Cost to Fix the Bug

A Bug can occur in any of the stages of a Software Development Life Cycle.Early the Bug is found in SDLC, relatively easy is to fix it, less is the time required to fix it, less is the complexity to fix it & ultimately less is the cost to fix it.

As we move further in the Software Development Life Cycle, more cost it takes to fix the Bug.

The Cost to fix the Bug during Testing phase or after release (i.e. Maintenance Phase ) is much higher than the Cost to fix the Bug during earlier stages.

Below image shows the graphical representation of the increasing cost of bug fixing with the progress in development stages. 

What is Whitebox Testing, Blackbox Testing & Graybox Testing ?

White-box Testing -

• To perform White-box Testing, the programming knowledge is essential.
• Tester should have access to the code & the internal data structures and algorithms.
• In White-box Testing Tester checks for correctness and completeness of the application through code.
• Below are some of the White-box Testing types,

1. Mutation testing
2. Code coverage
3. API Testing

Black-box Testing -

• Black-box Testing is a testing technique in which the knowledge of internal structure/code is not needed.
• Black-box Testing is carried out by executing the application and access to code is not required.
• Black-box Testing is applicable for Unit Testing, Functional Testing, Integration Testing, System Testing, Acceptance Testing.
• Tester should know 'What a system is supposed to do', 'How and what it does internally' is not necessary to know for Black-box testing.

Gray-box Testing -

• Gray-box Testing is a testing technique in which a Tester performs Black-box Testing with knowledge of internal structure of the application.