Black-box Testing

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Black-box testing is a technique to test software while ignoring its internal structure or code. You give test inputs and test the outputs of the software. You test how the software works, not how it is built. Black-box testing is based on software requirements and technical specifications.

Black-box Testing examples

• You test a word processor. You create, save, open, and delete files. You test if the files are saved correctly, opened without errors, and deleted permanently.
• You test a website. You enter your username and password. You test if you can log in successfully, access various web pages, and log out completely.
• You test a calculator app. You enter multiple test expressions, with numbers and operators. You test if the app rejects invalid inputs, calculates the correct results, and displays clear error messages or results.
• You test an online game. In the game, you play explore, collect items, fight enemies, and play different levels. You test if the game play is logical, challenging, and complete and if the game assets are correct.

Tips for Black-box Testing

• Use different test techniques to design test cases, such as equivalence partitioning, boundary value analysis, decision table testing, and state transition testing. These test techniques help you reduce the number of tests needed for the same coverage.
  
• Test both invalid and valid inputs to know if the software handles them correctly.
  
• Test all relevant subsystems of the software, such as UI/UX (user interface/ user experience), website, database, etc.
• Use tools to automate the testing tasks, such as generating test data for inputs, executing tests, and reporting results.

FAQ (interview questions and answers)

1. What is the difference between black-box testing and white-box testing?
   Black-box testing tests the software without using the knowledge of its architecture or code. White-box testing tests the software using the knowledge of its software architecture and code.
2. What are the benefits of black-box testing?
   It can test the software from the user's perspective. It requires testing skills and industry domain knowledge, but does not require deep code knowledge. Still, basic code knowledge helps in designing all relevant tests.
3. What challenge have you faced in black-box testing?
   Since the knowledge of code is not used, it can be hard to pinpoint the root cause of a defect. It can be difficult to measure test coverage.
4. Is boundary value analysis a type of black-box testing?
   Yes, it is a test technique to test input values at or near the boundaries.

Remember to just comment if you have any doubts or queries.