211 lines
7.1 KiB
Python
211 lines
7.1 KiB
Python
"""
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ErrorClass Plugins
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------------------
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ErrorClass plugins provide an easy way to add support for custom
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handling of particular classes of exceptions.
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An ErrorClass plugin defines one or more ErrorClasses and how each is
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handled and reported on. Each error class is stored in a different
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attribute on the result, and reported separately. Each error class must
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indicate the exceptions that fall under that class, the label to use
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for reporting, and whether exceptions of the class should be
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considered as failures for the whole test run.
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ErrorClasses use a declarative syntax. Assign an ErrorClass to the
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attribute you wish to add to the result object, defining the
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exceptions, label and isfailure attributes. For example, to declare an
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ErrorClassPlugin that defines TodoErrors (and subclasses of TodoError)
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as an error class with the label 'TODO' that is considered a failure,
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do this:
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>>> class Todo(Exception):
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... pass
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>>> class TodoError(ErrorClassPlugin):
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... todo = ErrorClass(Todo, label='TODO', isfailure=True)
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The MetaErrorClass metaclass translates the ErrorClass declarations
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into the tuples used by the error handling and reporting functions in
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the result. This is an internal format and subject to change; you
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should always use the declarative syntax for attaching ErrorClasses to
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an ErrorClass plugin.
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>>> TodoError.errorClasses # doctest: +ELLIPSIS
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((<class ...Todo...>, ('todo', 'TODO', True)),)
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Let's see the plugin in action. First some boilerplate.
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>>> import sys
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>>> import unittest
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>>> try:
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... # 2.7+
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... from unittest.runner import _WritelnDecorator
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... except ImportError:
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... from unittest import _WritelnDecorator
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...
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>>> buf = _WritelnDecorator(sys.stdout)
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Now define a test case that raises a Todo.
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>>> class TestTodo(unittest.TestCase):
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... def runTest(self):
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... raise Todo("I need to test something")
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>>> case = TestTodo()
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Prepare the result using our plugin. Normally this happens during the
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course of test execution within nose -- you won't be doing this
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yourself. For the purposes of this testing document, I'm stepping
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through the internal process of nose so you can see what happens at
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each step.
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>>> plugin = TodoError()
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>>> from nose.result import _TextTestResult
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>>> result = _TextTestResult(stream=buf, descriptions=0, verbosity=2)
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>>> plugin.prepareTestResult(result)
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Now run the test. TODO is printed.
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>>> _ = case(result) # doctest: +ELLIPSIS
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runTest (....TestTodo) ... TODO: I need to test something
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Errors and failures are empty, but todo has our test:
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>>> result.errors
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[]
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>>> result.failures
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[]
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>>> result.todo # doctest: +ELLIPSIS
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[(<....TestTodo testMethod=runTest>, '...Todo: I need to test something\\n')]
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>>> result.printErrors() # doctest: +ELLIPSIS
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<BLANKLINE>
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======================================================================
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TODO: runTest (....TestTodo)
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----------------------------------------------------------------------
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Traceback (most recent call last):
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...
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...Todo: I need to test something
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<BLANKLINE>
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Since we defined a Todo as a failure, the run was not successful.
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>>> result.wasSuccessful()
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False
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"""
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from nose.pyversion import make_instancemethod
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from nose.plugins.base import Plugin
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from nose.result import TextTestResult
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from nose.util import isclass
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class MetaErrorClass(type):
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"""Metaclass for ErrorClassPlugins that allows error classes to be
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set up in a declarative manner.
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"""
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def __init__(self, name, bases, attr):
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errorClasses = []
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for name, detail in list(attr.items()):
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if isinstance(detail, ErrorClass):
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attr.pop(name)
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for cls in detail:
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errorClasses.append(
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(cls, (name, detail.label, detail.isfailure)))
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super(MetaErrorClass, self).__init__(name, bases, attr)
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self.errorClasses = tuple(errorClasses)
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class ErrorClass(object):
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def __init__(self, *errorClasses, **kw):
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self.errorClasses = errorClasses
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try:
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for key in ('label', 'isfailure'):
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setattr(self, key, kw.pop(key))
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except KeyError:
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raise TypeError("%r is a required named argument for ErrorClass"
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% key)
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def __iter__(self):
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return iter(self.errorClasses)
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class ErrorClassPlugin(Plugin, metaclass=MetaErrorClass):
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"""
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Base class for ErrorClass plugins. Subclass this class and declare the
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exceptions that you wish to handle as attributes of the subclass.
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"""
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score = 1000
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errorClasses = ()
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def addError(self, test, err):
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err_cls, a, b = err
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if not isclass(err_cls):
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return
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classes = [e[0] for e in self.errorClasses]
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if [c for c in classes if issubclass(err_cls, c)]:
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return True
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def prepareTestResult(self, result):
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if not hasattr(result, 'errorClasses'):
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self.patchResult(result)
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for cls, (storage_attr, label, isfail) in self.errorClasses:
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if cls not in result.errorClasses:
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storage = getattr(result, storage_attr, [])
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setattr(result, storage_attr, storage)
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result.errorClasses[cls] = (storage, label, isfail)
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def patchResult(self, result):
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result.printLabel = print_label_patch(result)
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result._orig_addError, result.addError = \
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result.addError, add_error_patch(result)
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result._orig_wasSuccessful, result.wasSuccessful = \
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result.wasSuccessful, wassuccessful_patch(result)
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if hasattr(result, 'printErrors'):
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result._orig_printErrors, result.printErrors = \
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result.printErrors, print_errors_patch(result)
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if hasattr(result, 'addSkip'):
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result._orig_addSkip, result.addSkip = \
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result.addSkip, add_skip_patch(result)
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result.errorClasses = {}
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def add_error_patch(result):
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"""Create a new addError method to patch into a result instance
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that recognizes the errorClasses attribute and deals with
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errorclasses correctly.
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"""
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return make_instancemethod(TextTestResult.addError, result)
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def print_errors_patch(result):
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"""Create a new printErrors method that prints errorClasses items
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as well.
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"""
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return make_instancemethod(TextTestResult.printErrors, result)
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def print_label_patch(result):
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"""Create a new printLabel method that prints errorClasses items
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as well.
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"""
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return make_instancemethod(TextTestResult.printLabel, result)
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def wassuccessful_patch(result):
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"""Create a new wasSuccessful method that checks errorClasses for
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exceptions that were put into other slots than error or failure
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but that still count as not success.
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"""
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return make_instancemethod(TextTestResult.wasSuccessful, result)
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def add_skip_patch(result):
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"""Create a new addSkip method to patch into a result instance
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that delegates to addError.
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"""
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return make_instancemethod(TextTestResult.addSkip, result)
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if __name__ == '__main__':
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import doctest
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doctest.testmod()
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