Python 3 Gotchas

hasattr('xyz', '__iter__')  # False in Python 2

from pytest import raises
with raises(NameError):
    xrange(10)
with raises(NameError):
    basestring

bytes

# TypeError: string argument expected, got 'bytes'
import io
io.BytesIO  # Use BytesIO instead of StringIO

from pytest import raises
with raises(ImportError):
    import cStringIO
with raises(ImportError):
    import StringIO

from six import StringIO
from pytest import raises
with raises(AttributeError):
    StringIO().reset
StringIO().seek(0)