Dunnhumby Senior Software Tester Interview Questions and Answers

Q1. Java hash map and how it works
Ans. 
Java hash map is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values based on keys.
• HashMap in Java implements the Map interface and allows null keys and values.

• It uses hashing to store and retrieve key-value pairs, providing O(1) time complexity for get() and put() operations.

• Example: HashMap map = new HashMap<>(); map.put("key", 1); int value = map.get("key");
Answered by AI
Add your answer

Q1. Questions related to SAP BW and HANA
Add your answer

Q1. Questions related to SAP BW and HANA
Add your answer

Q1. Reason for Job Change
Add your answer

90 min coding test with 4-5 problems to solve

Q1. Technical rounds mostly goes around the project work ans some were based on the JD.
Add your answer

Q1. Basic QA related Questions
Add your answer

Q1. Gave case study based on java scheduler
Add your answer

Q1. Gave programming question to solve
Add your answer

Q1. Typical HR questions
Add your answer

Prepare well on coding n programming

Topic will be give should talk for a min

Q1. What is the difference between List and Tuple?
Ans. 
List is mutable and Tuple is immutable in Python.
• List can be modified after creation while Tuple cannot be modified.

• List uses square brackets [] while Tuple uses parentheses ().

• List is used for homogenous data while Tuple is used for heterogenous data.

• List is slower than Tuple in terms of performance.

• Example of List: [1, 2, 3] and Example of Tuple: (1, 'hello', 3.14)
Answered by AI
View 1 more answer
Q2. What is __init__ ? Follow up question why is __ (double underscore) used?
Add your answer
Q3. A SQL query based on group by and order by DESC LIMIT 1 in order to fetch highest row of a group in a dataset given by panelist.
Add your answer
Q4. A simple query on SQL using group by and aggregate function.
Add your answer
Q5. Panelist asked about my previous work experience and projects I worked upon earlier and the technologies used.
Add your answer
Q6. Question on how do we create table using SQL Alchemy in Flask (since I had used Python Flask in one of my previous projects and had highlighted it pretty well on my resume).
Add your answer
Q7. How is memory managed in Python?
Ans. 
Python uses automatic memory management through garbage collection.
• Python uses reference counting to keep track of memory usage.

• When an object's reference count drops to zero, it is deleted.

• Python also uses a garbage collector to handle circular references.

• Memory allocation is handled by the Python memory manager.

• Python provides tools like the 'gc' module for managing memory usage.
Answered by AI
Add your answer

Q1. Question on List operation.
Add your answer
Q2. Do you know numpy pandas?
Ans. 
Yes, numpy and pandas are Python libraries used for data analysis and manipulation.
• NumPy is used for numerical operations on arrays and matrices.

• Pandas is used for data manipulation and analysis, providing data structures like DataFrame.

• Both libraries are commonly used in data science and machine learning.

• Example: import numpy as np; import pandas as pd;
Answered by AI
Add your answer
Q3. A question to count number of times a letter occurs in a sentence and then also find the maximum occurring letter.
Add your answer
Q4. Difference between generator and iterator?
Ans. 
Generator generates values on the fly while iterator iterates over a collection of values.
• Generator is a function that returns an iterator.

• Generators use 'yield' keyword to return values one at a time.

• Iterators are objects that implement the 'next' method to return the next value in a collection.

• Iterators can be created from arrays, strings, maps, sets, etc.

• Generators are useful for generating large sequences of values...read more
Answered by AI
Add your answer
Q5. What is the selling point about you why should we consider you over other candidate?
Add your answer

Q1. Why are you looking for a change?
Add your answer
Q2. What are your salary expectations?
Add your answer