2013-07-01 Unit test, what a relief ?
To be honest, I hesitated. French, English, I was pissed off by own coding (I speak French in that case) but saved by a unit test...
Function signature are a bit tricky in python because this definition does not exist. There is only one function and you have to tweak around the parameters' type. So... this is an example of a case where unit tests were useful to me.
def function_nobody(input) :
if isinstance (input, list) :
for line in list :
# ....
elif isinstance (input ,str) :
with open(input, "r", encoding="utf8") as f :
for line in f :
# ...
So basically, the previous function accepts a file or a list. But I
wanted it to be more generic and to accept iterators:
import collections
def function_nobody(input) :
if isinstance (input, list) or isinstance (file, collections.Iterable) :
for line in list :
# ....
elif isinstance (input ,str) :
with open(input, "r", encoding="utf8") as f :
for line in f :
# ...
I added isinstance (file, collections.Iterable). But a string falls under
that condition which made the second case useless. But because I wrote
unit tests, I was able to catch my mistake. I just reverted the two tests:
import collections
def function_nobody(input) :
if isinstance (input ,str) :
with open(input, "r", encoding="utf8") as f :
for line in f :
# ...
elif isinstance (input, list) or isinstance (file, collections.Iterable) :
for line in list :
# ....
And it worked. I confess I did not lose two much time and I would not have lost
any even without unit tests because I would not know my failure.
However, I don't want to guess how much crazyness
I could have gone through if one of my scripts fails because of that a month,
two, three months later. How could I guess it is because of that...
Please do unit testing... Ok, it is late, my style might be overdramatic. But, please remember this when it is your time to experience one of these overdramatic scenarii. (I used the latin plural for scenario, don't know if it works in English).
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Xavier Dupré
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