PyTest assertions

You have probably seen how PyTest reports errors:

def test_make_empty_file():
    name = "/tmp/empty_test"
    make_empty_file(name)
    with open(name, "r") as fp:
    > assert not fp.read()
    E assert not 'hello'
    E + where 'hello' = ()
    E      +  where = .read

But do you know how it does it? And have you ever seen the error like

assertion failed, but when it was re-run for printing intermediate values, it did not fail.

I do really recommend reading this article http://pybites.blogspot.com/2011/07/behind-scenes-of-pytests-new-assertion.html

Comments

[Jason C. McDonald]

Hi Konstatin,

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