Sphinx Doctest: test the code without comparing the output.

[Luca Cerone]

> This makes no sense. If you ignore the output, the code could do ANYTHING 
> 
> and the test would still pass. Raise an exception? Pass. SyntaxError? 
> 
> Pass. Print "99 bottles of beer"? Pass.
> 

if you try the commands, you can see that the tests fail..
for example

.. doctest::

   >>> raise Exception("test")

will fail with this message: 

File "utils.rst", line 5, in default
Failed example:
    raise Exception("test")
Exception raised:
    Traceback (most recent call last):
      File "/usr/lib/python2.7/doctest.py", line 1289, in __run
        compileflags, 1) in test.globs
      File "<doctest default[0]>", line 1, in <module>
        raise Exception("test")
    Exception: test

So to me this seems OK.. "Print" will fail as well...

> 
> 
> I have sometimes written unit tests that just check whether a function 
> 
> actually is callable:
> 
> 
> 
> ignore = function(a, b, c)
> 
> 
> 
> but I've come to the conclusion that is just a waste of time, since there 
> 
> are dozens of other tests that will fail if function isn't callable. But 
> 
> if you insist, you could always use that technique in your doctests:
> 
> 
> 
> >>> ignore = function(a, b, c)
> 
> 
> If the function call raises, your doctest will fail, but if it returns 
> 
> something, anything, it will pass.
> 
> 

I understand your point, but now I am not writing unit tests to check the correctness of the code. I am only writing a tutorial and assuming that
the code is correct. What I have to be sure is that the code in the tutorial
can be executed correctly, and some commands print verbose output which can change.

It is not enough to write >>> ignore = function(a,b,c) won't work because the function still prints messages on screen and this causes the failure of the test...