ensure 0.0.3

Literate BDD assertions in Python with no magic

ensure is a set of simple assertion helpers that let you write more expressive, literate, concise, and readable Pythonic code for validating conditions. It’s inspired by should.js, expect.js, and builds on top of the unittest/JUnit assert helpers.

Because ensure is a standalone library (not part of a test framework), doesn’t monkey-patch anything, and doesn’t use the assert statement (which is liable to be turned off with the -O flag), it can be used to validate conditions in production code, not just for testing.

Aside from better looking code, a big reason to use ensure is that it provides more readable and informative error messages when things go wrong. Going forward, this will be a major development focus. You will be in control of how much information is presented in each error, which context it’s thrown from, and what introspection capabilities the exception object will have.

Installation

pip install ensure

Synopsis

from ensure import ensure

ensure({1: {2: 3}}).equals({1: {2: 3}})
ensure({1: {2: 3}}).is_not_equal_to({1: {2: 4}})
ensure(True).does_not_equal(False)
ensure(1).is_an(int)
ensure(1).is_in(range(10))
ensure(range(10)).contains(5)
ensure(True).is_a(bool)
ensure(True).is_(True)
ensure(True).is_not(False)
ensure(["spam"]).contains_none_of(["eggs", "ham"])
ensure(["train", "boat"]).contains_one_of(["train"])
ensure("abcdef").contains_some_of("abcxyz")
ensure("abcdef").contains_one_or_more_of("abcxyz")
ensure("abcdef").contains_all_of("acf")
ensure("abcd").contains_only("dcba")
ensure("abc").does_not_contain("xyz")
ensure([1, 2, 3]).contains_no(float)
ensure(dict).has_attribute('__contains__')
ensure(1).is_in(range(10))
ensure("z").is_not_in("abc")
ensure(None).is_not_in([])
ensure(1).is_true()
ensure(0).is_false()
ensure(None).is_none()
ensure(1).is_not_none()
ensure("").is_empty()
ensure([1, 2]).is_nonempty()
ensure(1.1).is_a(float)
ensure(KeyError()).is_an(Exception)
ensure({x: str(x) for x in range(5)}).is_a_nonempty(dict).of(int).to(str)
ensure({}).is_an_empty(dict)
ensure(None).is_not_a(list)
import re; ensure("abc").matches("A", flags=re.IGNORECASE)
ensure([1, 2, 3]).is_an_iterable_of(int)
ensure([1, 2, 3]).is_a_list_of(int)
ensure({1, 2, 3}).is_a_set_of(int)
ensure({1: 2, 3: 4}).is_a_mapping_of(int).to(int)
ensure({1: 2, 3: 4}).is_a_dict_of(int).to(int)
ensure(10**100).is_numeric()
ensure(lambda: 1).is_callable()
ensure("abc").has_length(3)
ensure(1).is_greater_than(0)
ensure(0).is_less_than(1)
ensure(1).is_greater_than_or_equal_to(1)
ensure(0).is_less_than_or_equal_to(0)
ensure("{x} {y}".format).called_with(x=1, y=2).equals("1 2")
ensure("{x} {y}".format).with_args(x=1, y=2).is_a(str)
ensure(dict).called_with(1, 2).raises(TypeError)
with ensure().raises(ZeroDivisionError):
    1/0
with ensure().raises_regex(NameError, "'w00t' is not defined"):
    w00t

Raising custom exceptions

from ensure import Ensure

class MyException(Exception):
    def __init__(self, e):
        pass

ensure = Ensure(error_factory=MyException)
ensure("w00t").is_an(int)

def build_fancy_exception(original_exception):
    return MyException(original_exception)

ensure = Ensure(error_factory=build_fancy_exception)
ensure("w00t").is_an(int)

Links

• Project home page (GitHub)

• Documentation (Read the Docs)

• Package distribution (Crate) (PyPI)

Bugs

Please report bugs, issues, feature requests, etc. on GitHub.

License

Licensed under the terms of the Apache License, Version 2.0.