10 Software testing (pytest, doctest) Interview Questions and Answers for python engineers

flat art illustration of a python engineer

1. Can you walk me through your experience with pytest and doctest?

During my previous role as a software tester at XYZ company, I utilized both pytest and doctest extensively. Pytest is a powerful testing framework that allowed me to easily write and execute automated tests for Python code. I have written over 100 test cases using pytest, covering various scenarios such as edge cases, negative testing, and performance testing. Through these tests, I was able to identify numerous issues and bugs, resulting in a significant decrease in the number of bugs reported by end-users.

In addition to pytest, I have also used doctest to test Python code. Doctest is a lightweight testing framework that allows you to write tests within the code itself. This allowed me to easily identify and fix bugs early on in the development process. I have written over 50 tests using doctest, covering both positive and negative scenarios.

Furthermore, I have integrated both pytest and doctest into the CI/CD pipeline, allowing for automated testing of every code change. This helped to catch issues early on, reducing development time and improving the overall quality of the product.

One example of my successful use of pytest and doctest was during the testing of an e-commerce website. I wrote automated tests using pytest to simulate user activity on the website, such as adding items to the cart and checking out. I was able to identify a critical bug where the website would crash when multiple users attempted to check out simultaneously. This was caught early on due to the automated testing, preventing any negative impact on end-users.

Overall, my experience with both pytest and doctest has proven to be invaluable in improving the overall quality of software development. I am confident in my ability to continue utilizing these frameworks in future testing projects.

2. What testing frameworks have you used, and which do you prefer?

Throughout my career as a software tester, I have used various testing frameworks such as pytest and doctest. Both of these frameworks have their own strengths and weaknesses, and I think it depends on the project and its specific requirements as to which I prefer.

  1. Pytest:

    • Pytest is one of the most popular testing frameworks and is known for its simple syntax, flexibility and powerful reporting.
    • In a previous project, I was able to implement pytest for regression testing and we were able to achieve a 98% pass rate for our test suites.
    • Pytest allowed us to easily organize our test cases into different modules and fixtures, which made our test suites more maintainable and scalable.
  2. Doctest:

    • Doctest is a lightweight testing framework that allows you to write tests directly in your documentation strings, making it easier to maintain tests alongside your code.
    • During a recent project, I implemented doctest for unit testing, and was able to catch a few edge cases that traditional unit tests might have missed.
    • Doctest also helped improve our documentation, as it enforced the accuracy of the code samples we included to ensure they were working as intended.

Overall, I believe that both pytest and doctest have their own strengths and can be effective for testing. I would be happy to discuss which testing framework would be best suited for your specific project needs.

3. How do you decide what areas of the code need to be tested?

As a software tester, the decision on which areas of the code need to be tested usually depends on several factors. To determine the areas to be tested, I typically:

  1. Review the project requirements, including functional, technical and performance requirements
  2. Use code coverage tools to analyze the source code and determine which classes, methods or functions have been changed or added recently
  3. Identify the most critical or high-risk parts of the code that are more likely to cause failures, such as complex algorithms or integrations with external systems
  4. Use risk-based testing techniques to prioritize the areas and ensure that the most critical functions or use cases are adequately tested
  5. Consider testing the areas that have had the most defects reported in previous iterations or releases of the software

I also take into account the project timelines, available resources and budget constraints when deciding which areas of the code to test. This approach has enabled me to achieve a high test coverage, reduce defects and enhance the quality of the software.

For instance, in my previous project, I reviewed the requirements and identified the critical areas of the code that needed to be tested. I also applied risk-based testing to prioritize the most important areas to test. Using this approach, I was able to achieve 95% test coverage and reduce the average number of defects by 60% from one release to the other.

4. What is your approach to testing user interfaces?

My approach to testing user interfaces involves conducting extensive manual testing as well as utilizing automated tools such as Pytest and Doctest. When testing user interfaces, I focus on ensuring that the UI is intuitive and user-friendly, and that all buttons and features are functioning correctly.

  • I begin by creating test cases that cover all possible user actions and edge cases.
  • Next, I use Pytest and Doctest to run automated tests, and analyze the results to identify any issues or bugs.
  • Afterwards, I conduct manual testing, taking notes and creating screenshots to document any issues that arise.
  • Finally, I collaborate with the development team to address any identified issues, ensuring that they are resolved and that the UI is functioning optimally.

This approach has resulted in significant improvements in user satisfaction and engagement, with a 20% increase in user retention and a 15% increase in user interaction with the UI. Additionally, it has reduced the time to identify and fix issues by 30%, resulting in a more streamlined development process.

5. In your opinion, what is the most difficult aspect of software testing, and how do you handle it?

One of the most challenging aspects of software testing is being able to identify and replicate bugs effectively. This can be especially difficult when dealing with complex systems that involve multiple components and dependencies.

To overcome this challenge, I have developed a comprehensive testing process that involves detailed documentation and thorough testing scenarios. I start by analyzing the system's architecture and identifying its critical components. Then, I create a detailed test plan that includes various testing scenarios that cover both positive and negative cases.

  1. Functional testing – Verifying that the software meets the specifications and requirements.
  2. Performance testing – Evaluating the software's performance under various loads.
  3. Security testing – Ensuring that the software is secure from any potential threats.
  4. Integration testing – Checking that the software is working together as intended when multiple components are involved.

To further streamline the testing process, I implement automation testing tools such as pytest and doctest. These tools have shown to significantly reduce the time and effort it takes to catch complex bugs and ensure the highest quality of software.

Additionally, I continuously collaborate with the development team to maintain effective communication and stay up-to-date with new features and changes. This proactive approach ensures that any potential issues are identified and resolved as soon as possible, ultimately resulting in faster delivery time and increased customer satisfaction.

6. What is your process for identifying, reporting, and tracking bugs?

As a software tester, my process for identifying, reporting, and tracking bugs involves a series of steps:

  1. Identifying the Bug: I start by thoroughly testing the software to look for any bugs or glitches that could impede performance or functionality.
  2. Reporting the Bug: Once a bug is identified, I report it as soon as possible to the development team. I create a bug report that includes detailed information on the issue, such as the steps to reproduce it, the severity of the bug, and any screenshots or error messages.
  3. Tracking the Bug: Once the bug is reported, I use a bug tracking system to keep track of the issue until it is resolved. I assign the bug to the appropriate team member and monitor progress to make sure it is resolved in a timely manner.
  4. Verifying the Fix: Once the bug is fixed, I perform regression testing to ensure that the fix did not create any new issues. If the bug is completely fixed, I close the bug report. If not, I reopen the bug report and work with the development team to resolve the issue.

Using this process, I was able to contribute to a significant reduction in software defects for a previous employer. By actively reporting and tracking bugs, we were able to identify patterns and address underlying issues in the code. As a result, we saw a 35% decrease in the number of bugs reported by end-users over the course of six months.

7. What types of testing strategies do you think are most effective for ensuring software quality?

When it comes to ensuring software quality, I believe that implementing a combination of testing strategies is most effective. This includes:

  1. Unit Testing: This involves testing individual units or components of the software. By testing each unit separately, it allows for early detection of bugs and makes it easier to pinpoint the source of the problem. In my previous role, implementing unit testing resulted in a 30% reduction in bug reports from our users.
  2. Integration Testing: This strategy involves testing how different units work together. This is essential as even if each unit has been tested individually, it doesn't guarantee that they will work together flawlessly. By implementing integration testing, we were able to catch 90% of the bugs before releasing the product to our users.
  3. Functional Testing: This involves testing how the software performs based on the functional requirements. This testing strategy simulates real-world scenarios to ensure that the software meets the users' needs. In my previous role, we implemented functional testing and saw a 25% reduction in product downtime due to bugs.
  4. Acceptance Testing: This strategy involves testing how well the software meets the user's expectations. This testing can be done by the users themselves or by a separate team who will test against the user's requirements. In my previous role, we saw an 80% increase in customer satisfaction ratings after implementing acceptance testing.

Overall, implementing a combination of testing strategies is essential for ensuring software quality. By doing so, it reduces the number of bugs reported by users and increases customer satisfaction ratings.

8. Have you ever had to develop a test suite from scratch? Can you describe the process you followed?

Yes, I have had to develop a test suite from scratch for a previous project. The process I followed involved the following steps:

  1. First, I familiarized myself with the software requirements and the scope of the project to identify the functionalities that needed to be tested.
  2. Next, I determined the testing methodology that would be appropriate for the project, such as manual testing, automated testing or a combination of both.
  3. I then created a test plan that listed each test case and the expected results.
  4. Once the test plan was approved, I began writing test cases and building out an automated test suite using pytest.
  5. During the development of the test suite, I worked closely with the development team to identify and resolve any issues that came up.
  6. After the test suite was completed, I executed the test cases and documented the results in a clear and concise manner. I also tracked any defects that were found and worked with the development team to resolve them.
  7. Finally, I conducted a post-implementation review to identify any areas for improvement and to ensure that the test suite was effective in meeting the project requirements.

As a result of this process, we were able to identify and resolve several critical defects before the software was released, which resulted in a more stable and reliable product for our end-users.

9. How do you stay up-to-date on changes and advancements in testing frameworks and methodologies?

As a software tester, staying up-to-date on changes and advancements in testing frameworks and methodologies is crucial for success. In order to stay current, I actively participate in online communities related to software testing, such as Reddit, LinkedIn groups and testers.io forums where I can learn from other professionals and share my own experience as well. I also regularly attend industry conferences and meetups.

  1. I recently attended the Selenium Conference where I learned about the latest features and advancements in the Selenium framework. I gained knowledge on web automation testing, optimization of tests, and best practices for maintainable codes. I was particularly interested in the talk on how AI and machine learning are being used to build smarter testing tools.
  2. I'm subscribed to several software testing journals, including Better Software Magazine and Stickyminds, which I read regularly to stay up on the latest techniques, frameworks, and approaches to software testing.
  3. I also make sure to participate in webinars hosted by leading experts in the field. Recently, I attended a webinar series on pytest testing framework for Python, which helped me get up to speed on the latest features and best practices in the framework.

Aside from external learning, I also take time to practice and experiment with new frameworks and methodologies in my own projects. Through this hands-on experience, I've been able to gain a deeper understanding of how to optimize for speed and efficiency with pytest and doctest frameworks.

By actively seeking out opportunities to learn and experiment, not only am I able to stay current with the latest testing frameworks and methodologies, but I'm also able to apply that knowledge to making a larger contribution in my role as a software tester.

10. What is your experience with continuous integration and continuous deployment (CI/CD) in a testing environment?

During my previous role as a Test Automation Engineer at XYZ Company, I had the opportunity to work on a project that utilized continuous integration and continuous deployment (CI/CD) for testing. Our team had implemented a CI/CD pipeline using Jenkins and GitLab to automate the execution of our test suites and deployment of our code.

  1. As a result, we were able to reduce our testing cycle time by 50% and increase the frequency of our releases from once every two weeks to twice a week.
  2. In addition, we reduced the number of bugs that made it to production by 70% due to the early and frequent testing in the pipeline.
  3. Our team also maintained a high level of code quality, with a code coverage of 90% on average using pytest and doctest frameworks.

I also had the opportunity to work with the development team to ensure that the tests were integrated into their workflow and reviewed their code changes before they were merged into the pipeline. This helped to catch any bugs or issues early on, ensuring that the pipeline remained stable and reliable.

Overall, my experience with CI/CD testing has shown me the value of automating the testing process, which not only saves time and increases efficiency, but also leads to higher-quality code and a better user experience.


Congratulations on mastering these 10 software testing interview questions for 2023! Now it's time to take the next steps towards landing your dream job. Don't forget to write an impressive cover letter that highlights your skills and experience. Check out our guide on writing a cover letter for Python Engineers for helpful tips and tricks.

Another crucial step is to prepare a well-crafted CV that showcases your qualifications. Our guide on writing a resume for Python Engineers provides valuable guidance.

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