src/twisted/test/test_nooldstyle.py

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.python._oldstyle._oldStyle}.
"""

from __future__ import absolute_import, division

import types
import inspect

from twisted.python.reflect import namedAny, fullyQualifiedName
from twisted.python.modules import getModule
from twisted.python.compat import _PY3, _shouldEnableNewStyle
from twisted.trial import unittest
from twisted.python import _oldstyle

_skip = None

if _PY3:
    _skip = "Not relevant on Python 3."
elif not _shouldEnableNewStyle():
    _skip = "Not running with TWISTED_NEWSTYLE=1"


forbiddenModules = [
    "twisted._threads",
    "twisted.application",
    "twisted.internet",
    "twisted.logger",
    "twisted.plugins",
    "twisted.positioning",
    "twisted.protocols.haproxy",
    "twisted.python",
    "twisted.script",
    "twisted.tap",
    "twisted.trial",
]


class SomeOldStyleClass:
    """
    I am a docstring!
    """
    bar = "baz"

    def func(self):
        """
        A function on an old style class.

        @return: "hi", for testing.
        """
        return "hi"


class SomeNewStyleClass(object):
    """
    Some new style class!
    """


class OldStyleDecoratorTests(unittest.TestCase):
    """
    Tests for L{_oldstyle._oldStyle}.
    """

    def test_makesNewStyle(self):
        """
        L{_oldstyle._oldStyle} wraps an old-style class and returns a new-style
        class that has the same functions, attributes, etc.
        """
        class SomeClassThatUsesOldStyle(SomeOldStyleClass):
            pass

        self.assertEqual(type(SomeClassThatUsesOldStyle), types.ClassType)
        updatedClass = _oldstyle._oldStyle(SomeClassThatUsesOldStyle)
        self.assertEqual(type(updatedClass), type)
        self.assertEqual(updatedClass.__bases__, (SomeOldStyleClass, object))
        self.assertEqual(updatedClass().func(), "hi")
        self.assertEqual(updatedClass().bar, "baz")


    def test_carriesAttributes(self):
        """
        The class returned by L{_oldstyle._oldStyle} has the same C{__name__},
        C{__module__}, and docstring (C{__doc__}) attributes as the original.
        """
        updatedClass = _oldstyle._oldStyle(SomeOldStyleClass)

        self.assertEqual(updatedClass.__name__, SomeOldStyleClass.__name__)
        self.assertEqual(updatedClass.__doc__, SomeOldStyleClass.__doc__)
        self.assertEqual(updatedClass.__module__, SomeOldStyleClass.__module__)


    def test_onlyOldStyleMayBeDecorated(self):
        """
        Using L{_oldstyle._oldStyle} on a new-style class on Python 2 will
        raise an exception.
        """
        with self.assertRaises(ValueError) as e:
            _oldstyle._oldStyle(SomeNewStyleClass)

        self.assertEqual(
            e.exception.args[0],
            ("twisted.python._oldstyle._oldStyle is being used to decorate a "
             "new-style class (twisted.test.test_nooldstyle.SomeNewStyleClass)"
             ". This should only be used to decorate old-style classes."))


    def test_noOpByDefault(self):
        """
        On Python 3 or on Py2 when C{TWISTED_NEWSTYLE} is not set,
        L{_oldStyle._oldStyle} is a no-op.
        """
        updatedClass = _oldstyle._oldStyle(SomeOldStyleClass)
        self.assertEqual(type(updatedClass), type(SomeOldStyleClass))
        self.assertIs(updatedClass, SomeOldStyleClass)

    if _PY3:
        test_onlyOldStyleMayBeDecorated.skip = "Only relevant on Py2."

    if _skip:
        test_makesNewStyle.skip = _skip
        test_carriesAttributes.skip = _skip
    else:
        test_noOpByDefault.skip = ("Only relevant when not running under "
                                   "TWISTED_NEWSTYLE=1")


class NewStyleOnly(object):
    """
    A base testclass that takes a module and tests if the classes defined
    in it are old-style.

    CAVEATS: This is maybe slightly dumb. It doesn't look inside functions, for
    classes defined there, or nested classes.
    """
    skip = _skip

    def test_newStyleClassesOnly(self):
        """
        Test that C{self.module} has no old-style classes in it.
        """
        try:
            module = namedAny(self.module)
        except ImportError as e:
            raise unittest.SkipTest("Not importable: {}".format(e))

        oldStyleClasses = []

        for name, val in inspect.getmembers(module):
            if hasattr(val, "__module__") \
               and val.__module__ == self.module:
                if isinstance(val, types.ClassType):
                    oldStyleClasses.append(fullyQualifiedName(val))

        if oldStyleClasses:

            self.todo = "Not all classes are made new-style yet. See #8243."

            for x in forbiddenModules:
                if self.module.startswith(x):
                    delattr(self, "todo")

            raise unittest.FailTest(
                "Old-style classes in {module}: {val}".format(
                    module=self.module,
                    val=", ".join(oldStyleClasses)))


def _buildTestClasses(_locals):
    """
    Build the test classes that use L{NewStyleOnly}, one class per module.

    @param _locals: The global C{locals()} dict.
    """
    for x in getModule("twisted").walkModules():

        ignoredModules = [
            "twisted.test.reflect_helper",
            "twisted.internet.test.process_",
            "twisted.test.process_"
        ]

        isIgnored = [x.name.startswith(ignored) for ignored in ignoredModules]

        if True in isIgnored:
            continue


        class Test(NewStyleOnly, unittest.TestCase):
            """
            @see: L{NewStyleOnly}
            """
            module = x.name

        acceptableName = x.name.replace(".", "_")
        Test.__name__ = acceptableName
        if hasattr(Test, "__qualname__"):
            Test.__qualname__ = acceptableName
        _locals.update({acceptableName: Test})


_buildTestClasses(locals())