IPython/core/tests/test_hooks.py

# -*- coding: utf-8 -*-
"""Tests for CommandChainDispatcher."""

from __future__ import absolute_import

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

import nose.tools as nt
from IPython.core.error import TryNext
from IPython.core.hooks import CommandChainDispatcher

#-----------------------------------------------------------------------------
# Local utilities
#-----------------------------------------------------------------------------

# Define two classes, one which succeeds and one which raises TryNext. Each
# sets the attribute `called` to True when it is called.
class Okay(object):
    def __init__(self, message):
        self.message = message
        self.called = False
    def __call__(self):
        self.called = True
        return self.message

class Fail(object):
    def __init__(self, message):
        self.message = message
        self.called = False
    def __call__(self):
        self.called = True
        raise TryNext(self.message)

#-----------------------------------------------------------------------------
# Test functions
#-----------------------------------------------------------------------------

def test_command_chain_dispatcher_ff():
    """Test two failing hooks"""
    fail1 = Fail(u'fail1')
    fail2 = Fail(u'fail2')
    dp = CommandChainDispatcher([(0, fail1),
                                 (10, fail2)])

    try:
        dp()
    except TryNext as e:
        nt.assert_equal(str(e), u'fail2')
    else:
        assert False, "Expected exception was not raised."

    nt.assert_true(fail1.called)
    nt.assert_true(fail2.called)

def test_command_chain_dispatcher_fofo():
    """Test a mixture of failing and succeeding hooks."""
    fail1 = Fail(u'fail1')
    fail2 = Fail(u'fail2')
    okay1 = Okay(u'okay1')
    okay2 = Okay(u'okay2')

    dp = CommandChainDispatcher([(0, fail1),
                                 # (5, okay1), # add this later
                                 (10, fail2),
                                 (15, okay2)])
    dp.add(okay1, 5)

    nt.assert_equal(dp(), u'okay1')

    nt.assert_true(fail1.called)
    nt.assert_true(okay1.called)
    nt.assert_false(fail2.called)
    nt.assert_false(okay2.called)

def test_command_chain_dispatcher_eq_priority():
    okay1 = Okay(u'okay1')
    okay2 = Okay(u'okay2')
    dp = CommandChainDispatcher([(1, okay1)])
    dp.add(okay2, 1)