[osflash] Design By Contract on ActionScript 2

[Bernd Will]

Hello everybody,

 

don't know if you know Python's doctest feature. There you can embed tests
right into the classes instead of coding xxxTest classes all the way.

In Python you write down the header of the class, then start a comment tag
and put numerous tests together with the expected results, then you close
the comment. When done, you start writing the method.

It is all in one place, no huddling no searching, just scroll up to the top
of the method and you have the tests right before your nose.

 

Below is a short Python snippet demonstrating this nice feature.

In Python comments are enclosed by  """ [.] """" triple signs.

Every test starts with the >>> sign, which is the call of the function.

Every test is  written down as being called and after the call, you find the
awaited result.
This idea can't be transferred to ActionScript, since Python is a Basic like
interpreted language putting back results after every command.

But the idea of putting tests and results in one place side by side with the
code IMHO is worth thinking about as a nice feature.

 

 

def factorial(n):
    """Return the factorial of n, an exact integer >= 0.
 
    If the result is small enough to fit in an int, return an int.
    Else return a long. Here are the tests:
 
    >>> [factorial(n) for n in range(6)]
    [1, 1, 2, 6, 24, 120]
    >>> [factorial(long(n)) for n in range(6)]
    [1, 1, 2, 6, 24, 120]
    >>> factorial(30)
    265252859812191058636308480000000L
    >>> factorial(30L)
    265252859812191058636308480000000L
    >>> factorial(-1)
    Traceback (most recent call last):
        ...
    ValueError: n must be >= 0
 
    Factorials of floats are OK, but the float must be an exact integer:
    >>> factorial(30.1)
    Traceback (most recent call last):
        ...
    ValueError: n must be exact integer
    >>> factorial(30.0)
    265252859812191058636308480000000L
 
    It must also not be ridiculously large:
    >>> factorial(1e100)
    Traceback (most recent call last):
        ...
    OverflowError: n too large
    """
    import math
    if not n >= 0:
        raise ValueError("n must be >= 0")
    if math.floor(n) != n:
        raise ValueError("n must be exact integer")
    if n+1 == n:  # catch a value like 1e300
        raise OverflowError("n too large")
    result = 1
    factor = 2
    while factor <= n:
        result *= factor
        factor += 1
    return result
 
 
 
def _test():
    import doctest
    doctest.testmod()
 
 
 
if __name__ == "__main__":
    _test()

 

 

Regards

Bernd

 

  _____  

Von: osflash-bounces at osflash.org [mailto:osflash-bounces at osflash.org] Im
Auftrag von Michael Forrest
Gesendet: Samstag, 7. Oktober 2006 11:27
An: Open Source Flash Mailing List
Betreff: Re: [osflash] Design By Contract on ActionScript 2

 

Getting some unit testing working would be a start. AS2Lib has testing
libraries and the AS2Ant tasks give a way of running them from ANT scripts
as part of a build process. http://www.simonwacker.com
<http://www.simonwacker.com> 



On 10/5/06, Marcelo de Moraes Serpa <celoserpa at gmail.com> wrote:

Is there any tool for AS2 that allows me to implement the DBC methodology?

Cheers,

Marceo.

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