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

"""
Test cases for L{twisted.internet.defer} on Python 3.5 and later.

This file is loaded by C{test_defer.py} only when running on an
interpreter version that supports the C{async} and C{await} keywords.
"""


import functools


from twisted.internet import defer
from twisted.trial import unittest



def ensuringDeferred(f):
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        result = f(*args, **kwargs)
        return defer.ensureDeferred(result)
    return wrapper



class DeferredTestsAsync(unittest.TestCase):


    @ensuringDeferred
    async def test_asyncWithLock(self):
        """
        L{defer.DeferredLock} can be used as an asynchronous context manager.
        """
        lock = defer.DeferredLock()
        async with lock:
            self.assertTrue(lock.locked)
            d = lock.acquire()
            d.addCallback(lambda _: lock.release())
            self.assertTrue(lock.locked)
            self.assertFalse(d.called)
        self.assertTrue(d.called)
        await d
        self.assertFalse(lock.locked)


    @ensuringDeferred
    async def test_asyncWithSemaphore(self):
        """
        L{defer.DeferredSemaphore} can be used as an asynchronous context manager.
        """
        sem = defer.DeferredSemaphore(3)

        async with sem:
            self.assertEqual(sem.tokens, 2)
            async with sem:
                self.assertEqual(sem.tokens, 1)
                d1 = sem.acquire()
                d2 = sem.acquire()
                self.assertEqual(sem.tokens, 0)
                self.assertTrue(d1.called)
                self.assertFalse(d2.called)
            self.assertEqual(sem.tokens, 0)
            self.assertTrue(d2.called)
            d1.addCallback(lambda _: sem.release())
            d2.addCallback(lambda _: sem.release())
            await d1
            await d2
            self.assertEqual(sem.tokens, 2)
        self.assertEqual(sem.tokens, 3)

    @ensuringDeferred
    async def test_asyncWithLockException(self):
        """
        C{defer.DeferredLock} correctly propagates exceptions when
        used as an asynchronous context manager.
        """
        lock = defer.DeferredLock()
        with self.assertRaisesRegexp(Exception, 'some specific exception'):
            async with lock:
                self.assertTrue(lock.locked)
                raise Exception('some specific exception')
        self.assertFalse(lock.locked)