from pymoq.all import *Following the end-to-end tutorial for nbdev.
Project homepage: github
Full documentation: documentation
pip install moqpyThe package on pypi is called mockpy because pymoq was already taken
:(
Suppose we have the following setup in a python backend.
from typing import Protocol
class IWeb(Protocol):
"Interface for accessing internet resources"
def get(self, url:str, page:int, verbose:bool=False) -> str:
"Fetches the ressource at `url` and returns it in string representation"class RessourceFetcher:
base_url: str = "https://some_base.com/"
def __init__(self, web: IWeb):
self._web = web
def check_ressource(self, ressource_name: str, page:int, verbose:bool=False) -> bool:
url = self.base_url + ressource_name
ressource = self._web.get(url, page, verbose)
return ressource is not NoneWe want to test the fetch_ressource method of RessourceFetcher. More
specifically, we want to test that if the ressource is correctly
returned from the source, this method should return True, otherwise
False.
mock = Mock(IWeb)
mock.get\
.setup('https://some_base.com/ressource', int, False)\
.returns(True)
fetcher = RessourceFetcher(mock)If the call matches the siganture defined in the setup method, the
lambda in returns is called and its return value is returned:
assert fetcher.check_ressource('ressource', 1)If any part of the signature does not match, None is returned:
assert not fetcher.check_ressource('other_ressource', 1) # wrong ressource name
assert not fetcher.check_ressource('ressource', "1") # wrong type of page argument
assert not fetcher.check_ressource('ressource', "1", verbose=True) # wrong value for verbose argumentOne might want to check how often a function mock was invoked with a
specific call signature. This can easily be done via the .verify
method:
mock = Mock(IWeb)
fetcher = RessourceFetcher(mock)
# setup
mock.get.setup(str, int, bool).returns(True)
# act
fetcher.check_ressource('ressource', 1)
fetcher.check_ressource('ressource', 2)
fetcher.check_ressource('ressource', 1, verbose=True)
# assert
mock.get.verify(str, int, bool).times(3)
mock.get.verify(str, int, bool).more_than(1)
mock.get.verify(str, int, bool).more_than_or_equal_to(3)
mock.get.verify(str, int, bool).less_than(4)
mock.get.verify(str, int, bool).less_than_or_equal_to(3)
mock.get.verify(str, str).never()
mock.get.verify(str, AnyInt('page', 2).less_than(2), bool).times(2)mock = Mock(IWeb)
mock.get.setup('resource', int, bool).returns_sequence([1,2,3])
assert mock.get('resource', 1, True)==1
assert mock.get('resource', 2, False)==2
assert mock.get('resource', 3, True)==3
print(mock.get('ressource', 1, True))None
class WebException(Exception):
"""Exception that describes web-access errors"""mock = Mock(IWeb)
fetcher = RessourceFetcher(mock)
# setup failing web call
mock.get.setup('https://some_base.com/unavailable_ressource', int, bool).throws(WebException())
# act and assert exception
with pytest.raises(WebException):
fetcher.check_ressource('unavailable_ressource', 1, True)
# does not raise exception if call signature does not match
fetcher.check_ressource('available_ressource', 1, True);Refer to General Structure for more detail.