For this sample program
N = int(raw_input());
n = 0;
sum = 0;
while n<N:
sum += int(raw_input());
n+=1;
print sum;
I have a set of testcases, so I need a python program that invokes the above python program, gives input and should validate the output printed in the console.
In a Unix shell, this can be achieved by:
$ python program.py < in > out # Takes input from in and treats it as stdin.
# Your output goes to the out file.
$ diff -w out out_corr # Validate with a correct output set
You can do the same in Python like this
from subprocess import Popen, PIPE, STDOUT
f = open('in','r') # If you have multiple test-cases, store each
# input/correct output file in a list and iterate
# over this snippet.
corr = open('out_corr', 'r') # Correct outputs
cor_out = corr.read().split()
p = Popen(["python","program.py"], stdin=PIPE, stdout=PIPE)
out = p.communicate(input=f.read())[0]
out.split()
# Trivial - Validate by comparing the two lists element wise.
Picking up the separation thought, I would consider this:
def input_ints():
while True:
yield int(raw_input())
def sum_up(it, N=None):
sum = 0
for n, value in enumerate(it):
sum += int(raw_input());
if N is not None and n >= N: break
return sum
print sum
To use it, you can do
inp = input_ints()
N = inp.next()
print sum_up(inp, N)
To test it, you can do something like
inp = (1, 2, 3, 4, 5)
assert_equal(sum_up(inp), 15)
I wrote a testing framework (prego) that may be used for your issue::
from hamcrest import contains_string
from prego import TestCase, Task
class SampleTests(TestCase):
def test_output(self):
task = Task()
cmd = task.command('echo your_input | ./your_app.py')
task.assert_that(cmd.stdout.content,
contains_string('your_expected_output'))
Of course, prego provides more features than that.
Ordinarily, you'd want to structure your code in a different way, perhaps according to how Blender suggested in his comment. To answer your question, however, you can use the subprocess module to write a script that will call this script, and compare the output to an expected value.
In particular, look at the check_call method.
raw_input()s with parameters. Also, don't put semicolons at the end of each line. Python doesn't require them.raw_input()to get user input and feed it into your original function. It'll be easier if you separate the logic from the user interaction.