[issue27198] Adding an assertClose() method to unittest.TestCase

[Chris Barker]

Chris Barker added the comment:

Thanks Raymond.

Damn! I wrote a nice comprehensive note, and my browser lost it somehow :-(.

Here's a shorter version:

"FWIW, I find assertClose easy to misinterpret.  At first, it looks like an assertion that a file is closed."

sure -- we can find a new name -- I only used that because it's called "isclose" in the math module -- but no one's likely to think a math module function is about files...

"we don't need another way to do it"

Yes, we certainly do -- it was added to the math module (even though a large fraction of use cases would be testing), and something like this is in numpy, Boost, etc, and as the long debate about the PEP indicates -- it's not obvious how to do it -- I'd argue this is more necessary in unitest than most of the other asserts....

(and, sample size 1: a relatively new user offered to proofread the patch for me, and immediately said "hey this is great -- I've been needing this!"

Frankly, the objections to adding new aseert methods are really a critique of the unittest API -- it is clearly DESIGNED to have specialized asserts for many common use cases. So I think we should either:

Embrace the API and add useful asserts like this one.

or

Make a concerted effort (Primarily through documentation) to move toward a different API (or a different way to use the current one, anyway). Robert's posts about "matches" are a good start.

In the meantime, maybe the way to go with this is to add it to assertAlmostEqual -- it gives folks the functionality, makes it discoverable, and doesn't add a new name.

Any objections to that before I take the time to code that up?

-Chris

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<http://bugs.python.org/issue27198>
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