Robert Collins added the comment:
Future direction: hamcrest style matchers. You can read more about them in the
context of unittest
https://rbtcollins.wordpress.com/2010/05/10/maintainable-pyunit-test-suites/
and http://testtools.readthedocs.io/en/latest/for-test-authors.html#matchers -
sorry about the formatting in the blog post, wordpress changed theme details
some time after I wrote the post and it now renders horribly :(.
w.r.t. error messages, a regular function that raises AssertionError with a
nice message will be precisely as usable.
def assert_math_isclose(first, second, rel_tol=1e-09, abs_tol=0.0, msg=None):
if math.isclose(first, second, rel_tol=rel_tol, abs_tol=abs_tol):
return
standardMsg = ('%s != %s with relative tolerance of %.3g'
' and absolute tolerance of %.3g' % (safe_repr(first),
safe_repr(second),
rel_tol,
abs_tol))
if msg:
raise AssertionError("{} : {}".format(standardMsg, msg))
else:
raise AssertionError(standardMsg)
The reason I'm pushing back on adding methods to TestCase is that every one we
add collides with some number of subclasses out in the wild: the TestCase class
has multiple distinct APIs in the same namespace - and thats very poor for
maintaining compatibility.
Long term I want to have entirely separate interfaces for these things, but
thats even more radical an overhaul than adding matchers as a stock facility,
and I don't currently have a planned timeline for starting on that.
All of that said, I see that this isn't the same as assertAlmostEqual in
mathematical terms - but in /user/ terms I think it is. So why can't we make
assertAlmostEqual be this? Just add the extra parameter needed with a default
value and change the implementation?
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