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