omlnaut/pymoq

https://omlnaut.github.io/pymoq/

pymoq

from pymoq.all import *

Following the end-to-end tutorial for nbdev.

Project homepage: github

Full documentation: documentation

Install

pip install moqpy

The package on pypi is called mockpy because pymoq was already taken :(

Quickstart

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 None

We 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.

Setting up the mock

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 argument

Verification

One 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)

Setup sequences

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

Setup exceptions

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);

Deep Dive

Refer to General Structure for more detail.

pymoq's Issues

Sidebar.yml regenerated on `nbdev_preview`

Description

Issue - sidebar.yml was being regenerated on every nbdev_preview execution.

This was resulting in custom changes made being overridden.
Here's an example:-

If I change the section implementation to Pascal case Implementation,
upon running nbdev_preview it automatically sets it to the directory name,
which is implementation. This is not an expected behavior.

Redundant files

Description

Issue :-

files like

• styles.css
• sidebar.yml
• implementation/_quarto.yml
• implementation/nbdev.yml
• implementation/nbdev.yml

are redundant as nbdev uses these files only from the root of nbs directory.

Fixed port for preview

Description

Issue - A random port was used for preview

Nested documentations under Implementation section

Description

auto: "/*.ipynb” was not working, and section: Implementation

contents: implementation/*

was also raising an error.

Solution:-

After the fix, the preview looks like this

solution source - Thanks @seeM