What QA Engineers Underestimate in Technical Coding Interviews

If you’re aiming for a career in test automation, one of the biggest hurdles you’ll face is the coding round in interviews. Many candidates prepare for months, solve numerous coding problems, and still find themselves struggling. Why? Because they lack strategy.

In this playbook, I’ll walk you through a step-by-step approach that will not only help you pass the coding round but also make you stand out as a strong automation engineer.

Step 1: Understand the Problem Statement

The first mistake many candidates make is rushing to write code without truly understanding the problem. Avoid this!

Break it down: Identify keywords, constraints, and expected input/output.

Ask clarifying questions: Are negative numbers allowed? How large is the input? Should I optimize for time or space?

Rephrase the problem: Say it out loud or write it in plain English before diving into code.

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Step 2: Consider Edge Cases

Most coding problems include hidden complexities. A good automation engineer anticipates these.

Think about:

• Empty inputs
• Large data sets (performance concerns)
• Special characters (if dealing with strings)
• Duplicates or missing values (in arrays)

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Step 3: Start with a Brute-Force Approach

Before optimizing, quickly draft a basic solution that works. Interviewers prefer candidates who first get a working solution, then optimize it.

Example: If asked to find duplicates in an array, a simple nested loop approach is okay at first. Later, you can improve it using a HashSet for faster lookups.

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Step 4: Optimize with the Best Approach

Once your brute-force solution works, discuss its time and space complexity.

Use techniques like:

• Sorting to simplify problems
• HashMaps for quick lookups
• Two Pointers for optimized searches
• Recursion vs. Iteration for clarity and efficiency

Show the interviewer that you think in steps and understand Big O Notation.

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Step 5: Write Clean & Readable Code

A well-structured, readable solution is always better than a clever but unreadable one.

Best Practices:

• Use meaningful variable names (not x, y, or z)
• Add comments to explain logic
• Follow indentation and clean formatting

Even if your code is perfect, bad formatting can cost you points!

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Step 6: Dry Run Your Code (Manually Walk Through It)

Don’t assume your code is correct—validate it before running it.

Test with sample inputs Walk through each loop/condition mentally Predict the output before executing

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Step 7: Explain Time & Space Complexity

Every interviewer expects you to evaluate your solution.

Answer questions like:

• Can this solution handle millions of records?
• Will it cause a stack overflow?
• Can I optimize further?

Example: If your solution takes O(n²), discuss how you could improve it to O(n log n) or O(n).

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Step 8: Consider Further Optimization

Once your solution works, challenge yourself:

“Can I do this with less memory?” “Can I avoid using extra loops?” “Can I preprocess data for faster access?”

Even if you don’t find a better approach, this shows your problem-solving mindset.

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Step 9: Communicate Effectively

Coding rounds are not just about writing code. They’re about how well you explain your thought process.

Tips for clear communication:

• Think out loud while coding
• Use whiteboard space wisely (if in-person)
• Explain why you made a particular choice
• Be confident but open to feedback

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Step 10: Seek Feedback & Improve

Even if you don’t clear an interview, treat it as a learning experience.

Ask the interviewer:

• “What could I have done better?”
• “Was there a more optimal approach?”
• “Which skills should I improve on?”

Every interview is a stepping stone to the next!

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Bonus: Coding Topics to Focus On

To succeed in automation coding rounds, focus on these key areas:

1Data Structures

Arrays & Strings
HashMaps & Sets
Stacks & Queues
Linked Lists
Trees & Graphs

2Algorithms

Sorting (QuickSort, MergeSort)
Searching (Binary Search, BFS/DFS)
Dynamic Programming
Recursion

3Automation-Specific Concepts

Locators (XPath, CSS Selectors)
API Testing with RestAssured
Framework Design (Selenium, Cypress, Playwright)
Parallel Execution & CI/CD Integration

Master these, and you’ll ace any automation coding challenge!

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Final Words

Cracking a test automation coding round isn’t just about knowing how to code—it’s about having a structured approach, problem-solving mindset, and clear communication skills.

• Practice coding problems daily (LeetCode, CodeSignal, HackerRank).
• Focus on test automation-specific problems (working with locators, handling waits, test data management, etc.).
• Master one programming language (Python, Java, or JavaScript).
• Learn common algorithms & data structures (sorting, searching, recursion, trees, graphs).
• Time yourself—most coding rounds have a strict time limit!

Follow these 10 steps, practice consistently, and you’ll be well on your way to clearing any automation interview!

Good luck!

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