Selenium using python: Logging Exception In Selenium

What is an Exception ?

When inputs to function are invalid or pre-condition are not meet an error is raised know as Exception.
To know more about exception we will see ValueError & DivideByZero exception in python
and later on NoSuchElementFound in selenium

Exception in Python

Example 1--ValueError
For the code below if the user enter string or alpha-numeric an exception is raised.

age = int(input("Enter your age"))

Example 2--DivideByZero

num = int(input("Enter a number greater than 0"))
print (10/num)

How to handle Exceptions ?

Exception can be caught using TRY & EXCEPT block statements.
Note: Exception should not be used as part of the normal code,but only for exceptional situations.
Only catch exception that you know to handle.

Solution for Example 1--Handling ValueError

#save the below code in valueError.py
while True:
    try:
        age = int(input("Enter your age: "))
        print("Your age is %d"%age)
        break
    except ValueError as ve:
        print ("{} .Enter a number only".format(ve))

Output

Solution for Example 2--Handling DivideByZeror

#save the below code in divideZero.py
while True:
    try:
        number = int(input("Enter a number: "))
        print (10/number)
        break
    except ValueError as ve:
        print ("{} .Enter a number only".format(ve))

    except ZeroDivisionError as zde:

        print("{} .Enter a number ".format(zde))

    except:

        print ("unknown exception")

Output

Exception in Selenium

NoSuchElementFound--- exception is raised when element to be located by the following methods

fails

find_element_by_id
find_element_by_name
find_element_by_tag_name
find_element_by_css_selector
find_element_by_xpath
find_element_by_link_text
find_element_by_partial_link_text
find_element_by_class_name

Example 1--NoSuchElementFound

import unittest
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.common.by import By

class Youtube(unittest.TestCase):

    def setUp(self):

        self.browser = webdriver.Firefox()
        self.browser.get("http://www.youtube.com")

    def tearDown(self):

        self.browser.quit()

    def test_search(self):

        browser = self.browser
        browser.find_element(By.ID,"1masthead-search-term")
        browser.send_keys("git tutorials")
        browser.send_keys(Keys.RETURN)

if __name__ == "__main__":

    unittest.main(warnings='ignore')

Handling "NoSuchElementFound" exception

import unittest
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.common.exceptions import NoSuchElementException
from selenium.webdriver.common.by import By

class YoutubeSearch(unittest.TestCase):

    def setUp(self):

        self.browser = webdriver.Firefox()
        self.browser.get("http://www.youtube.com")
        
    def tearDown(self):
        
        self.browser.save_screenshot('YoutubeSearchTest.png')
        self.browser.quit()
        
    def is_element_present(self,how,what):

        try:
            self.browser.find_element(by=how,value=what)
        except NoSuchElementException:
            return False
        return True

    def test_youtube(self):
        
        self.assertIn("YouTube",self.browser.title)
        self.assertTrue(self.is_element_present(By.ID,"1masthead-search-term"))
        searchElement = self.browser.find_element_by_id("1masthead-search-term")
        searchElement.send_keys("python tutorials")
        searchElement.send_keys(Keys.RETURN)

if __name__ == "__main__":

    unittest.main(exit=False,warnings = 'ignore')

Output in IDLE

Output in Window Command-line

What is Logging ?

Logging is a standard python Module.It record or track the events during the execution of a Application.Logging message are displayed or stored using Logging function and logging Levels.

Developers use it for Debugging ie....fault investigation.
System Admin use it for Monitoring ie... resources are used effectively.
Help Desk use it for answering client about the problem and about the Patch or workaround to be applied.

Logging Functions

logging.debug('This function provides detailed information ')

logging.warning('Something unexpected happened')

logging.error('For storing exception traces')
logging.info('It is a confirmation that things are going according to plan')

logging.critical('The main action to be performed fails')

Logging Levels

Given below are logging levels in the increasing order of severity.Critical is the highest level and Info is the lowest level...ie if we configure the logs for WARNING our log file will contain logs of WARNING,ERROR & CRITICAL.The default log message are WARNING

DEBUG
INFO
WARNING
ERROR
CRITICAL

Creating a simple logger

Step 1: Import the logging Module

import logging

Step 2: Create a logger with a level of logs to be recorded

logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

Step 3: Create a Log-Handler

handler_warn = logging.FileHandler('warning_log.txt')
handler_warn.setLevel(logging.WARNING)

Step 4: Create For-matter for Log-Handlers

formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler_warn.setFormatter(formatter)

Step 5: Add the log-handler to the logger

logger.addHandler(handler_warn)

Example 1--Using the above steps we can write our first Logger, warning logs are found in 'warning_log.txt' and INFO logs in 'info_log.txt'

#Import the logging module
import logging

logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#Create a file handler
handler_warn = logging.FileHandler('warning_log.txt')
handler_warn.setLevel(logging.WARNING)

handler_info = logging.FileHandler('info_log.txt')
handler_info.setLevel(logging.INFO)

#create a logging format

formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler_warn.setFormatter(formatter)
handler_info.setFormatter(formatter)


#add the handler to the logger

logger.addHandler(handler_warn)
logger.addHandler(handler_info)


logger.info('Information')
logger.warning('warning')

Output
warning_log.txt

2014-12-29 19:02:15,217 - __main__ - WARNING - warning

info_log.txt

2014-12-29 19:02:15,217 - __main__ - INFO - Information
2014-12-29 19:02:15,217 - __main__ - WARNING - warning

Example 2--Handling Exception

#Import the logging module
import logging

#Create a logger
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#Create a log-handler
handler = logging.FileHandler('ex1_critical.txt')
handler.setLevel(logging.INFO)

#Format for logs
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)

#add the handler to the logger
logger.addHandler(handler)

def age():
    """Function Prompt the user for their age"""
    logger.info('Inside function age()')

    try:
        logger.info('In the try Block ')
        age = int(input("Enter your age"))
        logger.debug('Value of age is %s'%age)
        
    except ValueError as e:

        logger.critical('Invalid Input',exc_info=True)


if __name__ == "__main__":

    age()

Contents of ex1_critical.txt

2014-12-29 20:44:25,962 - __main__ - INFO - Inside function age()
2014-12-29 20:44:25,962 - __main__ - INFO - In the try Block 
2014-12-29 20:44:35,320 - __main__ - CRITICAL - Invalid Input
Traceback (most recent call last):
  File "D:/coursera/selenium/blog/post3/config.py", line 24, in age
    age = int(input("Enter your age"))
ValueError: invalid literal for int() with base 10: '1!'

Example 3--We will consider an Example where we have to

Navigate to www.youtube.com and Assert for the Title
locate the searchBox
Search for Python Tutorials

An exception can be raised if Invalid Locator to the searchBox is given(NoSuchElementException) or if the title for the Youtube Page in Test Script is Wrong(AssertionError)
Here were store the CRITICAL logs in a file called Youtube.txt and INFO logs are seen at the console.

Example 3.1 Handling--AssertionError CRITICAL logs ---found in-'Youtube.txt'

import unittest
import logging
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.common.exceptions import NoSuchElementException
from selenium.webdriver.common.by import By

#create a logger
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#create log-handlers
#I need the critical logs in a file called Youtube.txt
handler_critical = logging.FileHandler('Youtube.txt','w')
handler_critical.setLevel(logging.WARNING)
#I need all the logs above the INFO level on the console
handler_info = logging.StreamHandler()
handler_info.setLevel(logging.INFO)

#FORMATTERES
formatter = logging.Formatter('%(asctime)s - %(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler_critical.setFormatter(formatter)
handler_info.setFormatter(formatter)

#add the handlers
logger.addHandler(handler_info)
logger.addHandler(handler_critical)



class YoutubeSearch(unittest.TestCase):

    def setUp(self):

        logger.info("-----Starting setup------")
        self.browser = webdriver.Firefox()
        self.browser.get("http://www.youtube.com")
        logger.info("-----setup complete-----")
        
    def tearDown(self):
        logger.info("-----starting teardown------")
        self.browser.save_screenshot('YoutubeSearchTest.png')
        self.browser.quit()
        logger.info("----teardown complete-------")

        
    def test_youtube_search(self):
        
        logger.info("-----in the test------")

        try:
            self.assertIn("1YouTube",self.browser.title)
            searchElement = self.browser.find_element_by_id("masthead-search-term")
            
        except AssertionError:
            logger.critical('Browser element',exc_info=True)
            self.fail('Title not found')
        except NoSuchElementException:
            logger.critical('element for search box',exc_info=True)
            self.fail('SearchBox element not found')
        else:
            searchElement.send_keys("python tutorials")
            searchElement.send_keys(Keys.RETURN)
            logger.info("----test case complete----")
        


if __name__ == "__main__":

    unittest.main(exit=False,warnings = 'ignore')

Contents of Youtube.txt file

2014-12-30 17:31:38,342 - 2014-12-30 17:31:38,342 - __main__ - CRITICAL - Browser element
Traceback (most recent call last):
  File "D:\coursera\selenium\blog\post3\youtube_v1.py", line 52, in test_youtube_search
    self.assertIn("1YouTube",self.browser.title)
  File "C:\Python34\lib\unittest\case.py", line 1056, in assertIn
    self.fail(self._formatMessage(msg, standardMsg))
  File "C:\Python34\lib\unittest\case.py", line 642, in fail
    raise self.failureException(msg)
AssertionError: '1YouTube' not found in 'YouTube'

Example 3.2 Handling -- NoSuchElementException---CRITICAL logs ---found in-'Youtube.txt'

import unittest
import logging
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.common.exceptions import NoSuchElementException
from selenium.webdriver.common.by import By

#create a logger
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#create log-handlers
#I need the critical logs in a file called Youtube.txt
handler_critical = logging.FileHandler('Youtube.txt','w')
handler_critical.setLevel(logging.WARNING)
#I need all the logs above the INFO level on the console
handler_info = logging.StreamHandler()
handler_info.setLevel(logging.INFO)

#FORMATTERES
formatter = logging.Formatter('%(asctime)s - %(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler_critical.setFormatter(formatter)
handler_info.setFormatter(formatter)

#add the handlers
logger.addHandler(handler_info)
logger.addHandler(handler_critical)



class YoutubeSearch(unittest.TestCase):

    def setUp(self):

        logger.info("-----Starting setup------")
        self.browser = webdriver.Firefox()
        self.browser.get("http://www.youtube.com")
        logger.info("-----setup complete-----")
        
    def tearDown(self):
        logger.info("-----starting teardown------")
        self.browser.save_screenshot('YoutubeSearchTest.png')
        self.browser.quit()
        logger.info("----teardown complete-------")

        
    def test_youtube_search(self):
        
        logger.info("-----in the test------")

        try:
            self.assertIn("YouTube",self.browser.title)
            searchElement = self.browser.find_element_by_id("1masthead-search-term")
            
        except AssertionError:
            logger.critical('Browser element',exc_info=True)
            self.fail('Title not found')
        except NoSuchElementException:
            logger.critical('element for search box',exc_info=True)
            self.fail('SearchBox element not found')
        else:
            searchElement.send_keys("python tutorials")
            searchElement.send_keys(Keys.RETURN)
            logger.info("----test case complete----")
        


if __name__ == "__main__":

    unittest.main(exit=False,warnings = 'ignore')

Contents of Youtube.txt file

2014-12-30 17:31:38,342 - 2014-12-30 17:31:38,342 - __main__ - CRITICAL - Browser element
Traceback (most recent call last):
  File "D:\coursera\selenium\blog\post3\youtube_v1.py", line 52, in test_youtube_search
    self.assertIn("1YouTube",self.browser.title)
  File "C:\Python34\lib\unittest\case.py", line 1056, in assertIn
    self.fail(self._formatMessage(msg, standardMsg))
  File "C:\Python34\lib\unittest\case.py", line 642, in fail
    raise self.failureException(msg)
AssertionError: '1YouTube' not found in 'YouTube'
2014-12-30 17:40:42,573 - 2014-12-30 17:40:42,573 - __main__ - CRITICAL - element for search box
Traceback (most recent call last):
  File "D:\coursera\selenium\blog\post3\youtube_v1.py", line 53, in test_youtube_search
    searchElement = self.browser.find_element_by_id("1masthead-search-term")
  File "C:\Python34\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 206, in find_element_by_id
    return self.find_element(by=By.ID, value=id_)
  File "C:\Python34\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 662, in find_element
    {'using': by, 'value': value})['value']
  File "C:\Python34\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 173, in execute
    self.error_handler.check_response(response)
  File "C:\Python34\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 166, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: {"method":"id","selector":"1masthead-search-term"}
Stacktrace:
    at FirefoxDriver.prototype.findElementInternal_ (file:///C:/Users/DANIEL~1/AppData/Local/Temp/tmpsckt44ay/extensions/fxdriver@googlecode.com/components/driver-component.js:9641:26)
    at FirefoxDriver.prototype.findElement (file:///C:/Users/DANIEL~1/AppData/Local/Temp/tmpsckt44ay/extensions/fxdriver@googlecode.com/components/driver-component.js:9650:3)
    at DelayedCommand.prototype.executeInternal_/h (file:///C:/Users/DANIEL~1/AppData/Local/Temp/tmpsckt44ay/extensions/fxdriver@googlecode.com/components/command-processor.js:11635:16)
    at DelayedCommand.prototype.executeInternal_ (file:///C:/Users/DANIEL~1/AppData/Local/Temp/tmpsckt44ay/extensions/fxdriver@googlecode.com/components/command-processor.js:11640:7)
    at DelayedCommand.prototype.execute/< (file:///C:/Users/DANIEL~1/AppData/Local/Temp/tmpsckt44ay/extensions/fxdriver@googlecode.com/components/command-processor.js:11582:5)

Example 3.3 Finally the correct code

NOTE:Logging configuration can be placed in seperate logging.conf file

import unittest
import logging
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.common.exceptions import NoSuchElementException
from selenium.webdriver.common.by import By

#create a logger
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

#create log-handlers
#I need the critical logs in a file called Youtube.txt
handler_critical = logging.FileHandler('Youtube.txt','w')
handler_critical.setLevel(logging.WARNING)
#I need all the logs above the INFO level on the console
handler_info = logging.StreamHandler()
handler_info.setLevel(logging.INFO)

#FORMATTERES
formatter = logging.Formatter('%(asctime)s - %(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler_critical.setFormatter(formatter)
handler_info.setFormatter(formatter)

#add the handlers
logger.addHandler(handler_info)
logger.addHandler(handler_critical)



class YoutubeSearch(unittest.TestCase):

    def setUp(self):

        logger.info("-----Starting setup------")
        self.browser = webdriver.Firefox()
        self.browser.get("http://www.youtube.com")
        logger.info("-----setup complete-----")
        
    def tearDown(self):
        logger.info("-----starting teardown------")
        self.browser.save_screenshot('YoutubeSearchTest.png')
        self.browser.quit()
        logger.info("----teardown complete-------")

        
    def test_youtube_search(self):
        
        logger.info("-----in the test------")

        try:
            self.assertIn("YouTube",self.browser.title)
            searchElement = self.browser.find_element_by_id("masthead-search-term")
            
        except AssertionError:
            logger.critical('Browser element',exc_info=True)
            self.fail('Title not found')
        except NoSuchElementException:
            logger.critical('element for search box',exc_info=True)
            self.fail('SearchBox element not found')
        else:
            searchElement.send_keys("python tutorials")
            searchElement.send_keys(Keys.RETURN)
            logger.info("----test case complete----")
        


if __name__ == "__main__":

    unittest.main(exit=False,warnings = 'ignore')

Output

>>> ================================ RESTART ================================
>>> 
2014-12-30 17:15:11,070 - 2014-12-30 17:15:11,070 - __main__ - INFO - -----Starting setup------
2014-12-30 17:15:47,270 - 2014-12-30 17:15:47,270 - __main__ - INFO - -----setup complete-----
2014-12-30 17:15:47,333 - 2014-12-30 17:15:47,333 - __main__ - INFO - -----in the test------
2014-12-30 17:16:02,422 - 2014-12-30 17:16:02,422 - __main__ - INFO - ----test case complete----
2014-12-30 17:16:02,500 - 2014-12-30 17:16:02,500 - __main__ - INFO - -----starting teardown------
2014-12-30 17:16:07,919 - 2014-12-30 17:16:07,919 - __main__ - INFO - ----teardown complete-------
.
----------------------------------------------------------------------
Ran 1 test in 56.864s

OK
>>>

Selenium using python

Tuesday 30 December 2014

Logging Exception In Selenium

What is an Exception ?

How to handle Exceptions ?

What is Logging ?

Logging Functions

Logging Levels

Creating a simple logger

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