I have 2 functions and the other one is called only when the parameter passed is True.
def func1(para1 = True):
// Some lines of code
if para1 == True:
func2()
def func2():
// Some lines of code
Now, I'm trying to create a unittest that checks whether the nested function func2 is being called(When parameter passed to func1 is true). I checked online and found something related to Mock() but did not understand how to use for this particular test case. How can I proceed with this?
example.py:
def func1(para1=True):
if para1 == True:
func2()
def func2():
pass
test_example.py:
from unittest import TestCase
import unittest
from unittest.mock import patch
from example import func1
class TestExample(TestCase):
#patch('example.func2')
def test_func1__should_call_func2(self, mock_func2):
func1()
mock_func2.assert_called_once()
#patch('example.func2')
def test_func1__should_not_call_func2(self, mock_func2):
func1(False)
mock_func2.assert_not_called()
if __name__ == '__main__':
unittest.main()
Test result:
..
----------------------------------------------------------------------
Ran 2 tests in 0.001s
OK
A brief version of my custom class, this class reads a .txt file and return an output accordingly.
class MyClass:
def some_method(self, arg1, arg2):
pass
I need to give the solution in this form, this is my main.py file
def main():
input_file = sys.argv[1]
# parse the file and process the command
# print the output
if __name__ == "__main__":
main()
I need to read the file from sys.argv[1].
CLI should work like this:
python -m main <absolute_path_to_input_file>
I am not able to figure out how should I approach this?
I've written some python code that needs to read a config file at /etc/myapp/config.conf . I want to write a unit test for what happens if that file isn't there, or contains bad values, the usual stuff. Lets say it looks like this...
""" myapp.py
"""
def readconf()
""" Returns string of values read from file
"""
s = ''
with open('/etc/myapp/config.conf', 'r') as f:
s = f.read()
return s
And then I have other code that parses s for its values.
Can I, through some magic Python functionality, make any calls that readconf makes to open redirect to custom locations that I set as part of my test environment?
Example would be:
main.py
def _open_file(path):
with open(path, 'r') as f:
return f.read()
def foo():
return _open_file("/sys/conf")
test.py
from unittest.mock import patch
from main import foo
def test_when_file_not_found():
with patch('main._open_file') as mopen_file:
# Setup mock to raise the error u want
mopen_file.side_effect = FileNotFoundError()
# Run actual function
result = foo()
# Assert if result is expected
assert result == "Sorry, missing file"
Instead of hard-coding the config file, you can externalize it or parameterize it. There are 2 ways to do it:
Environment variables: Use a $CONFIG environment variable that contains the location of the config file. You can run the test with an environment variable that can be set using os.environ['CONFIG'].
CLI params: Initialize the module with commandline params. For tests, you can set sys.argv and let the config property be set by that.
In order to mock just calls to open in your function, while not replacing the call with a helper function, as in Nf4r's answer, you can use a custom patch context manager:
from contextlib import contextmanager
from types import CodeType
#contextmanager
def patch_call(func, call, replacement):
fn_code = func.__code__
try:
func.__code__ = CodeType(
fn_code.co_argcount,
fn_code.co_kwonlyargcount,
fn_code.co_nlocals,
fn_code.co_stacksize,
fn_code.co_flags,
fn_code.co_code,
fn_code.co_consts,
tuple(
replacement if call == name else name
for name in fn_code.co_names
),
fn_code.co_varnames,
fn_code.co_filename,
fn_code.co_name,
fn_code.co_firstlineno,
fn_code.co_lnotab,
fn_code.co_freevars,
fn_code.co_cellvars,
)
yield
finally:
func.__code__ = fn_code
Now you can patch your function:
def patched_open(*args):
raise FileNotFoundError
with patch_call(readconf, "open", "patched_open"):
...
You can use mock to patch a module's instance of the 'open' built-in to redirect to a custom function.
""" myapp.py
"""
def readconf():
s = ''
with open('./config.conf', 'r') as f:
s = f.read()
return s
""" test_myapp.py
"""
import unittest
from unittest import mock
import myapp
def my_open(path, mode):
return open('asdf', mode)
class TestSystem(unittest.TestCase):
#mock.patch('myapp.open', my_open)
def test_config_not_found(self):
try:
result = myapp.readconf()
assert(False)
except FileNotFoundError as e:
assert(True)
if __name__ == '__main__':
unittest.main()
You could also do it with a lambda like this, if you wanted to avoid declaring another function.
#mock.patch('myapp.open', lambda path, mode: open('asdf', mode))
def test_config_not_found(self):
...
I have the following python file board.py:
def __init__(self, language):
self.foo = Foo(language)
self.words = Aux(self.foo)
And I'm creating this test_file:
#classmethod
def setUpClass(cls):
super().setUpClass()
cls.board = Board('pt')
def test_total_time(self):
self.board.total_time(True)
#some assert
But I'm getting a FileNotFoundError because Aux.___init____() calls a self.foo.method() that opens a file and reads from it.
Is there a way to mock self.foo.method(), or the class Aux?
You will want to patch the module. If you give me the name of the test file and the class you are testing. I can finish this answer for you.
In the test file:
import unittest
def BoardTestCase(unittest.TestCase):
#classmethod
def setUpClass(cls):
super().setUpClass()
cls.aux_mock = unittest.mock.patch('file_undertest.Aux')
cls.board = Board('pt')
def test_total_time(self):
self.board.total_time(True)
#some assert
I would suggest using pytest instead of the standard library unittest. Your tests will be written as functions meaning you can reuse the Board class only when needed to. You can set more robust fixtures (Board class test cases) and the mocker extension is more intuitive if you spend the 15 minutes to wrap your head around it.
I have the following class file and a corresponding test file
dir.py:
import os
class Dir:
def __init__(self, path=''):
self.path = path
#property
def path(self):
return self._path
#path.setter
def path(self, path):
abspath = os.path.abspath(path)
if abspath.exists():
self._path = path
else:
raise IOError(f'{path} does not exist')
and dir_test.py:
import unittest
from ..dir import Dir
class TestDir(unittest.TestCase):
def IOErrorIfPathNotExists(self):
with self.assertRaises(IOError):
Dir.path = "~/invalidpath/"
with self.assertRaises(IOError):
Dir('~/invalidpath/')
if __name__ == "__main__":
unittest.main()
but when I run
pytest -x dir_test.py
it just prints no tests ran in 0.01 seconds
and I have no idea why. It is my first time using pytest except with exercises from exercism.io, and I can't spot any difference to their test files.
I am running it in a virtual environment (Python 3.6.5), with pytest and pytest-cache installed via pip.
That's because your test method is not named properly.
By default, pytest will consider any class prefixed with Test as a test collection.
Yours is TestDir, this matches.
By default, pytest will consider any function prefixed with test as a test.
Yours is IOErrorIfPathNotExists, which does not start with test and is not executed.
Source.