Introduction

Library to convert BDD features into Python unittest.TestCase classes. Run the tests with your favorite test runner, like pytest, unittest or nose. See the demo folder for an example.

Example

Let’s take a calculator as an example. Create a plain text file called calculator.feature containing the BDD-style feature description:

Feature: Basic math operations
 Test addition

Scenario: add
 Given the value 10
 When adding 7
 Then the result is 17

Scenario: add a negative value
 Given the value 19
 When adding -11
 Then the result is 8

This is the text you can discuss with the customer and agree on. Next write a backing file called test_calculator.py containing the code to run this feature:

import os
from bdd import Environment
from calculator import Calculator

env = Environment()
env.context.calculator = Calculator()

@env.given('the value {:d}')
def step(context, value):
    context.calculator.value = value

@env.when('adding {:d}')
def step(context, value):
    context.calculator.add(value)

@env.then('the result is {:d}')
def step(context, value):
    assert context.calculator.value == value

def rel(p):
    this_dir = os.path.dirname(os.path.abspath(__file__))
    return os.path.join(this_dir, p)

CalculatorTestCase = env.load_feature_as_testcase('calculator.feature')

Finally, write the actual production code to implement the calculator, in a file called calculator.py:

class Calculator:
    def __init__(self):
        self.value = 0

    def add(self, value):
        self.value += value

Now run the tests with, for example, pytest:

$ python -m pytest test_calculator.py -v
=========== test session starts ===========================
platform linux -- Python 3.5.1, pytest-2.9.1
collected 2 items

test_calculator.py::CalculatorTestCase::test_scenario_0 <- bdd.py PASSED
test_calculator.py::CalculatorTestCase::test_scenario_1 <- bdd.py PASSED

References

A really good python bdd library is behave.

Changelog

0.2

• Add tag support

0.1 (Jun 2, 2016)

• Initial release