CODEWITHSUNDEEP
assertpytest
donnut
donnut

Reputation: 720

custom assert in pytest should overrule standard assert

I wrote a custom assert function to compare items in two lists such that the order is not important, using pytest_assertrepr_compare. This works fine and reports a failure when the content of the lists differ.

However, if the custom assert passes, it fails on the default '==' assert because item 0 of one list is unequal to item 0 of the other list.

Is there a way to prevent the default assert to kick in?

assert ['a', 'b', 'c'] == ['b', 'a', 'c'] # custom assert passes 
                                          # default assert fails

The custom assert function is:

def pytest_assertrepr_compare(config, op, left, right):
    equal = True
    if op == '==' and isinstance(left, list) and isinstance(right, list):
        if len(left) != len(right):
            equal = False
        else:
            for l in left:
                if not l in right:
                    equal = False
        if equal:
            for r in right:
                if not r in left:
                    equal = False
    if not equal:
        return ['Comparing lists:',
                '   vals: %s != %s' % (left, right)]

Upvotes: 2

Views: 3912

Answers (2)

Sergei Voronezhskii
Sergei Voronezhskii

Reputation: 2362

I found easiest way to combinate py.test & pyhamcrest. In your example it is easy to use contains_inanyorder matcher:

from hamcrest import assert_that, contains_inanyorder
    
def test_first():
    assert_that(['a', 'b', 'c'], contains_inanyorder('b', 'a', 'c'))

Upvotes: 3

Milind Benjamin
Milind Benjamin

Reputation: 29

You could use a python set

assert set(['a', 'b', 'c']) == set(['b', 'a', 'c'])

This will return true

Upvotes: 2

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