Execute command from behave acceptance test

sample.feature

Feature: Tracing

  Scenario Outline: Generating a two column CSV
    When I execute: my_fictional_command input1.xml input2.xml --header=COL1;COL2
    Then the generated csv with <COL1> should map to <COL2>

  Examples: COL1 maps to COL2
        | REQ_ID| RELATED_ID |
        | COL1| COL2 |
        | A | 1 |
        | B | 2 |
        | C | 3 |

sample.py

from behave import *

import subprocess
from subprocess import CalledProcessError, PIPE


@when(u'I execute: {command}')
def step_impl(context, command):
    params = command.split()
    try:
        p = subprocess.Popen(params, stdout=PIPE, stderr=PIPE)
        out, err = p.communicate()
        context.stdout_capture.write(out)
        context.stdout_capture.write(err)
    except CalledProcessError as e:
        context.exception = e

@then(u'the generated csv with {col1} should map to {col2}')
def step_impl(context, col1, col2):
    # example for a two column csv file
    row_expression = re.compile("(.+);(.+)*")
    valid = False
    current_position = context.stdout_capture.tell()
    context.stdout_capture.seek(0)
    lines = [line for line in context.stdout_capture]
    context.stdout_capture.seek(current_position)
    for line in lines:
        if line.find(req_id) > -1:
            result = row_expression.match(line)
            assert result.group(1) == col1
            col2_values = result.group(2).split(" ")
            assert col2 in col2_values
            valid = True
            break
    assert valid