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corejet.core 1.0.2

Defines test infrastructure for building CoreJet tests

CoreJet

CoreJet is a Behaviour Driven Testing specification and approach, with implementations in Python and Java. See http://corejet.org for more details.

This package provides core CoreJet functionality in Python. You will probably also be interested in corejet.testrunner and possibly corejet.jira.

Why not Cucumber?

There are various packages that implement a similar style of BDD testing in Python, usually based on Cucumber. CoreJet has one important philosophical difference: Instead of writing stories and scenarios in plain text files, they are intended to be managed as part of a requirements management system such as JIRA (hence corejet.jira). This manages epics, stories and scenarios, as well as the lifecycle and metadata surrounding requirements: whether they are open or closed, how big (in story points) they are, and how valuable they are to business users (priority).

A "requirements catalogue source" extracts them from this system into either an intermediary XML format (see below) or directly into the CoreJet data model (again, see below). The test runner (corejet.testrunner) first fetches the current requirements catalogue, then executes all CoreJet tests, matching up stories (by id) and scenarios (by name) and setting the status of each to either "pass", "fail", "pending" (not yet implemented) or "mismatch" (a given/when/then step in a scenario is out of sync with the requirements management system).

The output of this analysis is written to an augmented CoreJet XML file. This is then used to generate a visualisation of the state of the project (see corejet.visualization), with colour coding to indicate how much of the project is in fact complete, where "complete" means it has passing automated tests that accurately represent the business' acceptance criteria.

Installation

You can install corejet.core as a dependency of your package, e.g. in setup.py adding:

install_requires=['corejet.core']

or, if you prefer to keep your tests in an extra:

extras_require = {'test': ['corejet.core']}

Note however that corejet.core relies on the lxml library. This is sometimes a bit tricky to install on OS X and older Linux platforms. If you are using Buildout to install your packages, you may want to use z3c.recipe.lxml to install lxml: Add lxml as the first item in your parts list and then add this section:

[lxml]
recipe = z3c.recipe.staticlxml
egg = lxml

Test syntax

To write CoreJet tests in Python, you can use the decorators found in this package in combination with unittest style test cases. To do this, you should depend on corejet.core in your own package (or at least in its list of test dependencies), and probably also unittest2 if working in Python 2.6 or earlier.

Here is an example:

import unittest2 as unittest
from corejet.core import Scenario, story, scenario, given, when, then

@story(id="S1", title="As a user, I can log in")
class Login(unittest.TestCase):

    @scenario("Invalid username")
    class InvalidUsername(Scenario):

        @given("A user 'joebloggs' with password 'secret'")
        def setupUser(self):
            # Some precondition logic, e.g.
            createUser('jobloggs', 'secret')

        @when("Entering the username 'jobloggs' and password 'secret'")
        def attemptLogin(self):
            # Call some action logic, e.g.
            loginAs('jobloggs', 'secret')

        @then("An error is shown")
        def checkOutput(self):
            # Perform some assertion, e.g.
            errorMessages = getErrorMessages()
            self.assertTrue("Invalid username" in errorMessages)

    @scenario("Invalid password")
    class InvalidPassword(Scenario):

        @given("A user 'joebloggs' with password 'secret'")
        def setupUser(self):
            # Some precondition logic, e.g.
            createUser('jobloggs', 'secret')

        @when("Entering the username 'joebloggs' and password 'uhoh'")
        def attemptLogin(self):
            # Call some action logic, e.g.
            loginAs('joebloggs', 'uhph')

        @then("An error is shown")
        def checkOutput(self):
            # Perform some assertion, e.g.
            errorMessages = getErrorMessages()
            self.assertTrue("Invalid password" in errorMessages)

You can have as many or as few scenarios as you want. The Scenario base class provides access to an attribute self.story, which is an instance of the outer @story-annotated test case class. This allows access to shared attributes or state. You can also use standard unittest `` conventions like ``setUp() and tearDown() on the outer class (but not on the Scenario classes) to manage your test fixtures.

In fact, at runtime, each inner scenario class is turned into a standard method on the outer story class with the name test_<ScenarioName>(), which, when called, will call each of the @given-annotated methods in the inner class, then each of the @when-annotated methods, then each of the @then-annotated methods.

The reason for this trick is to ensure standard test collectors work. In fact, a CoreJet test should work with any standard testrunner that can execute unittest tests.

Of course, the main reason to use CoreJet is to generate a report of completed functional coverage. To do this, you can use the test runner in corejet.testrunner combined with a requirements catalogue source. See that package for details.

Data model

The standard CoreJet data model is represented in this package in the module corejet.core.model, and described by the interfaces in corejet.core.interfaces. There main class is the RequirementsCatalogue, which contains a list of Epic object, which in turn contain a list of Story objects, which in turn contain a list of Scenario objects, which in turn contain three lists (given, when and then) of Step objects.

See the documentation in the source for more details.

XML parsing and serialization

The RequirementsCatalog class provides methods populate() and write(), which can read and write, respectively, a standard CoreJet XML file to initialise or serialise the catalogue.

Here is an example file for the one story and and two scenarios above, contained in a fictitious epic:

<requirementscatalogue project="Acme Corp" extractTime="2011-05-15T19:00:00">
  <epic id="E1" title="User management">
    <story id="S1" title="As a user, I can log in" requirementStatus="closed" resolution="fixed" priority="high">
      <scenario name="Invalid username">
        <given>A user 'joebloggs' with password 'secret'</given>
        <when>Entering the username 'jobloggs' and password 'secret'</when>
        <then>An error is shown</then>
      </scenario>
      <scenario name="Invalid password">
        <given>A user 'joebloggs' with password 'secret'</given>
        <when>Entering the username 'joebloggs' and password 'uhoh'</when>
        <then>An error is shown</then>
      </scenario>
    </story>
  </epic>
</requirementscatalogue>

Scenario parser

Scenarios are often written in "Gherkin" syntax (as per the Cucumber framework, form which CoreJet is partly inspired).

Scenarios can be written in plain text like so:

Scenario: Invalid username
Given A user 'joebloggs' with password 'secret'
When Entering the username 'jobloggs' and password 'secret'
Then An error is shown

Scenario: Invalid password
Given A user 'joebloggs' with password 'secret'
When Entering the username 'joebloggs' and password 'uhoh'
Then An error is shown

Scenario: Cancel button
Given A user 'joebloggs' with password 'secret'
When Entering the username 'joebloggs' and password 'uhoh'
 And Clicking the 'cancel' button
Then The user is taken away from the page
 And A warning is shown

Scenarios may be preceded by a background description composed of one or more "Given" clauses affecting every scenario:

Given I'm logged in
 And I've got superuser privileges

Scenario: ...

In addition, there is basic support for "Scenario Outline" with "Examples".

The full Gherkin syntax is more involved, but to parse this simplified style of scenarios and append them to a story, you can use the function corejet.core.parser.appendScenarios. It takes a Story and a string containing the acceptance criteria text as its two arguments.

The parser is relatively forgiving, but note:

  • The parser is case-insensitive
  • Zero or more scenarios may be present
  • Scenarios must start with "Scenario: " followed by a name
  • The "Given" clause is optional, but must come first in a scenario
  • The "When" clause is required, and must come before the "Then" clause
  • The "Then"" clause is also required
  • An "And" or "But" clause can come after any "Given", "When" or "Then", but not first.

Generating test skeletons

corejet.core ships with an XSLT stylesheet for generating test skeletons for Python unittest. If you are using buildout, you can install a helper script for executing the XSLT-transformation with:

[corejet2py]
recipe = zc.recipe.rgg
eggs = corejet.core
scripts = corejet2py

And execute it with:

bin/corejet2py path/to/corejet.xml

Try bin/corejet2py --help for more information.

Changelog

1.0.2 (2012-05-30)

  • Fixed test skeleton generation XSLT to strip extra whitespaces. [datakurre]

1.0.1 (2012-05-27)

  • Added helper script for generating test skeletons from test reports. Added 'argparse' into requirements. [datakurre]

1.0.0

  • Added Finnish language support ('# language: fi') [datakurre]
  • Added parser support for Cucumber-like 'language' keyword [datakurre]
  • Added parser support for 'Scenario Outline' and 'Examples' [datakurre]
  • Added new step keyword but as on alias to and [datakurre]
  • Modified decorators to name test modules and methods by normalizing their respective titles [datakurre]
  • Completed support for story-level steps [datakurre]
  • Ensure quotes (") are converted into apostrophes (') [datakurre]
  • Fixed corejet-to-python.xsl to produce runnable test skeletons [datakurre]

1.0a4

  • Ensure multiple steps of the same type always execute in the right sequence. [optilude]

1.0a3

  • Fix broken package [optilude]

1.0a1

  • First release [optilude]
 
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