f1:
print(f1.read())
print('----------------------')

with open('/etc/hostname') as f2:
print(f2.read())
print('----------------------')
output:
QWERTY
----------------------
<MagicMock name='mock.__enter__().read()' id='...'>
----------------------
Yoy can get registered object with get_object_for_path method:
from unittest.mock import patch
from open_file_mock import MockOpen

class FileObject:
def __init__(self, data):
self.data = data

def read(self, *args, **kwargs):
return self.data

def write(self, data, *args, **kwargs):
self.data = data

def __enter__(self):
return self

def __exit__(self, exc_type, exc_val, exc_tb):
pass

with patch('builtins.open', new_callable=MockOpen) as open_mock:
open_mock.register_object_for_path(path='/tmp/f1', obj=FileObject('Some data'))
open_mock.set_read_data_for(path='/tmp/f2', data='file2 data')
with open('/tmp/f1') as f1:
print(f1.read())
print('----------------------')

print(open_mock.get_object_for_path('/tmp/f1'))
output:
Some data
----------------------
<__main__.FileObject object at ...>

Object methods:

register_object_for_path(path, obj) - allow to register new
object for provided path. Can be used once for particular path
update_object_for_path(path, obj) - update registered path or
create new mapping if not exists
unregister_path(path) - remove path mapping
set_read_data_for(path, data) - set data which will be
returned of file read
get_object_for_path(path) - returns object registered for
path. If mapping not exists, raises KeyError