On 2018-07-05 18:57, Steven D'Aprano wrote:
I have a function which returns a dict, and I want to use doctest to
ensure the documentation is correct. So I write a bunch of doctests:
def func(arg):
"""blah blah blah
>>> func(1)
{'a': 1, 'b': 2, 'c': 3}
"""
which is correct, *except* that dict keys have arbitrary order in the
versions of Python I'm using.
I have three ways of dealing with this. Which do you prefer?
1. Re-write the doctest to compare with another dict:
>>> actual = func(1)
>>> expected = {'a': 1, 'b': 2, 'c': 3}
>>> actual == expected
True
I don't like that because it obscures the clear relationship between
"call the function" -> "here's the output you get".
2. Use a pretty-printer function that cleverly sorts the keys before
printing:
>>> _ppr(func(1))
{'a': 1, 'b': 2, 'c': 3}
I don't like that, because the call to the pretty printer obscures the
call to the function.
3. I thought, "what a pity I can't move the pretty printer to the end od
the line, instead of the beginning, to reduce the emphasis on it". And
then I thought, yes I can!" and re-wrote the pretty printer to use the
__ror__ method instead:
>>> func(1) | _ppr
{'a': 1, 'b': 2, 'c': 3}
I think that's really clever. Is it too clever? How do you deal with
dicts in doctests?
(Ensuring that the dicts only have a single item is not feasible.)
What about sorting the items?
def func(arg):
"""blah blah blah
>>> sorted(func(1).items())
[('a', 1), ('b', 2), ('c', 3)]
"""
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