nose: When Plugins Fail

Plugin methods should not fail silently. When a plugin method raises an exception before or during the execution of a test, the exception will be wrapped in a nose.case.Failure instance and appear as a failing test. Exceptions raised at other times, such as in the preparation phase with prepareTestLoader or prepareTestResult, or after a test executes, in afterTest will stop the entire test run.

>>> import os
>>> import sys
>>> from nose.plugins import Plugin
>>> from nose.plugins.plugintest import run

Our first test plugins take no command-line arguments and raises AttributeError in beforeTest and afterTest.

>>> class EnabledPlugin(Plugin):
...     """Plugin that takes no command-line arguments"""
...
...     enabled = True
...
...     def configure(self, options, conf):
...         pass
...     def options(self, parser, env={}):
...         pass

>>> class FailBeforePlugin(EnabledPlugin):
...     name = "fail-before"
...
...     def beforeTest(self, test):
...         raise AttributeError()

>>> class FailAfterPlugin(EnabledPlugin):
...     name = "fail-after"
...
...     def afterTest(self, test):
...         raise AttributeError()

Running tests with the fail-before plugin enabled will result in all tests failing.

>>> support = os.path.join(os.path.dirname(__file__), 'support')
>>> suitepath = os.path.join(support, 'test_spam.py')

>>> run(argv=['nosetests', suitepath],
...     plugins=[FailBeforePlugin()])
EE
======================================================================
ERROR: test_spam.test_spam
----------------------------------------------------------------------
Traceback (most recent call last):
...
AttributeError
<BLANKLINE>
======================================================================
ERROR: test_spam.test_eggs
----------------------------------------------------------------------
Traceback (most recent call last):
...
AttributeError
<BLANKLINE>
----------------------------------------------------------------------
Ran 0 tests in ...s
<BLANKLINE>
FAILED (errors=2)

But with the fail-after plugin, the entire test run will fail.

>>> run(argv=['nosetests', suitepath],
...     plugins=[FailAfterPlugin()])
Traceback (most recent call last):
...
AttributeError

Likewise since the next plugin fails in a preparatory method, outside of test execution, the entire test run fails when the plugin is used.

>>> class FailPreparationPlugin(EnabledPlugin):
...     name = "fail-prepare"
...
...     def prepareTestLoader(self, loader):
...         raise TypeError("That loader is not my type")

>>> run(argv=['nosetests', suitepath],
...     plugins=[FailPreparationPlugin()])
Traceback (most recent call last):
...
TypeError: That loader is not my type

Plugins

Modules

Plugin Examples

nose: When Plugins Fail