expecting

Elegant assertions library.

This is currently a work in progress.

• expecting.dict: Dictionary assertions, combined with other assertions makes it easier to verify complex dictionary schemas.
• expecting.list: Utility assertions, like order agnostic comparisons.
• expecting.number: Simple number comparisons, the small building blocks for more complex structured data checking.
• expecting.string: A variety of formats like date and time, URL, UUID.

Installation options

pip install expecting

poetry add expecting --group dev

Usage

Expecting consists of a set of assertion objects that can be used with assert statements in a clear, readable way. Most common assertion will be covered under a structured set of modules, following an intuitive naming schema:

import expecting

assert '2023-10-11' == expecting.string.datetime.iso8601_day()

Here, the expcting.string.datetime module introduces a handful of factory methods for asserting that the value is a string representing a date and time format.

It's specially useful with pytest and its amazing error messages, where an assertion failure message would look something like:

string/test_datetime.py:7 (test_iso8601_full_matches[2023/10/11 13:01:10])
'2023/10/11 13:01:10' != ~= <datetime as "%Y-%m-%dT%H:%M:%S.%f%z">

Expected :~= <datetime as "%Y-%m-%dT%H:%M:%S.%f%z">
Actual   :'2023/10/11 13:01:10'
<Click to see difference>

datetime_str = '2023/10/11 13:01:10'

    @pytest.mark.parametrize(
        'datetime_str',
        (
            '2023/10/11 13:01:10',
        )
    )
    def test_iso8601_full_matches(datetime_str: str):
>       assert datetime_str == expecting.string.datetime.iso8601_full()
E       assert '2023/10/11 13:01:10' == ~= <datetime as "%Y-%m-%dT%H:%M:%S.%f%z">
...

The ~= symbol prefixing the expected value is used denote this value is an "expecting object".

Contributing

Feel free to create issues or merge requests with any improvement or fix you might find useful.

API reference

• expecting.dict
  • containing
• expecting.list
  • containing
  • unordered
• expecting.number
  • expecting.number.ge
  • expecting.number.le
  • expecting.number.gt
  • expecting.number.lt
  • expecting.number.eq
  • expecting.number.ne
• expecting.string
  • expecting.string.datetime
    • expecting.string.datetime.iso8601_full
    • expecting.string.datetime.iso8601_millisecond
    • expecting.string.datetime.iso8601_second
    • expecting.string.datetime.iso8601_minute
    • expecting.string.datetime.iso8601_hour
    • expecting.string.datetime.iso8601_day
    • expecting.string.datetime.iso8601_month
    • expecting.string.datetime.iso8601_year
  • expecting.string.uuid
    • expecting.string.uuid.v1
    • expecting.string.uuid.v3
    • expecting.string.uuid.v4
    • expecting.string.uuid.v5
    • expecting.string.uuid.hex

expecting.dict

expecting.dict.containing

Asserts that a dictionary contains a sub-dictionary. Can

import expecting

current = {
    'color': 'yellow',
    'positions': [(1, 1), (2, 3), (4, 2)],
}
assert current == expecting.dict.containing({
    'positions': expecting.list.containing([(2, 3)]),
    'color': 'yellow',
})

expecting.list

expecting.list.containing

Asserts that a list contains a sub-list. Order is important.

import expecting

current = [1, 2, 3]
assert current == expecting.list.containing([2, 3])

expecting.list.unordered

Asserts that a list contains all the values, disregarding their order.

import expecting

current = [1, 2, 3]

assert current == expecting.list.unordered([3, 1, 2])

expecting.number

Disclaimer: of course writing assert a >= 1 is much easier and should be the preferred way to.

The functions under this namespace are intended for combined usage with other expecting objects for complex schema validations.

expecting.number.ge

Asserts number is greater than or equal to (>=) given value.

import expecting

assert 10 == expecting.number.ge(10)

expecting.number.le

Asserts number is lesser than or equal to (<=) given value.

import expecting

assert 10 == expecting.number.le(10)

expecting.number.gt

Asserts number is greater than (>) given value.

import expecting

assert 10 == expecting.number.gt(9)

expecting.number.lt

Asserts number is lesser than (<) given value.

import expecting

assert 10 == expecting.number.lt(11)

expecting.number.eq

Asserts number is equals to given value.

import expecting

assert 10 == expecting.number.eq(10)

expecting.number.ne

Asserts number is not equals to given value.

import expecting

assert 10 == expecting.number.ne(9)

expecting.string

expecting.string.datetime

expecting.string.datetime.iso8601_full

Asserts string is a valid ISO8601 full format, considering the timezone Z or UTC offset versions.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%dT%H:%M:%S.%f+000000.000000') == expecting.string.datetime.iso8601_full()
assert datetime.now().strftime('%Y-%m-%dT%H:%M:%S.%fZ') == expecting.string.datetime.iso8601_full()

expecting.string.datetime.iso8601_millisecond

Asserts string is a valid ISO8601 format up to the milliseconds.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%dT%H:%M:%S.%f') == expecting.string.datetime.iso8601_millisecond()

expecting.string.datetime.iso8601_second

Asserts string is a valid ISO8601 format up to the seconds

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%dT%H:%M:%S') == expecting.string.datetime.iso8601_second()

expecting.string.datetime.iso8601_minute

Asserts string is a valid ISO8601 format up to the minutes.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%dT%H:%M') == expecting.string.datetime.iso8601_minute()

expecting.string.datetime.iso8601_hour

Asserts string is a valid ISO8601 format up to the hours.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%dT%H') == expecting.string.datetime.iso8601_hour()

expecting.string.datetime.iso8601_day

Asserts string is a valid ISO8601 format up to the day.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m-%d') == expecting.string.datetime.iso8601_day()

expecting.string.datetime.iso8601_month

Asserts string is a valid ISO8601 format up to the month.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y-%m') == expecting.string.datetime.iso8601_month()

expecting.string.datetime.iso8601_year

Asserts string is a valid ISO8601 format up to the Year.

from datetime import datetime
import expecting

assert datetime.now().strftime('%Y') == expecting.string.datetime.iso8601_year()

expecting.string.uuid

expecting.string.uuid.v1

Asserts that a string is a valid UUID v1 hex

import uuid
import expecting

assert str(uuid.uuid1()) == expecting.string.uuid.v1()

expecting.string.uuid.v3

Asserts that a string is a valid UUID v3 hex

import uuid
import expecting

assert str(uuid.uuid3(uuid.uuid1(), 'bogus')) == expecting.string.uuid.v3()

expecting.string.uuid.v4

Asserts that a string is a valid UUID v4 hex

import uuid
import expecting

assert str(uuid.uuid4()) == expecting.string.uuid.v4()

expecting.string.uuid.v5

Asserts that a string is a valid UUID v5 hex

import uuid
import expecting

assert str(uuid.uuid5(uuid.uuid1(), 'bogus')) == expecting.string.uuid.v5()

expecting.string.uuid.hex

Asserts that a string is a valid UUID hex, disregarding the version.

import uuid
import expecting

assert str(uuid.uuid1()) == expecting.string.uuid.hex()
assert str(uuid.uuid3(uuid.uuid1(), 'bogus')) == expecting.string.uuid.hex()
assert str(uuid.uuid4()) == expecting.string.uuid.hex()
assert str(uuid.uuid5(uuid.uuid1(), 'bogus')) == expecting.string.uuid.hex()