Functional and Usability Defects

What is meant by functional defects and usability defects in general? Give example.

Questions by girishchandra

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kurtz182  

  • Member Since Nov-2009 | Dec 14th, 2009


Functional testing refers to tests that verify a specific action or function of an application. Functional testing is performed by testers. Usability testing is a technique used to evaluate a product by testing it on users.  For example, when a tester finds that a text box is not validating properly, he has discovered a functional defect.  When a user doesn't understand a validation message because it uses technical jargon, this would be considered a usability defect.

It is a good idea to differentiate where defects originate in order to more practically assess a defect's Severity and Priority and many quality managment systems include a "Where found" field that helps identify the source of a defect as being functional (found by tester) or usability (found by end-user). 

Some software test teams have extended the definition of usability defect to include any defect that describes a lack of intuitiveness when using an application.   

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Consider Login window as an example

Functionality Defect:

assume that you have given valid user name, invalid password and clicked on Login Button, in return if application has accepted you user name and password, and Main window is displayed

Then this is a functionality defect.

Usability Defects :

assume that you have given valid user name, invalid password and clicked on Login Button, in return if application has generated a validation message stating "Please enter valid user name" instead of "Please enter valid Password"

Then this is a Usability Defect.

kumarsingh

  • Apr 20th, 2009
 

Functional Defects:
The defects raised taking functionality into account.
Ex: Booking the train ticket: User should able to book the tickets with valid
information


Usability Defects:
Defects raised keeping the how good the user can use the system
Ex: Booking the train ticket: During the booking how system guides us to book
the tickets without any issues..


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Hi

Functional Defects: Defects related to the functionality of an application

Ex: Consider a register page

    

      Registration Page

 

User Name :

 

password :          



Observe there is no login/submit button to enter into the application, so this is called functiional issues.

Usability Issues: Issues related to usability of the application ie how easily user will understood about the application and how cachy it is.

Ex: Consider the same example above, the word password doesn't start with capital letter, this will come under usability issues.


Srinivas

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Suppose if there is 2 Drop down list box (Country & State)in the form

Functional Defects: On Page load the application should load the Country items in the form, after selecting the country in the list, it should reload the page and the corresponding State should loaded and displayed in the State drop list box. if it is not loaded/displayed means it is Functional Defect.

Usability Defects: If the user changed the Countries and looks for the corresponding state, if the drop down list unable to load again the State list. its a Functional and Usability Defect.

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If the application is not behaving in the way as the requirements document suggests then it is considered as a functional defect. 
For example in a website, say a nokia website, if the spelling is Nokie, then it is a usability defect, which may not be listed in the requirement document but can be logged by the tester because of hs common sense. Also in order to log the usability defects the testers need not have specific test cases. They can log them while playing with the system.

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Functional defect: If you given a login form having username and password,
and if you give the valid user name and password but it wont accepts means it is
a functional defect.


Usability defect: The usability is how the application is user friendly to
the customer. It depends on the front page of the application. It should be
understandable to the customer.  If the proper buttons or fields are not
accessable by the customer is usability defect.


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ashishks

  • Aug 25th, 2009
 

Functionality Defects: If anything is not working as per requirement, then it is a functional defect.

Usability Defects: Any decrepencies in the look and feel of application is considered as usability defect.

E.g. Consider an requirement: 
        Upon clicking "Register" button(color of button is red and in rounded shape), application will redirect to homepage of the application.

Functional Defect: If upon clicking "Register" button, application is directed to login page, instead of homepage, then it is a functional defect.

Usability Defect: If label of the button is displayed as "regster" instead of "Register" and color is not "red", then this will be a usability defect.


 

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Functional Defect : If software is not working as per requirement specified.

Example:
Requiremnet:After successful login homepage should be logged in.
Funtional Testing test case:
Verify that when correct username and password is entered homepage is displayed.
Expected Result : Home page should be displayed.
Actual Result: Error message is prompted "Page cannot be displayed".
Usability Defect : When a user does not find a software product understandable, easy to learn, easy to operate and attractive.

Example:
Usability Testing test case:
Verify that homepage should have a content in Japanese Language.
Expected Result : Home page have a content in Japanese Language.
Actual Result: Home page have a content in English Language

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rahulskin

  • Sep 17th, 2009
 

Functional Defect:- If the functionality of the application is not working as per the requirement specification, it is functionality defect.
e.g. For calculator application Requirement is 1+1 = 2.
But the application is displaying 1+1=0.
It is functionality defect.

Usability Defect:- If the application is not easy to use, it is hard to use.  User interface should be proper and easy to use to the user.
e.g. User interface should be proper.  Easy to use.

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Functional testing refers to tests that verify a specific action or function of an application. Functional testing is performed by testers. Usability testing is a technique used to evaluate a product by testing it on users.  For example, when a tester finds that a text box is not validating properly, he has discovered a functional defect.  When a user doesn't understand a validation message because it uses technical jargon, this would be considered a usability defect.

It is a good idea to differentiate where defects originate in order to more practically assess a defect's Severity and Priority and many quality managment systems include a "Where found" field that helps identify the source of a defect as being functional (found by tester) or usability (found by end-user). 

Some software test teams have extended the definition of usability defect to include any defect that describes a lack of intuitiveness when using an application.   

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kk01041883

  • Jan 17th, 2010
 

Funcational defects

If the application behaviour does not obeys the functional specification then that is a functional issue.

e.g When you are trying to shut down your system, the system restart functionality is initiated instead of Shut down then this is a funcational issue.

Usability issue
Usability issue is an issue which has no impact on the funtional behaviour of the application.

e.g Tool tip for an icon or field is displayed incorrectly or tab order is not working properly or field's caption is not displaying properly or label text is turncated for fields in the application and so on....

Regards,
Kannan.

Functionality testing: While testing, if test engineer found any diffrence between customer expected result and  actual result is said to be Functionaluty bug.

Usability Bug: The usability bug means, if end user requires some other color or button's in the applcaition if some thing is appearing diffrence then it is said to be as Usability bug.

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