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https://github.com/qweeze/matchlib

A tool for partial comparison of (nested) data structures
https://github.com/qweeze/matchlib

fuzzy-data-matching partial-comparison python-tests

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A tool for partial comparison of (nested) data structures

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## matchlib

[![PyPI version](https://badge.fury.io/py/matchlib.svg)](https://badge.fury.io/py/matchlib)

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

### Installation
```bash
pip install matchlib
```
### Usage
```python
from matchlib import matches

user = {
'id': 42,
'name': 'John Doe',
'email': 'johndoe@gmail.com',
'posts': [
{
'id': 1,
'text': 'some text'
},
{
'id': 2,
'text': 'lorem ipsum',
'comments': [42, 142, 242]
}
]
}

assert matches(
user,
{
'id': ...,
'name': 'John Doe',
'email': 'johndoe@gmail.com',
...: ...
}
)
```
Same can be achieved using standard `==` operator with `matchlib.Partial` object:
```python
from matchlib import Partial

assert user == Partial({
'id': 42,
'email': 'johndoe@gmail.com',
...: ...
})
```
The `...` "wildcard" could be placed at any nested level.
Let's say we only need to check that comment `142` is present in specific post:
```python
assert user == Partial({
'posts': [
...,
{
'id': 2,
'comments': [..., 142, ...],
...: ...
}
],
...: ...
})
```
Matching rules are simple:
- In __lists__ and __tuples__ `...` matches zero or more elements and order is preserved:
```python
Partial([1, 2, ...]) == [1, 2, 3, 4]
Partial([1, 2, ...]) == [1, 2]

Partial([1, 2, ...]) != [0, 1, 2]
Partial([1, 2, ...]) != [2, 1]
```
- Same for the __sets__ except they are unordered:
```python
Partial({1, 2, ...}) == {1, 2}
Partial({1, 2, ...}) == {0, 1, 2, 3}

Partial({1, 2, ...}) != {0, 1, 3}
```
- As __dict value__ `...` matches any object:
```python
Partial({'a': 1, 'b': ...}) == {'a': 1, 'b': 2}
```
- As __dict key__ `...` matches any key if assosiated values match:
```python
Partial({'a': 1, ...: 2}) == {'a': 2, 'b': 2}
```
- When passed as __both key and value__ matches zero or more arbitrary key-value pairs:
```python
Partial({'a': 1, ...: ...}) == {'a': 1, 'b': 2, 'c': 3}
```

### 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:
```python
from pytest import approx
from matchlib import Regex, Partial

account = {
'id': 1,
'balance': 1007.62,
'owner': {
'email': 'user42@domain.com',
}
}

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.