Usage examples

To make use of compare, simply import the expect() function into your module. You may then use the function to handle any comparisons and assertions you wish to make about values in your code.

Verifying expectations with the base matchers

Below is a simple example showing how you use the builtin matchers to craft readable specifications for your code:

>>> from compare import expect

>>> fruit = 'Orange'

>>> expect(fruit).to_equal('Orange')
>>> expect(fruit).to_equal('Apple')
Traceback (most recent call last):
    ...
UnmetExpectation: Expected 'Orange' to equal 'Apple'

Verifying expectations with the “rich comparison” matchers

If you find some of the base matchers too verbose for your examples, you may take advantage of the alternative syntax through the rich comparison matchers. Here is what the previous example would look like with rich comparisons:

>>> from compare import expect

>>> fruit = 'Orange'

>>> expect(fruit) == 'Orange'
>>> expect(fruit) == 'Apple'
Traceback (most recent call last):
    ...
UnmetExpectation: Expected 'Orange' to equal 'Apple'

To illustrate the major benefit of rich comparason matchers, note that the following expectations achieve the same goal.:

>>> from compare import expect

>>> expect(960).to_be_greater_than_or_equal_to(950)
>>> expect(960) >= 950

Creating and using custom matchers

A compare matcher is a regular python function that can be wired into the Expr class. You may extend compare with custom matchers that make make your examples succinct and easy to follow:

>>> from compare import expect, matcher, ensure

>>> @matcher
... def to_be_citrus(self):
...     ensure(self.value in ['Orange'], True,
...         "Expected %r to be a citrus fruit" % self.value)

>>> fruit = 'Orange'
>>> expect(fruit).to_be_citrus()