I will show how to create test automation with ddt and python, with code clean and adaptable in Real Project:

By using the data-driven testing approach, we can use a single test to verify different
sets of test cases or test data by driving the test with input and expected values from
an external data source instead of using the hardcoded values every time a test is run.

The ddt library provides the ability to parameterize the test cases written using the
unittest library in Python. We can provide a set of data using ddt to a test case for
data-driven tests.
The ddt library provides a set of class and method decorators that we can use to
create data-driven tests.

 Unmesh Gundecha - A practical guide on automated web testing with Selenium using Python.

 I will show how to create test automation with ddt and python, with code clean and adaptable in Real Project:

 1. Step - Install ddt pack:
We can download and install ddt using the following command line in shell or cmd windows:
pip install ddt
  
Home Page: https://github.com/txels/ddt

 2. Step - Reading values from CSV:
We will use the previous test case and move the data that we supplied to
the @data decorator into a separate CSV file called login_password_ok.csv instead of
keeping it in the script. This data will be stored in a tabular format as shown
in the following screenshot:

3. Install the TestLink in localhost:

Follow the video below:
https://www.youtube.com/watch?v=BaOxsJOpk30

4. Step - Create the users in TestLink :

Follow the video below:

Link this video on youtube.

5. Step - Creating the code:

5.1- Now let's go create two files in python:

- login_test.py

- variables_url_test.py - Will contain data that can change at any time.

5.1.1 Create file variables_url_test.py and insert data below:

LOGIN_PAGE = "/login.php?note=expired"
BASE_URL = "http://localhost//testlink-1.9.13"
MAIN_MENU = "/lib/general/navBar.php?tproject_id=0&tplan_id=0&updateMainPage=1"
LOGOUT_PAGE = "/logout.php"
LOGIN_PASS= "C:\\xxx\\xxx\\xxx\\xxx\\data\\login_password_ok.csv"
TOP_TEXT_MAIN_PAGE = "TestLink 1.9.13 (Stormbringer)"
XPATH_TOP_TEXT_MAIN_PAGE = "/html/body/div[2]/span[3]"
DELAY_FAST = 3

5.1.1 Create file login_test.py and insert data below:

"""
Author: Reinaldo Mateus R J, Test version: 0.1
Fist Step - Imports modules, in Python code in one module gains access to the code in another module by
    the process of importing.
Second Step - create function get_data in csv file.
Third Step - create class and function specific for test.
"""

import csv, unittest, time
from ddt import ddt, data, unpack
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.ui import WebDriverWait
from variables_test import *


def get_data(file_name):
    # create an empty list to store rows
    rows = []
    # open the CSV file
    print file_name
    data_file = open(file_name, "rb")
    # create a CSV Reader from CSV file
    reader = csv.reader(data_file)
    # skip the headers
    next(reader, None)
    # add rows from reader to list
    for row in reader:
         rows.append(row)
    return rows

# DDT consists of a class decorator @ddt (for your TestCase subclass)
@ddt
class LoginTestClass(unittest.TestCase):

    def setUp(self):
        # create a new Firefox session
        self.driver = webdriver.Firefox()
        self.driver.implicitly_wait(10)
        self.driver.maximize_window()
        # url base of website
        self.base_url = BASE_URL

    # Read the users in rows, and Passing variables tl_login,tl_password,user_type to function test_run.
    @data(*get_data(LOGIN_PASS))
    # will automatically unpack tuples and lists into multiple arguments, and dictionaries into multiple
    # keyword arguments.
    @unpack
    def test_run(self,tl_login,tl_password,user_type):

        wait = WebDriverWait(self.driver, 90)
        # Try three times if fail.
        for i in range(3):
            try:
                self.driver.get(self.base_url+ LOGIN_PAGE)
                elem = wait.until(lambda driver: driver.find_element_by_name("tl_login"))
                # Send user name in tl_login field
                elem.send_keys(tl_login)
                # Next we are sending keys, this is similar to entering keys using your keyboard.
                elem.send_keys(Keys.RETURN)
                elem = self.driver.find_element_by_name("tl_password")
                # Send password in tl_password field
                elem.send_keys(tl_password)
                # This is similar to entering keys using your keyboard.
                elem.send_keys(Keys.RETURN)
                time.sleep(DELAY_FAST)
                # timeout five seconds
                time.sleep(DELAY_FAST)
                self.driver.get(self.base_url+ MAIN_MENU)
                print "Test: ", tl_login, tl_password, user_type
                time.sleep(DELAY_FAST)
                confirm = wait.until(lambda driver: driver.find_element_by_xpath\
                    ("/html/body/div[2]/span[contains(text(),'"+user_type+"')]" ))
                print  confirm.text
                elem_test = str(confirm.text)
                time.sleep(DELAY_FAST)
                # split text in two words in the string.
                elem_test = elem_test.split(" ", 1)
                time.sleep(DELAY_FAST)
                print "Tag value: " + str(elem_test)
                # compare second word with user_type
                if elem_test[1] == "["+user_type+"]":
                    if (self.driver.find_element_by_xpath(XPATH_TOP_TEXT_MAIN_PAGE)):
                        # Test - compare text expected with XPATH_TOP_TEXT_MAIN_PAGE in browser.
                        self.assertTrue((self.driver.find_element_by_xpath(XPATH_TOP_TEXT_MAIN_PAGE).text\
                                         == TOP_TEXT_MAIN_PAGE))
                        print "Test User " +user_type+ " Passed with success!", tl_login, tl_password, user_type
                        break
                    else:
                        # Inform if not found the field expected.
                        time.sleep(10)
                        # Test - compare text expected with XPATH_TOP_TEXT_MAIN_PAGE in browser.
                        self.assertTrue((self.driver.find_element_by_xpath(XPATH_TOP_TEXT_MAIN_PAGE).text\
                                         == TOP_TEXT_MAIN_PAGE))
                        print "Element Xpath not found: ", tl_login, tl_password, user_type

            except:
                pass
                print "Failed!", tl_login, tl_password, user_type
                print "Failed attempts: ", i
                time.sleep(7)
            # Logout this web application
            self.driver.get(self.base_url+ LOGOUT_PAGE)

    def tearDown(self):
            # close the browser window
            self.driver.quit()

From basic mode we finished our tests, but not the testing activity is carried out to find the defects in the code & improve the quality of software application. Testing of application can be carried out in two different ways, Positive testing and Negative testing. Keep in mind that both positive and negative testing is equally important for effective testing which help to improve quality of software.


Negative Test scenarios:
Login and Password wrong, should not accept.
Login ok and Password wrong, should not accept.
Login wrong and Password ok, should not accept.
Password textbox should not exceeds more than 20 characters
Password textbox should not accept special characters.


Now we will expand our project to other operating systems in part two:
http://www.vidadetestador.com/2015/09/i-will-show-how-to-create-test_21.html