Difference between blackbox and whitebox tests

The key difference between black box testing and white box testing lies in their approach to examining software functionality.

Here's a breakdown to clarify:

Black Box Testing:

Black box testing, also known as behavioural testing, treats the software as a black box. Testers are concerned with the external behaviour and functionality without considering the internal code structure. Black box testers typically don't require in-depth knowledge of the software's internal code. They focus on requirements, specifications, and user stories.

Black box testing is useful for:

• System testing and user acceptance testing.
• Usability testing.
• Smoke testing and sanity testing.

Black box testing techniques are:

• Equivalence partitioning
• Boundary value analysis
• Error guessing and
• User scenario testing

These techniques focus on input values, expected outputs, and system behaviour under various conditions.

Advantages:

• Black box testing reflects how actual users interact with the software, identifying usability issues and ensuring an intuitive user experience.
• By testing against requirements and specifications, black box testing verifies if the software delivers the promised features and functionalities.
• Testers don't need to learn the code-base, making black box testing potentially faster to implement.
• Black box tests can often be automated using scripts or recording tools, streamlining the testing process.
• Since in-depth knowledge of the code isn't required, black box testing allows testers with a broader range of skill sets to participate.

Disadvantages:

• Black box testing doesn't develop into the internal workings of the code, potentially missing logic errors or edge cases not covered by user scenarios.
• Black box testing might struggle to identify complex bugs buried within the code's logic.
• Clear and well-defined requirements and specifications are crucial for effective black box testing.

White Box Testing:

White box testing, also known as structural testing, examines the software from the inside out. Testers have a deep understanding of the code structure, logic flow, and internal workings of the software. White box testers require a strong understanding of programming languages, code structure, and software design principles.

White box testing is useful for:

• Unit testing.
• Integration testing.
• Test-driven development.

White box testing techniques are: 

• Unit testing (testing individual modules)
• Code coverage analysis (ensuring all code paths are exercised), and
• Control flow testing (verifying logic under different conditions)

These techniques helps in development the code's functionality and implementation details.

Advantages:

• White box testing allows for very granular testing, ensuring code paths, logic branches, and error handling mechanisms are functioning correctly.
• By examining the code structure, white box testing can identify potential issues early in the development cycle.
• Focusing on code coverage and logic ensures the software is well-structured and functions as intended.
• When a bug is encountered, testers with knowledge of the code can pinpoint the root cause more easily.

Disadvantages:

• White box testing requires a significant investment of time and effort, especially for complex code-bases.
• Testers need a strong understanding of programming languages and software design principles.
• As the code evolves, white box tests might need to be frequently updated to maintain their effectiveness.
• White box testing might overlook usability issues that wouldn't be apparent from examining the code alone.