#!/usr/bin/env python

# coding: utf-8

"""

This module contains a helper for writing test cases that need to compare messages.

"""

from __future__ import absolute_import, print_function

from copy import copy

class ComparingMessagesTestCase(object):

"""

Must be extended by a class also extending a unittest.TestCase.

.. note:: This class does not extend unittest.TestCase so it does not get

run as a test itself.

"""

def __init__(self, allowed_timestamp_delta=0.0, preserves_channel=True):

"""

:param float or int or None allowed_timestamp_delta: directly passed to :meth:`can.Message.equals`

:param bool preserves_channel: if True, checks that the channel attribute is preserved

"""

self.allowed_timestamp_delta = allowed_timestamp_delta

self.preserves_channel = preserves_channel

def assertMessageEqual(self, message_1, message_2):

"""

Checks that two messages are equal, according to the given rules.

"""

if message_1.equals(message_2, timestamp_delta=self.allowed_timestamp_delta):

return

elif self.preserves_channel:

print("Comparing: message 1: {!r}".format(message_1))

print(" message 2: {!r}".format(message_2))

self.fail("messages are unequal with allowed timestamp delta {}".format(self.allowed_timestamp_delta))

else:

message_2 = copy(message_2) # make sure this method is pure

message_2.channel = message_1.channel

if message_1.equals(message_2, timestamp_delta=self.allowed_timestamp_delta):

return

else:

print("Comparing: message 1: {!r}".format(message_1))

print(" message 2: {!r}".format(message_2))

self.fail("messages are unequal with allowed timestamp delta {} even when ignoring channels" \

.format(self.allowed_timestamp_delta))