https://github.com/asottile/re-assert

show where your regex match assertion failed!
https://github.com/asottile/re-assert

Last synced: about 13 hours ago
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show where your regex match assertion failed!

• Host: GitHub
• URL: https://github.com/asottile/re-assert
• Owner: asottile
• License: mit
• Created: 2019-09-21T19:57:18.000Z (about 5 years ago)
• Default Branch: main
• Last Pushed: 2024-10-29T01:22:00.000Z (15 days ago)
• Last Synced: 2024-10-30T04:49:37.205Z (14 days ago)
• Language: Python
• Homepage:
• Size: 197 KB
• Stars: 81
• Watchers: 4
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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re-assert

=========

show where your regex match assertion failed!

## installation

```bash

pip install re-assert

```

## usage

`re-assert` provides a helper class to make assertions of regexes simpler.

### `re_assert.Matches(pattern: str, *args, **kwargs)`

construct a `Matches` object.

_note_: under the hood, `re-assert` uses the [`regex`] library for matching,

any `*args` / `**kwargs` that `regex.compile` supports will work.  in general,

 the `regex` library is 100% compatible with the `re` library (and will even

accept its flags, etc.)

[`regex`]: https://pypi.org/project/regex/

### `re_assert.Matches.from_pattern(pattern: Pattern[str]) -> Matches`

construct a `Matches` object from an already-compiled regex.

this is useful (for instance) if you're testing an existing compiled regex.

```pycon

>>> import re

>>> reg = re.compile('foo')

>>> Matches.from_pattern(reg) == 'fork'

False

>>> Matches.from_pattern(reg) == 'food'

True

```

### `Matches.__eq__(other)` (`==`)

the equality operator is overridden for use with assertion frameworks such

as pytest

```pycon

>>> pat = Matches('foo')

>>> pat == 'bar'

False

>>> pat == 'food'

True

```

### `Matches.__repr__()` (`repr(...)`)

a side-effect of an equality failure changes the `repr(...)` of a `Matches`

object.  this allows for useful pytest assertion messages:

```pytest

>       assert Matches('foo') == 'fork'

E       AssertionError: assert Matches('foo'...ork\n    #    ^ == 'fork'

E         -Matches('foo')\n

E         -    # regex failed to match at:\n

E         -    #\n

E         -    #> fork\n

E         -    #    ^

E         +'fork'

```

### `Matches.assert_matches(s: str)`

if you're using some other test framework, this method is useful for producing

a readable traceback

```pycon

>>> Matches('foo').assert_matches('food')

>>> Matches('foo').assert_matches('fork')

Traceback (most recent call last):

  File "", line 1, in 

  File "/home/asottile/workspace/re-assert/re_assert.py", line 63, in assert_matches

    assert self == s, self._fail

AssertionError:  regex failed to match at:

> fork

    ^

```