verify 0.4.0

A painless assertion library for Python.

Verify is a painless assertion library for Python.

Links

• Project: https://github.com/dgilland/verify

• Documentation: http://verify.readthedocs.org

• PyPI: https://pypi.python.org/pypi/verify/

• TravisCI: https://travis-ci.org/dgilland/verify

Quickstart

Install using pip:

pip install verify

Verify some value using multiple assertions:

from verify import expect, Not, Truthy, Falsy, Less, Greater

expect(5 * 5,
       Truthy(),
       Not(Falsy),
       Greater(15),
       Less(30))

Verify using your own assert functions:

def is_just_right(value):
    assert value != 'too cold' and value != 'too hot', 'Not just right!'

# Passes
expect(25, is_just_right)

# Fails
try:
    expect(31, is_just_right)
expect AssertionError:
    raise

Or your own predicate functions:

def is_awesome(value):
    return 'awesome' in value

def is_more_awesome(value):
    return value > 'awesome'

expect('so awesome', is_awesome, is_more_awesome)

But you don’t have to use expect since the verify assertions can be used on their own:

import verify

# These would pass.
verify.Truthy(1)
verify.Equal(2, 2)
verify.Greater(3, 2)

# These would fail with an AssertionError
verify.Truthy(0)
verify.Equal(2, 3)
verify.Greater(2, 3)

And if you’d prefer to see assert being used, all verify assertions will return True if no AssertionError is raised:

assert Truthy(1)
assert Expect(1, Truthy(), Number())

Validators

All of the validators in verify are callables that can be used in two contexts:

1. By themselves as in Equal(a, b) which will raise an AssertionError if false.

2. In combination with expect as in expect(a, Equal(b)) which could also raise an AssertionError.

The available validators are:

Validator	Description
Not	Assert that a callable doesn’t raise an AssertionError.
Predicate	Assert that predicate(a) (predicate() should return a boolean).
Equal	Assert that a == b.
Match	Assert that a matches regular expression b.
Greater	Assert that a > b.
GreaterEqual	Assert that a >= b.
Less	Assert that a < b.
LessEqual	Assert that a <= b.
Between	Assert that b <= a <= c.
Length	Assert that b <= len(a) <= c.
Is	Assert that a is b.
IsTrue	Assert that a is True.
IsFalse	Assert that a is False.
IsNone	Assert that a is None.
All	Assert that all of the list of predicates evaluate a as truthy.
Any	Assert that any of the list of predicates evaluate a as truthy.
In	Assert that a in b.
Contains	Assert that b in a.
ContainsOnly	Assert that values from b are the only ones contained in a.
Subset	Assert that a is a subset of b.
Superset	Assert that a is a superset of b.
Unique	Assert that a contains unique items.
InstanceOf	Assert that isinstance(a, b).
Truthy	Assert that bool(a).
Falsy	Assert that not bool(a).
Boolean	Assert that isinstance(a, bool).
String	Assert that isinstance(a, (str, unicode)).
Dict	Assert that isinstance(a, dict).
List	Assert that isinstance(a, list).
Tuple	Assert that isinstance(a, tuple).
Int	Assert that isinstance(a, int).
Float	Assert that isinstance(a, float).
Number	Assert that isinstance(a, (int, float, Decimal, long)).
NaN	Assert that not isinstance(a, (int, float, Decimal, long)).
Positive	Assert that a > 0.
Negative	Assert that a < 0.
Even	Assert that a % 2 == 0.
Odd	Assert that a % 2 != 1.
Monotone	Assert that a is monotonic with respect to b().
Increasing	Assert that a is monotonically increasing.
StrictlyIncreasing	Assert that a is strictly increasing.
Decreasing	Assert that a is monotonically decreasing.
StrictlyDecreasing	Assert that a is strictly decreasing.
Date	Assert that isinstance(a, datetime.date).
DateString	Assert that a matches the datetime format string b.

For more details, please see the full documentation at http://verify.readthedocs.org.