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

"""
Tests for L{twisted.python.monkey}.
"""

from __future__ import division, absolute_import

from twisted.trial import unittest
from twisted.python.monkey import MonkeyPatcher


class TestObj:
def __init__(self):
self.foo = 'foo value'
self.bar = 'bar value'
self.baz = 'baz value'



class MonkeyPatcherTest(unittest.SynchronousTestCase):
"""
Tests for L{MonkeyPatcher} monkey-patching class.
"""

def setUp(self):
self.testObject = TestObj()
self.originalObject = TestObj()
self.monkeyPatcher = MonkeyPatcher()


def test_empty(self):
"""
A monkey patcher without patches shouldn't change a thing.
"""
self.monkeyPatcher.patch()

# We can't assert that all state is unchanged, but at least we can
# check our test object.
self.assertEqual(self.originalObject.foo, self.testObject.foo)
self.assertEqual(self.originalObject.bar, self.testObject.bar)
self.assertEqual(self.originalObject.baz, self.testObject.baz)


def test_constructWithPatches(self):
"""
Constructing a L{MonkeyPatcher} with patches should add all of the
given patches to the patch list.
"""
patcher = MonkeyPatcher((self.testObject, 'foo', 'haha'),
(self.testObject, 'bar', 'hehe'))
patcher.patch()
self.assertEqual('haha', self.testObject.foo)
self.assertEqual('hehe', self.testObject.bar)
self.assertEqual(self.originalObject.baz, self.testObject.baz)


def test_patchExisting(self):
"""
Patching an attribute that exists sets it to the value defined in the
patch.
"""
self.monkeyPatcher.addPatch(self.testObject, 'foo', 'haha')
self.monkeyPatcher.patch()
self.assertEqual(self.testObject.foo, 'haha')


def test_patchNonExisting(self):
"""
Patching a non-existing attribute fails with an C{AttributeError}.
"""
self.monkeyPatcher.addPatch(self.testObject, 'nowhere',
'blow up please')
self.assertRaises(AttributeError, self.monkeyPatcher.patch)


def test_patchAlreadyPatched(self):
"""
Adding a patch for an object and attribute that already have a patch
overrides the existing patch.
"""
self.monkeyPatcher.addPatch(self.testObject, 'foo', 'blah')
self.monkeyPatcher.addPatch(self.testObject, 'foo', 'BLAH')
self.monkeyPatcher.patch()
self.assertEqual(self.testObject.foo, 'BLAH')
self.monkeyPatcher.restore()
self.assertEqual(self.testObject.foo, self.originalObject.foo)


def test_restoreTwiceIsANoOp(self):
"""
Restoring an already-restored monkey patch is a no-op.
"""
self.monkeyPatcher.addPatch(self.testObject, 'foo', 'blah')
self.monkeyPatcher.patch()
self.monkeyPatcher.restore()
self.assertEqual(self.testObject.foo, self.originalObject.foo)
self.monkeyPatcher.restore()
self.assertEqual(self.testObject.foo, self.originalObject.foo)


def test_runWithPatchesDecoration(self):
"""
runWithPatches should run the given callable, passing in all arguments
and keyword arguments, and return the return value of the callable.
"""
log = []

def f(a, b, c=None):
log.append((a, b, c))
return 'foo'

result = self.monkeyPatcher.runWithPatches(f, 1, 2, c=10)
self.assertEqual('foo', result)
self.assertEqual([(1, 2, 10)], log)


def test_repeatedRunWithPatches(self):
"""
We should be able to call the same function with runWithPatches more
than once. All patches should apply for each call.
"""
def f():
return (self.testObject.foo, self.testObject.bar,
self.testObject.baz)

self.monkeyPatcher.addPatch(self.testObject, 'foo', 'haha')
result = self.monkeyPatcher.runWithPatches(f)
self.assertEqual(
('haha', self.originalObject.bar, self.originalObject.baz), result)
result = self.monkeyPatcher.runWithPatches(f)
self.assertEqual(
('haha', self.originalObject.bar, self.originalObject.baz),
result)


def test_runWithPatchesRestores(self):
"""
C{runWithPatches} should restore the original values after the function
has executed.
"""
self.monkeyPatcher.addPatch(self.testObject, 'foo', 'haha')
self.assertEqual(self.originalObject.foo, self.testObject.foo)
self.monkeyPatcher.runWithPatches(lambda: None)
self.assertEqual(self.originalObject.foo, self.testObject.foo)


def test_runWithPatchesRestoresOnException(self):
"""
Test runWithPatches restores the original values even when the function
raises an exception.
"""
def _():
self.assertEqual(self.testObject.foo, 'haha')
self.assertEqual(self.testObject.bar, 'blahblah')
raise RuntimeError("Something went wrong!")

self.monkeyPatcher.addPatch(self.testObject, 'foo', 'haha')
self.monkeyPatcher.addPatch(self.testObject, 'bar', 'blahblah')

self.assertRaises(RuntimeError, self.monkeyPatcher.runWithPatches, _)
self.assertEqual(self.testObject.foo, self.originalObject.foo)
self.assertEqual(self.testObject.bar, self.originalObject.bar)