ACCELDATA – Senior SDET Interview (Round 3)

Questions & Sample Answers

Overview: These were the actual questions asked to me in the Acceldata Senior SDET (Round 3) interview.

My experience level at the time of the interview was 4+ years.

This round focused on:

• Docker & Kubernetes fundamentals

• Linux command clarity

• Data processing coding problem

• Tree/recursion-based problem solving

• Test case design thinking

• Framework maturity & real challenges

The discussion tested:

• Problem-solving depth

• System thinking

• Structured test design

• Practical DevOps knowledge

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Question 1: Few Docker Questions

Topics covered:

• What is Docker?

• Difference between Image and Container

• Docker lifecycle

• Dockerfile instructions (FROM, RUN, COPY, CMD)

• Difference between CMD and ENTRYPOINT

• docker build, run, ps, logs

Focus was on practical understanding rather than definitions.

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Question 2: Few Kubernetes Questions

Topics covered:

• Pods, Deployments, Services

• NodePort vs ClusterIP

• LoadBalancer usage

• CrashLoopBackOff

• ImagePullBackOff

• How to debug failed pods

The interviewer checked troubleshooting ability.

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Question 3: Difference between du and df in Linux.

Answer:

df (Disk Free)

• Shows disk space usage of file system

• Displays total, used, available space

du (Disk Usage)

• Shows disk usage of files/directories

• Used to find which folder consumes space

Example:

df -h
du -sh *

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Coding Question – CSV Processing

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Question 4: Given a CSV file with City, Country, Temp – Find average temperature per country.

Answer:

Approach:

• Read CSV line by line

• Maintain a dictionary:

  • Key → Country

  • Value → (sum_of_temp, count)

• Compute average

Sample Python Logic:

import csv
from collections import defaultdict

def average_temp(file_path):
    data = defaultdict(lambda: [0, 0])

    with open(file_path, 'r') as f:
        reader = csv.DictReader(f)
        for row in reader:
            country = row["Country"]
            temp = float(row["Temp"])
            data[country][0] += temp
            data[country][1] += 1

    result = {}
    for country, (total, count) in data.items():
        result[country] = round(total / count, 2)

    return result

Time Complexity:

O(n) — iterate once over CSV rows.

Space Complexity:

O(k) — where k = number of unique countries.

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Tree Path Problem

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Question 5: How many ways are there to reach A to A (top to bottom)?

(Referring to the triangular tree structure)

Understanding:

Each node splits into two children.
To reach bottom, at each level we have 2 choices.

If depth = n levels:

Total paths = 2^(n-1)

Approach:

Use recursion or mathematical formula.

Code:

def count_paths(levels):
    return 2 ** (levels - 1)

Time Complexity:

O(1) (mathematical approach)

If recursive traversal:
O(2^n)

Space Complexity:

O(1) (formula)
O(n) (recursion stack)

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Scenario-Based Question

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Question 6: Write test cases for File Upload Feature.

Scenario Summary:

• User enters URL

• Clicks "Choose" → Opens file picker

• Selects file → Path displayed in input

• Clicks "Upload" → File uploaded

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Positive Test Cases:

1. Upload valid file (allowed format)

2. Upload small size file

3. Upload max allowed size file

4. Upload supported file types (.pdf, .jpg, etc.)

5. Verify success message

6. Verify file stored correctly

7. Verify correct HTTP status code

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Negative Test Cases:

1. Upload unsupported file type

2. Upload file exceeding max size

3. Click Upload without choosing file

4. Expired session during upload

5. Network failure during upload

6. Corrupted file upload

7. Upload empty file

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Edge Cases:

1. Very large file near size limit

2. File name with special characters

3. Duplicate file name

4. Simultaneous uploads

5. Slow network upload

6. File path manually edited

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What to Validate:

• Status code

• Response body

• File integrity

• Security (no directory traversal)

• No sensitive data exposure

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Question 7: Tell me about your framework and folder structure.

Answer:

Structure:

project/
│
├── clients/
├── utils/
├── tests/
├── config/
├── resources/
├── schemas/
├── conftest.py
├── pytest.ini
├── Dockerfile
├── Jenkinsfile
└── requirements.txt

Design Principles:

• Reusable client layer

• Separation of concerns

• Config-driven execution

• CI/CD friendly

• Scalable for microservices

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Question 8: Any Challenges Faced?

Answer:

• Flaky tests due to timing

• Parallel execution conflicts

• Rate limiting

• Environment mismatch

• Logging inconsistencies

• Debugging distributed failures

Solutions included:

• Retry mechanisms

• Better abstraction

• Centralized logging

• Proper environment management

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Key Takeaways

• Round 3 focused more on structured thinking and depth.

• Strong fundamentals in Linux, Docker, Kubernetes are expected.

• Coding clarity matters.

• Test case design maturity differentiates senior candidates.

• Clear explanation > complex answers.

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