Defect cascading can be observed when one of the defects is not fixed or traced in the software application; it may result in other defects or shortcomings in the next stages.
If the Master defect is not identified, there can be further several defects that can spread across an application’s later stages, making it difficult to explore hidden defects thereby stopping the release of application unless all the defects are tracked and fixed.
Let me explain you with an example.
i) An authentication module is developed by a developer where a valid user can register into the application using either his email address or mobile number. If the user has worked in the code where registration is done with his email address, he has missed inserting a valid user’s mobile number into the database where the user’s information is saved into USER_REG table, and released the module to testers.
Forget Password link that requires email address which may send us a link that will allow the user to enter a new password. An additional layer of security is applied in order to protect the digital identity of the end-user, in the form of One-Time Password (OTP) is sent to the user’s registered mobile. If a registered mobile number is not inserted into USER_REG table, OTP will not reach to end-user. This will be another defect that will get uncovered.
ii) A Directory application is designed by a developer, wherein mobile numbers entered are national or international depending on the company’s registered geographical location. If a developer has not worked properly on the conditions to identify country code entered by end-user and country name corresponding to country code from COUNTRY_MASTER table.
When the call detail records that contain numbers from national, as well as international numbers uploaded into the system, in case of international numbers, it will not identify the name of the country of the telephone number of the customer’s company. The country of the customer’s company will not get displayed will be the first defect and further CUSTOMER_MASTER table will not able to identify country name thereby could not display customer’s country into search company based on country, which is another defect.
iii) An online cab services where user can be identified by his/her mobile number, he can book his pickup as well as drop locations. He can enter these details manually and can use this service; in this application integration of locations with Google map is not mapped by a developer and released for testing.
Entered locations like pickup and drop may get entered by the user, but the auto-complete address form will not function as desired if the user starts entering the location name. The application will not be user friendly where the user can quickly select a location from the drop-down list in pick up as well as drop location. Further locating an address by the cab driver will be another defect that gets uncovered.
Defect cascading is defects that are encountered by software testers, which further uncover another defect in the system while integration testing takes place. In order to locate defects that are primary which may further realize other defects in the application. Software testers should think and design use cases and scenarios that make sure those requirements are met while testing an application.
There should be transparency between developers and testers which should inform in the release, how much feature or requirements has been covered by his/her code, and what may affect if some functionality is not accomplished. A tester may log the bug/defect in the bug management system until code fulfills the feature functionality.
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