Quest Diagnostics Software Engineer Interview Questions + Guide in 2025

Quest Diagnostics is a leading provider of diagnostic information services, helping patients and healthcare providers make informed decisions through a comprehensive range of tests and services.

The Software Engineer role at Quest Diagnostics involves working as part of an agile team to design, develop, test, and deploy software solutions that enhance operational efficiency and improve user experience across various applications. Key responsibilities include participating in the full Software Development Life Cycle (SDLC), writing high-quality code, and collaborating with cross-functional teams to gather requirements, troubleshoot issues, and implement innovative solutions. A great fit for this role would have experience in full-stack development, familiarity with cloud technologies, and a strong grasp of agile methodologies. The ideal candidate should also possess excellent problem-solving skills, a solid understanding of programming languages such as Python and SQL, and the ability to communicate effectively with both technical and non-technical stakeholders.

This guide aims to equip you with insights and specific areas to focus on as you prepare for your interview at Quest Diagnostics, ensuring you present your qualifications effectively and align with the company’s innovative and collaborative culture.

The interview process for a Software Engineer at Quest Diagnostics is structured and designed to assess both technical and interpersonal skills. Candidates can expect a series of interviews that evaluate their fit for the role and the company culture.

1. Initial Screening

The process typically begins with an initial screening conducted by a recruiter. This is a phone interview where the recruiter will discuss your background, experience, and motivations for applying to Quest Diagnostics. They will also provide insights into the company culture and the specifics of the role. This is an opportunity for you to ask questions and gauge if the position aligns with your career goals.

2. Technical Interview

Following the initial screening, candidates who pass will be invited to a technical interview. This may be conducted over the phone or via video conferencing. During this interview, you will be assessed on your technical skills relevant to software development, including programming languages, algorithms, and problem-solving abilities. Expect to discuss your previous projects and how you approached various technical challenges. You may also be asked to solve coding problems or explain your thought process in real-time.

3. Onsite Interview

Candidates who perform well in the technical interview will be invited for an onsite interview. This stage typically involves multiple rounds with different team members, including hiring managers and potential colleagues. The onsite interviews will cover a mix of technical and behavioral questions. You will be expected to demonstrate your coding skills, discuss your experience in software development, and showcase your ability to work collaboratively in a team environment. Additionally, you may be asked to participate in a coding exercise or a system design discussion.

4. Final Interview

The final stage of the interview process often includes a discussion with HR or senior management. This interview focuses on cultural fit, your long-term career aspirations, and how you align with the company's values. You may also discuss salary expectations and benefits during this stage.

Throughout the interview process, it is crucial to demonstrate not only your technical expertise but also your communication skills and ability to work in a team. Be prepared to provide examples from your past experiences that highlight your problem-solving abilities and adaptability.

As you prepare for your interviews, consider the types of questions that may arise, particularly those related to your technical skills and past projects.

In this section, we’ll review the various interview questions that might be asked during a Software Engineer interview at Quest Diagnostics. The interview process will likely focus on your technical skills, problem-solving abilities, and experience in software development, particularly in an agile environment. Be prepared to discuss your past projects, coding practices, and how you approach challenges in software engineering.

Technical Skills

1. How would you handle an infinite loop in your code?

This question assesses your debugging skills and understanding of control flow in programming.

How to Answer

Explain your approach to identifying and resolving infinite loops, including the tools or techniques you would use to debug the issue.

Example

“I would start by reviewing the loop conditions and ensuring they are set to eventually terminate. I would use debugging tools to step through the code and identify where the logic fails. If necessary, I would add logging statements to track the loop's execution and pinpoint the issue.”

2. Can you explain the difference between a stack and a queue?

This question tests your understanding of data structures and their applications.

How to Answer

Define both data structures and provide examples of when you would use each.

Example

“A stack is a Last In First Out (LIFO) structure, where the last element added is the first to be removed, like a stack of plates. A queue, on the other hand, is a First In First Out (FIFO) structure, where the first element added is the first to be removed, similar to a line at a ticket counter.”

3. Describe your experience with version control systems.

This question evaluates your familiarity with collaborative coding practices.

How to Answer

Discuss the version control systems you have used, your experience with branching and merging, and how you manage code changes in a team environment.

Example

“I have extensive experience using Git for version control. I regularly create branches for new features and use pull requests to facilitate code reviews. This process helps maintain code quality and allows for collaborative development.”

4. What is your approach to writing unit tests?

This question assesses your understanding of testing practices in software development.

How to Answer

Explain the importance of unit testing and your methodology for writing effective tests.

Example

“I believe unit tests are crucial for ensuring code reliability. I typically write tests alongside my code, focusing on edge cases and expected outcomes. I use frameworks like JUnit for Java or pytest for Python to automate the testing process.”

5. How do you ensure the security of your applications?

This question gauges your awareness of security best practices in software development.

How to Answer

Discuss the security measures you implement during development and any relevant frameworks or tools you use.

Example

“I prioritize security by following best practices such as input validation, using prepared statements to prevent SQL injection, and regularly updating dependencies. I also conduct code reviews focused on security vulnerabilities and utilize tools like OWASP ZAP for security testing.”

Problem-Solving and Analytical Skills

1. Describe a challenging technical problem you faced and how you resolved it.

This question evaluates your problem-solving skills and resilience.

How to Answer

Provide a specific example, detailing the problem, your approach to solving it, and the outcome.

Example

“While working on a project, I encountered a performance bottleneck in our application. I profiled the code and discovered that a specific database query was inefficient. I optimized the query by adding indexes and restructuring it, which improved the application’s response time significantly.”

2. How do you prioritize tasks when working on multiple projects?

This question assesses your time management and organizational skills.

How to Answer

Explain your approach to prioritization, including any tools or methodologies you use.

Example

“I prioritize tasks based on deadlines and project impact. I use tools like Jira to track progress and ensure that I’m focusing on high-priority items first. Regular check-ins with my team also help align our priorities.”

3. Can you explain a time when you had to learn a new technology quickly?

This question tests your adaptability and willingness to learn.

How to Answer

Share a specific instance where you successfully learned a new technology and applied it to a project.

Example

“When our team decided to implement a microservices architecture, I had to quickly learn Docker and Kubernetes. I dedicated time to online courses and hands-on practice, which allowed me to contribute effectively to the deployment process.”

4. How do you approach debugging a complex issue?

This question evaluates your analytical thinking and troubleshooting skills.

How to Answer

Outline your systematic approach to debugging, including any tools or techniques you use.

Example

“I start by reproducing the issue to understand its context. Then, I use logging to gather more information about the state of the application. I break down the problem into smaller parts and test each component until I identify the root cause.”

5. What motivates you to write clean and maintainable code?

This question assesses your coding philosophy and commitment to quality.

How to Answer

Discuss the importance of clean code and how it impacts collaboration and future development.

Example

“I’m motivated to write clean code because it enhances collaboration and reduces technical debt. Clean code is easier to read and maintain, which ultimately leads to more efficient development cycles and fewer bugs in the long run.”