pytest-describe 0.10

Describe-style plugin for py.test

pytest-describe is a plugin for py.test that allows tests to be written in arbitrary nested describe-blocks, similar to RSpec (Ruby) and Jasmine (JavaScript).

The main inspiration for this was a video by Gary Bernhardt.

pip install pytest-describe

def describe_list():

    @pytest.fixture
    def list():
        return []

    def describe_append():

        def adds_to_end_of_list(list):
            list.append('foo')
            list.append('bar')
            assert list == ['foo', 'bar']

    def describe_remove():

        @pytest.fixture
        def list():
            return ['foo', 'bar']

        def removes_item_from_list(list):
            list.remove('foo')
            assert list == ['bar']

Why bother?

I’ve found that quite often my tests have one “dimention” more than my production code. The production code is organized into packages, modules, classes (sometimes), and functions. I like to organize my tests in the same way, but tests also have different _cases_ for each function. This tends to end up with a set of tests for each module (or class), where each test has to name both a function and a _case_. For instance:

def test_my_function_with_default_arguments():
def test_my_function_with_some_other_arguments():
def test_my_function_throws_exception():
def test_my_function_handles_exception():
def test_some_other_function_returns_true():
def test_some_other_function_returns_false():

(and so on)

It’s much nicer to do this:

def describe_my_function():
    def with_default_arguments():
    def with_some_other_arguments():
    def it_throws_exception():
    def it_handles_exception():

def describe_some_other_function():
    def it_returns_true():
    def it_returns_false():

It has the additional advantage that you can have marks and fixtures that apply locally to each group of test function.

With pytest, it’s possible to organize tests in a similar way with classes. However, I think classes are akward. I dont think the convention of using camel-case names for classes fit very well when testing functions in different cases. In addition, every test function must take a “self” argument that is never used.