Interview

20 Test-Driven Development Interview Questions and Answers

Prepare for the types of questions you are likely to be asked when interviewing for a position where Test-Driven Development will be used.

Test-driven development (TDD) is a popular development methodology in which tests are written before code is written. This approach allows developers to ensure that their code meets the requirements and that it is properly tested before it is deployed. If you are interviewing for a position that requires TDD, you can expect to be asked questions about your experience with this methodology. In this article, we will review some common TDD interview questions and how you should answer them.

Test-Driven Development Interview Questions and Answers

Here are 20 commonly asked Test-Driven Development interview questions and answers to prepare you for your interview:

1. What do you understand about Test-Driven Development?

Test-Driven Development is a development methodology in which tests are written before code is written. This allows developers to ensure that their code is meeting the requirements set forth by the tests. It also allows for a more incremental and iterative development process, as tests can be written and run on small pieces of code as they are developed.

2. Can you explain the main steps involved in TDD?

The main steps involved in TDD are: 1) writing a test case, 2) running the test case to see if it fails, 3) writing code to make the test case pass, and 4) re-running the test case to ensure it now passes. These steps are then repeated for each new feature or functionality that is added to the code.

3. How does TDD differ from agile development processes?

TDD is a development methodology that puts tests first, before any code is written. The idea is that by writing tests first, you can ensure that your code meets the requirements set out by the tests. This is in contrast to agile development processes, which focus on delivering working code as quickly as possible.

4. What are some advantages and disadvantages of using TDD?

Some advantages of using TDD include that it can help produce more reliable and bug-free code, and can also help developers to think more carefully about the design of their code before they start writing it. Some disadvantages of using TDD include that it can be time-consuming, and may not be suitable for all types of projects.

5. When can you say that a project has reached its testing goals?

A project has reached its testing goals when all of the planned tests have been completed and the results meet the expectations.

6. Do all projects need to be tested before going live? If not, then when should testing be skipped?

No, all projects do not need to be tested before going live. In some cases, it may not be possible or practical to test every aspect of a project before it is launched. In other cases, it may not be necessary to test every aspect of a project if it is not mission-critical or if it has already been thoroughly tested in a previous iteration. Ultimately, it is up to the project manager or development team to decide when testing can be skipped.

7. What is your opinion on automated testing?

I believe that automated testing is an essential part of the software development process. Automated tests can help to ensure that your code is working as expected and can help to catch bugs early on in the development process.

8. Are there any alternatives to TDD for software development? Which one would you recommend? Why?

There are a few alternatives to TDD for software development, but the one that I would recommend is BDD, or behavior-driven development. BDD focuses on specifying the behavior of a system before writing any code, which can help to ensure that the code that is ultimately written meets the requirements.

9. Is it possible to use TDD without writing unit tests?

No, it is not possible to use TDD without writing unit tests. TDD is a methodology that relies on the creation of unit tests in order to drive the development process. Without unit tests, there would be no way to verify that the code you are writing is actually working as intended.

10. Can you give me a real-world example where TDD was used successfully?

There are many examples of successful TDD implementations, but one that stands out is the development of the Linux kernel. The Linux kernel is a complex piece of software, and TDD was used extensively during its development in order to ensure that the code was of the highest quality. This approach proved to be successful, as the Linux kernel is now one of the most widely used pieces of software in the world.

11. What do you think about developer documentation? Why is it important?

I think developer documentation is important because it can help developers understand the code they are working on, as well as provide a reference for future development.

12. What is more important: code coverage or test coverage? Explain your answer.

There is no definitive answer to this question, as it depends on the specific project and what the goals are. However, in general, code coverage is more important than test coverage. This is because code coverage measures the percentage of code that is executed by your tests, while test coverage measures the percentage of tests that cover a particular piece of code. Therefore, code coverage is a more accurate measure of how well your tests are actually testing your code.

13. Why should developers perform their own testing tasks instead of delegating them to QA teams?

Developers should perform their own testing tasks for a number of reasons. First, it helps to ensure that the code they are writing is actually working as intended. Second, it can help to find bugs early on in the development process, before they have a chance to become more difficult and expensive to fix. Finally, it can help developers to better understand the code they are working on, and how it interacts with the rest of the system.

14. Is it necessary to follow each step in the TDD process? What happens if we skip a step?

No, it is not necessary to follow each step in the TDD process. However, if you do skip a step, it can impact the quality of your tests and the efficiency of your development process. For example, if you skip the step of writing a test before you write code, you may end up with code that is difficult to test or that has a lot of bugs.

15. Can you please describe the Red/Green/Refactor phase of TDD?

The Red/Green/Refactor phase of TDD is a process for writing code that begins with writing a failing test (the “red” phase). Once the test is written, you then write the code necessary to make the test pass (the “green” phase). Finally, you refactor the code to make it more efficient or readable (the “refactor” phase). This process is repeated until all desired functionality is complete.

16. What do you understand by “regression testing”?

Regression testing is a process of testing software to ensure that changes or new features have not caused any unintended effects elsewhere in the code. This is typically done by rerunning existing tests to ensure that they still pass, as well as creating new tests specifically designed to exercise the new code.

17. What is an exploratory testing session?

An exploratory testing session is a session in which the tester is free to explore the software under test, without following any specific test plan or script. This type of testing can be useful for uncovering new areas of the software that may need to be tested, or for testing in an agile environment where the requirements may change frequently.

18. What’s the difference between black box and white box testing?

Black box testing is a method of testing where the tester does not have access to the inner workings of the system being tested. White box testing is a method of testing where the tester does have access to the inner workings of the system being tested.

19. What’s the difference between manual and automated testing?

Automated testing is a process of running tests on your code using a software tool, while manual testing involves a human tester running the tests. Automated testing is generally faster and more reliable than manual testing, but it can be more expensive to set up and maintain.

20. What’s the difference between functional and non-functional testing?

Functional testing is testing that verifies the functionality of the software, while non-functional testing is testing that verifies the non-functional aspects of the software, such as performance, scalability, etc.

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