# -*- test-case-name: twisted.internet.test.test_inlinecb -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.internet.defer.inlineCallbacks}.

Some tests for inlineCallbacks are defined in L{twisted.test.test_defgen} as
well.
"""

from __future__ import division, absolute_import

from twisted.trial.unittest import TestCase
from twisted.internet.defer import Deferred, returnValue, inlineCallbacks

class NonLocalExitTests(TestCase):
"""
It's possible for L{returnValue} to be (accidentally) invoked at a stack
level below the L{inlineCallbacks}-decorated function which it is exiting.
If this happens, L{returnValue} should report useful errors.

If L{returnValue} is invoked from a function not decorated by
L{inlineCallbacks}, it will emit a warning if it causes an
L{inlineCallbacks} function further up the stack to exit.
"""

def mistakenMethod(self):
"""
This method mistakenly invokes L{returnValue}, despite the fact that it
is not decorated with L{inlineCallbacks}.
"""
returnValue(1)


def assertMistakenMethodWarning(self, resultList):
"""
Flush the current warnings and assert that we have been told that
C{mistakenMethod} was invoked, and that the result from the Deferred
that was fired (appended to the given list) is C{mistakenMethod}'s
result. The warning should indicate that an inlineCallbacks function
called 'inline' was made to exit.
"""
self.assertEqual(resultList, [1])
warnings = self.flushWarnings(offendingFunctions=[self.mistakenMethod])
self.assertEqual(len(warnings), 1)
self.assertEqual(warnings[0]['category'], DeprecationWarning)
self.assertEqual(
warnings[0]['message'],
"returnValue() in 'mistakenMethod' causing 'inline' to exit: "
"returnValue should only be invoked by functions decorated with "
"inlineCallbacks")


def test_returnValueNonLocalWarning(self):
"""
L{returnValue} will emit a non-local exit warning in the simplest case,
where the offending function is invoked immediately.
"""
@inlineCallbacks
def inline():
self.mistakenMethod()
returnValue(2)
yield 0
d = inline()
results = []
d.addCallback(results.append)
self.assertMistakenMethodWarning(results)


def test_returnValueNonLocalDeferred(self):
"""
L{returnValue} will emit a non-local warning in the case where the
L{inlineCallbacks}-decorated function has already yielded a Deferred
and therefore moved its generator function along.
"""
cause = Deferred()
@inlineCallbacks
def inline():
yield cause
self.mistakenMethod()
returnValue(2)
effect = inline()
results = []
effect.addCallback(results.append)
self.assertEqual(results, [])
cause.callback(1)
self.assertMistakenMethodWarning(results)