[Python-Dev] r87389 - in python/branches/py3k: Doc/library/unittest.rst Lib/unittest/case.py Misc/NEWS (original) (raw)

Guido van Rossum guido at python.org
Sun Dec 19 05:23:49 CET 2010

I may be unique, but I fear there is no great answer. On the one hand I almost always code it as e.g. assertEqual(actual, expected), which matches my preference for e.g. "if x == 5:" rather than "if 5 == x:". On the other hand in those assert* functions that show a nice diff of two lists, when reading such a diff my expectation is that "old, new" corresponds to "expected, actual". Which then freaks me out until I realize that I coded it as "actual, expected"... And yet "expected, actual" still looks weird to me. :-(

On Sat, Dec 18, 2010 at 2:46 PM, Terry Reedy <tjreedy at udel.edu> wrote:

On 12/18/2010 3:48 PM, Antoine Pitrou wrote:

On Sat, 18 Dec 2010 21:00:04 +0100 (CET) ezio.melotti<python-checkins at python.org>  wrote:

Author: ezio.melotti Date: Sat Dec 18 21:00:04 2010 New Revision: 87389 Log: #10573: use actual/expected consistently in unittest methods. Change was requested by M. Foord and R. Hettinger (and G.Brandl for b2). IMHO, this should be reverted. The API currently doesn't treat these arguments differently, so they should really be labeled "first" and "second". Otherwise, the user will wrongly assume that the signature is asymmetric and that they should be careful about which order they pass the arguments in. The error report on assert failure is often asymmetrical ;=). From Michael's post: "This is particularly relevant for the methods that produce 'diffed' output on failure - as the order determines whether mismatched items are missing from the expected or additional to the expected." This change struck me as a nice bit of polishing. -- Terry Jan Reedy

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-- --Guido van Rossum (python.org/~guido)

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