Essential Work Sample Exercises for Hiring Top Software Development Engineers in Test

Software Development Engineers in Test (SDETs) play a critical role in ensuring software quality while bridging the gap between development and testing. Unlike traditional QA roles, SDETs combine programming expertise with testing knowledge to build robust test automation frameworks, identify edge cases, and contribute to overall product quality.

Finding the right SDET requires evaluating both technical skills and problem-solving abilities. Traditional interviews often fail to reveal how candidates approach real-world testing challenges or how they write maintainable test code. Work samples provide a window into a candidate's actual capabilities rather than their interview skills.

The best SDETs demonstrate a unique blend of developer mindset and tester intuition. They not only write clean, efficient code but also possess the ability to anticipate failure points and edge cases that developers might miss. Work samples allow you to observe these qualities in action.

The exercises below are designed to evaluate key SDET competencies: test automation skills, strategic test planning, debugging abilities, and code quality assessment. By incorporating these work samples into your interview process, you'll gain deeper insights into each candidate's capabilities and identify those who will truly excel in your testing environment.

Activity #1: Test Automation Framework Design and Implementation

This exercise evaluates a candidate's ability to design and implement automated tests using industry-standard frameworks. It reveals their coding skills, understanding of test architecture, and ability to create maintainable test solutions.

Directions for the Company:

• Provide the candidate with a simple web application or API to test (this could be a public demo app or a simplified version of your product).
• Share documentation about the application's functionality and expected behavior.
• Ask the candidate to design and implement an automated test framework that covers key functionality.
• Allow 2-3 hours for this exercise, which can be done as a take-home assignment.
• Provide access to a repository where they can commit their code.

Directions for the Candidate:

• Review the application documentation to understand its functionality.
• Design a test automation framework that follows best practices (modular, maintainable, readable).
• Implement automated tests for at least 3-5 key user flows or API endpoints.
• Include appropriate assertions to verify expected behavior.
• Document your approach, including framework architecture decisions and any assumptions made.
• Submit your code to the provided repository with clear instructions on how to run the tests.

Feedback Mechanism:

• After reviewing the submission, provide feedback on one aspect the candidate did well (e.g., test organization, code quality, coverage strategy) and one area for improvement.
• During a follow-up discussion, ask the candidate to explain how they would refactor or enhance their solution based on the improvement feedback.
• Give them 15-20 minutes to make a small improvement to their code based on the feedback.

Activity #2: Test Strategy and Planning

This exercise assesses a candidate's ability to think strategically about testing, prioritize test efforts, and communicate testing approaches effectively. It reveals their understanding of testing methodologies and risk assessment.

Directions for the Company:

• Provide a product specification or feature description document for a new feature or product.
• Include information about target users, technical architecture, and business goals.
• Ask the candidate to create a comprehensive test strategy and plan.
• Allow 1-2 hours for this exercise, which can be done as a take-home assignment or during an interview.

Directions for the Candidate:

• Review the product specification to understand the feature's functionality and requirements.
• Create a test strategy document that includes:
• Types of testing required (functional, performance, security, etc.)
• Test environments needed
• Test data requirements
• Risk assessment and prioritization
• Automation vs. manual testing approach
• Test metrics and success criteria
• Outline a high-level test plan with estimated effort and timeline.
• Be prepared to present and discuss your strategy in a follow-up interview.

Feedback Mechanism:

• After the candidate presents their test strategy, provide feedback on one strength (e.g., comprehensive coverage, good risk assessment) and one area for improvement.
• Ask the candidate to revise one section of their strategy based on the feedback.
• Give them 10-15 minutes to adjust their approach and explain their revised thinking.

Activity #3: Bug Investigation and Root Cause Analysis

This exercise evaluates a candidate's debugging skills, analytical thinking, and ability to communicate technical issues clearly. It reveals how they approach problem-solving and their attention to detail.

Directions for the Company:

• Prepare a simple application with intentionally introduced bugs (ideally representing common issues in your codebase).
• Create a bug report with symptoms but without revealing the root cause.
• Provide access to the application code, logs, and any necessary debugging tools.
• Allow 45-60 minutes for this exercise during an interview.

Directions for the Candidate:

• Review the bug report to understand the reported issue.
• Investigate the application to reproduce the bug and identify potential causes.
• Use debugging tools and log analysis to narrow down the root cause.
• Document your investigation process, including:
• Steps to reproduce the issue
• Observations and findings
• Root cause analysis
• Recommended fix
• Suggestions for preventing similar issues in the future
• Be prepared to explain your approach and findings.

Feedback Mechanism:

• After the candidate presents their findings, provide feedback on one strength (e.g., thorough investigation, clear explanation) and one area where their approach could be improved.
• Ask the candidate to refine their root cause analysis or suggested fix based on the feedback.
• Give them 10 minutes to revise their approach and explain their new thinking.

Activity #4: Code Review and Quality Assessment

This exercise assesses a candidate's ability to identify code quality issues, security vulnerabilities, and potential bugs. It reveals their attention to detail and understanding of software engineering best practices.

Directions for the Company:

• Prepare a code sample (200-300 lines) with intentionally introduced issues, including:
• Functional bugs
• Performance issues
• Security vulnerabilities
• Code style and maintainability problems
• Missing test coverage
• The code should be relevant to your tech stack but not overly complex.
• Allow 30-45 minutes for this exercise during an interview.

Directions for the Candidate:

• Review the provided code sample thoroughly.
• Identify and document issues in the following categories:
• Functional bugs or logical errors
• Performance concerns
• Security vulnerabilities
• Code quality and maintainability issues
• Testing gaps
• For each issue, provide:
• Description of the problem
• Potential impact
• Suggested improvement
• Prioritize the issues based on their severity and impact.
• Be prepared to discuss your findings and recommendations.

Feedback Mechanism:

• After the candidate presents their code review, provide feedback on one strength (e.g., thoroughness, prioritization) and one area for improvement.
• Ask the candidate to elaborate on how they would address one specific issue they identified, incorporating the feedback provided.
• Give them 10 minutes to develop a more detailed solution for that issue.

Frequently Asked Questions

How long should we allocate for these work samples in our interview process?

The test automation exercise works best as a take-home assignment (2-3 hours), while the other exercises can be conducted during interviews (30-60 minutes each). Consider spreading them across different interview stages rather than conducting all in one day to avoid candidate fatigue.

Should we use our actual product code for these exercises?

It's best to use simplified versions of your actual systems or public demo applications. Using your real product provides more relevant context, but ensure you're not sharing sensitive code or requiring extensive product knowledge to complete the exercises.

How should we evaluate candidates who use different tools or approaches than we currently use?

Focus on the principles and reasoning behind their choices rather than specific tools. A strong candidate might introduce you to better approaches than your current ones. Evaluate their problem-solving process, code quality, and testing mindset rather than exact technology matches.

What if a candidate doesn't complete the exercise in the allotted time?

This is valuable information in itself. Discuss what they prioritized and why. A partial solution with good quality and clear explanation of trade-offs often reveals more about a candidate's abilities than a rushed complete solution.

How can we make these exercises inclusive for candidates with different backgrounds?

Provide clear instructions and context. Allow candidates to use tools and languages they're comfortable with when possible. Focus evaluation on problem-solving approach and testing principles rather than specific technology knowledge that can be learned on the job.

Should we compensate candidates for take-home assignments?

For longer take-home exercises (especially the test automation framework), consider offering compensation for the candidate's time. This demonstrates respect for their effort and helps ensure candidates from all backgrounds can participate in your process.

Finding the right SDET is crucial for building quality into your development process from the start. These work samples will help you identify candidates who not only have the technical skills but also the testing mindset needed to excel in this role. By observing how candidates approach real-world testing challenges, you'll gain deeper insights than traditional interviews alone can provide.

For more resources to improve your hiring process, check out Yardstick's AI Job Descriptions, AI Interview Question Generator, and AI Interview Guide Generator.

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