Open File Mock
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
