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pythonlistdictionaryassert

Trying to create assert error not working?

I'm making a very basic code that will check if the list in the dictionary length is greater than the integer in the other key of the dictionary.

For example, if I had:

d = {'lst': [1,2,3,4,5] , 'compare': 5}

Would be fine, because the max number of values (or length) of the list can be 5 (less than or equal to is fine).

This on the other hand should throw an assertion error:

d = {'lst': [1,2,3,4,5,6] , 'compare': 5}

because the length of the list in the key 'lst' > 'compare'.

Here's what I tried:

if len(d['lst']) > d['compare']:
    assert 'Queue is larger than max capacity'
else:
    pass

I'm brand new to using 'assert', so I'm likely using this wrong. If anyone could give me a hand it would be much appreciated!

Solution

  • The assert statement takes the condition as the first "argument". No if statement is required.

    assert len(d['lst'] <= d['compare']), "Queue is larger than max capacity"

    If the condition is false, an AssertionError (which includes the optional second argument) is raised. Otherwise, nothing happens.

    Think of assert foo, bar as a shortcut for

    # assert foo, bar
if foo:
    raise AssertionError(bar)