testing code

[Sharan Basappa]

On Friday, 6 July 2018 09:32:08 UTC+5:30, Cameron Simpson  wrote:
> On 05Jul2018 19:56, Sharan Basappa <sharan.basappa at gmail.com> wrote:
> >I have implemented my first program in python that uses ML to do some 
> >classification task. The whole code is in a single file currently.
> >It contains executable code as well as functions.
> 
> I presume when you write "executable code" you mean some kind of "main program" 
> that just runs when you run the .py file?
> 
> >At the end of the program, I have series of calls that is used to test my code.
> >Now, I would like to re-structure this to separate test code from the program.
> >As I have not done this in Python, I am a bit lost.
> >
> >Please let me know if the following understanding of mine is correct.
> >I need to put the program code in a separate file and organize every executable code in some form of function. If any code exists outside of function then it is not executable by importing.
> 
> This is not quite right. Because Python is a dynamic language, importing a file 
> actually runs it. That is how the functions etc get defined.
> 
> So what you need to do is arrange that your "series of calls that is used to 
> test my code" live in their own function, and that that function only gets run 
> if the file is directly run.
> 
> Fortunately, this is a very common, almost universal, requirement and there is 
> a standard idom for arranging it.
> 
> Support you have your code in the file "foo.py" (because I need a concrete 
> filename for the example). It might look like this at present:
> 
>   def func1(...):
> 
>   def func2(...):
> 
>   x = func1(...)
>   y = func2(...)
>   print(x + y)
> 
> i.e. some function definitions and then you testing code.
> 
> Now, you can write another file "foo_tests.py" which starts like this:
> 
>   import foo
>   ... run some tests of foo.func1, foo.func2 etc ...
> 
> The issue is that as written, foo.py will run your test calls during the 
> import.  Restructure foo.py like this:
> 
>   def main():
>       x = func1(...)
>       y = func2(...)
>       print(x + y)
> 
>   def func1(...):
> 
>   def func2(...):
> 
>   if __name__ == '__main__':
>       main()
> 
> This is very standard. When you run a python file directly the built in  
> __name__ variable contains the string "__main__". This tells you that you're 
> running it as a "main program" i.e. directly.
> 
> If you import the file instead, as from your planned testing file, the __name__ 
> variable will contain the string "foo" because that is the name of the module.
> 
> So that "main" function and the "if" at the bottom is standard Python 
> boilerplate code for what you're trying to do.
> 
> >Import this in my test program (file/module) and then initiate  calls present 
> >in the program.
> >If there is some simple example, it would help a lot.
> 
> Now you can do this part.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>

Cameron.

thanks. this is much more easier than I thought.