affinitic.verifyinterface 0.1

Verify interface contract for all implements/classImplements declaration

Introduction

What’s the use to declare an interface if your class doesn’t implement correctly the interface ?

Of course you should verify that in a test but if you don’t want to write a test to check that all your code really implements the promised interfaces use this package.

It’s a simple patch that calls zope.interface.verify.verifyClass once you declare implementing an interface and print the BrokenImplementation or BrokenMethodImplementation as a warning (if any).

Simple example in testrunner:

By default the egg enable interface contract verification for zope.interface.implements and zope.interface.classImplements that are present in all your packages:

>>> write('buildout.cfg',
... """
... [buildout]
... parts =
...     test
...
... [test]
... recipe = zc.recipe.testrunner
... eggs = affinitic.verifyinterface
...        zope.exceptions
... defaults = ['-m', 'module']
... """)

>>> print system(buildout)
Installing test.
...

>>> from os.path import join
>>> print system(join('bin', 'test')),
<class 'affinitic.verifyinterface.tests.test_module1.Foo'> failed implementing <InterfaceClass affinitic.verifyinterface.tests.test_module1.IFoo>: An object has failed to implement interface <InterfaceClass affinitic.verifyinterface.tests.test_module1.IFoo>
<BLANKLINE>
        The bla attribute was not provided.
<BLANKLINE>
<class 'affinitic.verifyinterface.tests.test_module2.Bar'> failed implementing <InterfaceClass affinitic.verifyinterface.tests.test_module2.IBar>: An object has failed to implement interface <InterfaceClass affinitic.verifyinterface.tests.test_module2.IBar>
<BLANKLINE>
        The bla attribute was not provided.
<BLANKLINE>
Running zope.testing.testrunner.layer.UnitTests tests:
  Set up zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
  Ran 2 tests with 0 failures and 0 errors in 0.000 seconds.
Tearing down left over layers:
  Tear down zope.testing.testrunner.layer.UnitTests in 0.000 seconds.

Limit verifications

But you can limit the package where this verification needs to be done (sometimes you don’t care that a package you depend on didn’t implement correctly an interface).

This is done by adding an environment variable verifyinterface where you specify what packages/modules (separated by n as usual) you accept to verify interfaces.

Here is a simple example where I only want to have warning for bad implementation of interfaces used by module1:

>>> write('buildout.cfg',
... """
... [buildout]
... parts =
...     test
...
... [test]
... recipe = zc.recipe.testrunner
... eggs = affinitic.verifyinterface
...        zope.exceptions
... defaults = ['-m', 'module']
... environment = testenv
...
... [testenv]
... verifyinterface = affinitic.verifyinterface.tests.test_module1
... """)

>>> print system(buildout)
Uninstalling test.
Installing test.
...

>>> from os.path import join
>>> print system(join('bin', 'test'))
<class 'affinitic.verifyinterface.tests.test_module1.Foo'> failed implementing <InterfaceClass affinitic.verifyinterface.tests.test_module1.IFoo>: An object has failed to implement interface <InterfaceClass affinitic.verifyinterface.tests.test_module1.IFoo>
<BLANKLINE>
        The bla attribute was not provided.
<BLANKLINE>
Running zope.testing.testrunner.layer.UnitTests tests:
  Set up zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
  Ran 2 tests with 0 failures and 0 errors in 0.000 seconds.
Tearing down left over layers:
  Tear down zope.testing.testrunner.layer.UnitTests in 0.000 seconds.

Changelog

0.1 (2009-12-18)

• Initial release