by DonOfDen
Posted on 13 Feb 2020
Tags: Python unittest exclude coverage
“Testing”, in general programming terms, is the practice of writing code (separate from your actual application code) that invokes the code it tests to help determine if there are any errors. It does not prove that code is correct (which is only possible under very restricted circumstances). It merely reports if the conditions the tester thought of are handled correctly.
In this blog we discuss few methods used to handle/cover input(), print() functions.
from nose.tools import *
from unittest import mock
from unittest.mock import patch
import io
def foo():
print("Something")
# Solution one: testing print with @patch
@patch('sys.stdout', new_callable=io.StringIO)
def test_foo_one(mock_stdout):
foo()
assert mock_stdout.getvalue() == 'Something\n'
# Solution two: testing print with with-statement
def test_foo_two():
with mock.patch('sys.stdout', new=io.StringIO()) as fake_stdout:
foo()
assert fake_stdout.getvalue() == 'Something\n'
# Solution three: testing print with with-statement
# and assert_has_calls
def test_foo_three():
with mock.patch('sys.stdout') as fake_stdout:
foo()
fake_stdout.assert_has_calls([
mock.call.write('Something'),
mock.call.write('\n')
])
from nose.tools import *
from unittest import mock
def bar():
ans = input("enter yes or no")
if ans == "yes":
return "you entered yes"
if ans == "no":
return "you entered no"
def test_bar_yes():
original_input = mock.builtins.input
mock.builtins.input = lambda _: "yes"
assert_equal(bar(), "you entered yes")
mock.builtins.input = original_input
def test_bar_no():
original_input = mock.builtins.input
mock.builtins.input = lambda _: "no"
assert_equal(bar(), "you entered no")
mock.builtins.input = original_input
Interesting one.. Python Mocking 101: Fake It Before You Make It
What is the purpose of mock objects?
Python mocking raw input in unittests
Unit Testing for user input and expected output in Python
How to Mock a user input in Python
Python Mocks: a gentle introduction
Python unit test for nested if statement
How to unit test an if-else statement in C# using just a stubclass?
Using unittest.mock to patch input() in Python 3
Mock Python’s built in print function
if __name__ == '__main__' from the coverage report , of course you can do that only if you already have a test case for your main() function in your tests.
As for why I choose to exclude rather than writing a new test case for the whole script is because if as I stated you already have a test case for your main() function the fact that you add an other test case for the script (just for having a 100 % coverage) will be just a duplicated one.
def main():
pass
if __name__ == "__main__":
main()
For how to exclude the if __name__ == '__main__' you can write a coverage configuration file and add in the section report:
[report]
exclude_lines =
if __name__ == .__main__.:
The default name for configuration files is .coveragerc, in the same directory coverage.py is being run in.
More info about the coverage configuration file can be found here
Please refer Galactic one of my project where I learnt how to implement the above.
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