Expected GOES FIRST

expected

from nose.tools import assert_equals  # pip install nosetests

assert_equals("first", "second")
# Nothing fancy here, just default string comparison
# AssertionError: 'first' != 'second'

# Lets compare a dictionary
assert_equals({'a': 'foo'}, {'a': 'bar'})
# This produces a cool little diff
# AssertionError: {'a': 'foo'} != {'a': 'bar'}
# - {'a': 'foo'}
# ?        ^^^
#
# + {'a': 'bar'}
# ?        ^^^

# When our test fails we want to know how the test result deviates from the expected result.
# Convention in diff output (as above) puts the 'baseline' value first
# So, kids, assert_equals(expected, result) for great justice