Tech Mahindra ETL Test Engineer Interview Questions and Answers

A constructor is a special type of method in a class that is automatically called when an object of that class is created.

• Constructors have the same name as the class they belong to

• They are used to initialize the object's state or perform any necessary setup

• Constructors can have parameters to customize the initialization process

• Example: public class Car { public Car(String color) { this.color = color; } }

Yes, a static method can be overridden in Java using the concept of method hiding.

• In Java, static methods cannot be overridden in the traditional sense like instance methods.

• When a subclass defines a static method with the same signature as a static method in the superclass, it is called method hiding.

• Method hiding does not follow polymorphism and is resolved at compile time based on the reference type.

• Example: class...read more

Yes, a static local variable can be created inside a static method.

• Yes, a static local variable can be declared inside a static method in programming languages like C++.

• Static local variables retain their values between function calls.

• Example: static void myStaticMethod() { static int count = 0; count++; }

String memory allocation is dynamic and depends on the length of the string.

• String memory allocation is dynamic and can change based on the length of the string.

• In Java, a String object is stored in the heap memory.

• Each character in a String typically takes up 2 bytes of memory.

• String objects in Java are immutable, meaning once a String object is created, it cannot be changed.

Yes, you can create a static method inside an abstract class or interface.

• Static methods can be defined in interfaces since Java 8.

• Static methods in interfaces are used for providing utility methods that are not tied to any specific instance of the interface.

• Static methods in abstract classes can be used for common functionality that does not require an instance of the class.

The parent class of Java is the Object class.

• All classes in Java are directly or indirectly derived from the Object class.

• The Object class is the root class in Java's class hierarchy.

• It provides methods that are common to all objects in Java, such as toString(), equals(), and hashCode().

Window Handles in Selenium are unique identifiers used to handle multiple browser windows in a Selenium test script.

• Window Handles are unique alphanumeric strings assigned to each browser window opened by Selenium.

• They are used to switch between different browser windows during a test script execution.

• Window Handles can be obtained using getWindowHandles() method in Selenium.

• Example: Set handles = driver.getWindowHandl

Java OOPs concepts are used in automation framework design for better code organization and reusability.

• Encapsulation: Used to hide the internal implementation details of classes and provide access through methods.

• Inheritance: Allows for code reuse by creating parent-child relationships between classes.

• Polymorphism: Enables methods to behave differently based on the object they are called on.

• Abstraction: Helps in defin...read more

OTP can be handled by generating, sending, and verifying it in automated tests.

• Generate OTP using a random number generator

• Send OTP to the user via email, SMS, or any other communication channel

• Verify OTP entered by the user against the generated OTP

To start Appium in automation, you need to install Appium server, set up desired capabilities, and run the server.

• Install Appium server using npm install -g appium

• Set up desired capabilities in your test script

• Start the Appium server using the command appium

Types of mobile apps include native apps, web apps, and hybrid apps.

• Native apps are developed for specific platforms like iOS or Android

• Web apps are accessed through a web browser and do not need to be downloaded from an app store

• Hybrid apps combine elements of both native and web apps

• Examples include Instagram (native), Twitter (web), and Uber (hybrid)

Program to remove duplicate letters in a string

• Iterate through the string and keep track of seen characters in a set

• Append characters to a new string only if they are not already in the set

• Return the new string without duplicate letters

Swipe action in mobile devices can be performed using swipe() method in Appium or TouchAction class in Selenium.

• Use swipe() method in Appium to perform swipe action in mobile devices

• Alternatively, use TouchAction class in Selenium for swipe action

• Specify the start and end coordinates for the swipe action

• Adjust the duration and speed of the swipe as needed

Java program to print sum of digits from a given string

• Iterate through each character in the string

• Check if the character is a digit using Character.isDigit() method

• Convert the digit character to integer using Character.getNumericValue() method

• Sum up all the digits found in the string

OOPs concepts used in the framework include inheritance, polymorphism, encapsulation, and abstraction.

• Inheritance is used to create a parent-child relationship between classes. For example, a base class 'Page' can be inherited by 'HomePage' and 'LoginPage' classes.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass. For instance, a 'click' method can be implemented different...read more

Polymorphism is the ability of a single function or method to operate on different types of data.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example of compile-time polymorphism: function overloading in Java.

• Example of runtime polymorphism: method overriding in Java

Java program to print the sum of elements in a string array.

• Convert each element in the string array to an integer using Integer.parseInt()

• Sum up all the integers to get the total sum

Reverse a string using Java program and handle stale element in Selenium

• Create a Java program to reverse a string using StringBuilder or char array

• In Selenium, handle stale element exception by refreshing the element or using WebDriverWait

• Example: Java program - input: 'hello', output: 'olleh'; Selenium - handle stale element by refreshing the element before interacting with it

My expected salary is based on my experience, skills, and the market rate for Automation Test Engineers.

• I have researched the average salary range for Automation Test Engineers in this location.

• I am looking for a competitive salary that reflects my expertise in automation testing.

• I am open to negotiation based on the overall compensation package offered.

Drop command deletes the table structure along with data, while truncate command deletes only the data.

• Drop command removes the table structure and all its data, while truncate command only removes the data but keeps the table structure intact.

• Drop command is a DDL (Data Definition Language) command, while truncate command is a DML (Data Manipulation Language) command.

• Drop command is slower than truncate command as it ...read more

In my project, I perform validations such as data completeness, data accuracy, data transformation, and data integrity checks.

• Data completeness checks to ensure all required fields are populated

• Data accuracy checks to verify the correctness of data

• Data transformation checks to validate the transformation rules are applied correctly

• Data integrity checks to maintain data consistency and reliability

Star Schema is a type of database schema where a central fact table is connected to multiple dimension tables. Snowflake Schema is a normalized form of Star Schema where dimension tables are further normalized into sub-dimension tables.

• Star Schema has a central fact table connected to multiple dimension tables

• Snowflake Schema is a normalized form of Star Schema with sub-dimension tables

• Star Schema is denormalized for b...read more

Fact tables contain quantitative data while dimension tables contain descriptive attributes.

• Fact tables store measurable, quantitative data such as sales revenue or quantity sold

• Dimension tables store descriptive attributes related to the data in the fact table, such as product name or customer details

• Fact tables are typically normalized while dimension tables are denormalized for easier querying

• Example: In a sales dat...read more