matchlib 0.1.0

A tool for partial comparison of (nested) data structures

matchlib

This package provides a handy way to partially compare python data structures (typically nested lists/dictionaries).

Usage

from matchlib import matches

user = {
    'id': 42,
    'name': 'John Doe',
    'email': '[e-mail]',
    'posts': [
        {
            'id': 1,
            'text': 'some text'
        },
        {
            'id': 2,
            'text': 'lorem ipsum',
            'comments': [42, 142, 242]
        }
    ]
}

assert matches(
    user,
    {
        'id': ...,
        'name': 'John Doe',
        'email': '[e-mail]',
        ...: ...
    }
)

Same can be achieved using standard == operator with matchlib.Partial object:

from matchlib import Partial

assert user == Partial({
    'id': 42,
    ...: ...
})

assert list(range(10)) == Partial([0, 1, ..., 5, 6, 7, ...])

The ... "wildcard" could be placed at any nested level. Let's say we only need to check that comment 142 is present is specific post:

assert user == Partial({
    'posts': [
        ...,
        {
            'id': 2,
            'comments': [..., 142, ...],
            ...: ...
        }
    ],
    ...: ...
})

Some more hacks

mathchlib provides a Regex object that allows to match an arbitrary string element (except if it is a dict key) against a regular expression. Also pytest.approx is supported for floating-point numbers comparison:

from pytest import approx
from matchlib import Regex, Partial

account = {
    'id': 1,
    'balance': 1007.62,
    'owner': {
        'email': '[e-mail]',
    }
}

assert account == Partial({
    'id': ...,
    'balance': approx(1000, 0.1),
    'owner': {
        'email': Regex(r'\w+@domain\.com')
    }
})

If for any reason you dislike Ellipsis literal (...) a matchlib.Any object can be used interchangeably.