On Sun, Mar 18 2018, Shawn Brown wrote:
> Unfortunately, this does not solve my usecase. I'm trying to handle cases
> where the following statement would pass:
>
> assert myfunc(failing_input) == False
>
> But where this next statement would fail using my custom report:
>
> assert myfunc(failing_input)
>
> Calling myfunc() needs to return True or False (or at least Truthy or
> Falsy)--this is locked-in behavior.
I'm not sure if this is compatible with Python's semantics really. If I
understand correctly you're asking for a full-on macro implementation on
Python or something. Which in theory you could do with an AST
NodeVisitor, but really Python isn't made for this -- sounds like you'd
enjoy lisp! ;-)
The best thing I can suggest is to make use of the::
assert myfunc(failing_input), repr(myfunc(failing_input()))
functionality to also get a custom error message. Here your myfunc()
whould have to return some object which both implements __bool__ as well
as __repr__ I guess.
Maybe there's a feature request in here for something like this::
class Foo:
def __bool__(self):
return False
def __repr__(self):
return 'multiline\nstring'
assert Foo()
To actually show the repr in the error message, which it currently
doesn't. I'd like to know what other people think of such a feature
though, and haven't thought through all the implications yet. But I'm
curious, would something like that solve your case?
Cheers,
Floris
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