Common SDET Interview Questions for 2023 - IQCode's Top Picks

Understanding SDET

An SDET, which stands for Software Development Engineer in Test, is an expert in both development and testing within the IT industry. These professionals are involved in every aspect of the software development and testing process, with their expertise focused solely on testability, robustness, and performance. Moreover, they can contribute as a reviewer or contributor to the development of production software designs as well. Currently, many companies are looking to hire SDETs since they can assist with both software development and software evaluation. Therefore, SDETs are beneficial to companies as they can work on high-performance code or testing framework creation, thereby fulfilling two crucial job roles. Notably, Microsoft was the first to hire SDETs, but other businesses have taken notice and are nowadays seeking SDET experts to aid them in product development and testing design.

In this article, we'll cover some common interview questions for individuals seeking employment as Software Development Engineers in Test (SDETs). It is crucial for SDETs to have a solid understanding of software testing principles. Therefore, we'll also recommend reading some software testing interview questions to prepare thoroughly.

For new professionals seeking employment as SDETs, one of the most frequently asked interview questions is to differentiate between the roles of an SDET and a manual tester.

Code:

// Function to differentiate between an SDET and a manual tester
function differentiateRoles() {
  console.log("An SDET is a professional in development and testing, while a manual tester primarily handles software testing and not development.");
}

P: It is important for SDETs to have a strong understanding of software development and testing processes in order to be effective in their roles. SDETs can help companies by working on high-performance code and creating testing frameworks. Therefore, this makes them a valuable resource for businesses. When preparing for an SDET interview, it is also essential to study software testing principles thoroughly. If you are interested in obtaining a job as an SDET, we have provided some interview questions above to help you get started.

Understanding Ad-Hoc Testing

Ad-hoc testing is a software testing approach where the tester does not follow any predefined test plan or test cases. Instead, the tester would perform the testing process based on his/her knowledge, experience, and skills. Ad-hoc testing is usually performed when there is insufficient or no time to create a detailed test plan or test cases. It is used to find issues that may not be found by a predefined testing approach. Ad-hoc testing can be an effective way to discover issues that may be missed by other types of testing and is often performed by subject matter experts who have a deep understanding of the application under test.

Understanding Code Inspection in Software Testing

Code inspection, also known as peer code review, is a software testing technique that involves reviewing the code written by one or more developers to identify defects or errors. It is a type of static testing that does not require running the code.

The main advantages of code inspection include:

• Code inspection helps identify coding errors and defects early in the development process, reducing the cost of fixing them later.
• It promotes collaboration and knowledge sharing among team members, and it can lead to improved coding practices and standards.
• Code inspection helps ensure that the code complies with organizational and industry-specific coding standards and guidelines.
• It can increase the overall quality of the software and reduce the risk of software failures and bugs in production.

Overall, code inspection plays a crucial role in the development process, helping to identify errors, improve coding practices, and optimize the quality of the software.

Understanding Bug Reports in Software Testing

A bug report in software testing is a document that contains information about a defect or problem found in a software application during the testing process. It typically includes details such as the steps to reproduce the bug, the expected behavior, and the actual behavior observed. The bug report is usually created by a tester and submitted to the development team, who will then investigate the issue and work on fixing it. Bug reports play a crucial role in ensuring the quality of the software and improving its functionality.

Elements of a Bug Report

When reporting a bug, the following elements should be included:

- Summary: A brief and descriptive title for the bug.
- Description: A detailed description of the bug, including steps to reproduce it.
- Expected Result: What the user expected to happen when performing the actions.
- Actual Result: What actually happened as a result of performing the actions.
- Severity: The level of impact the bug has on the system or user experience.
- Environment: The browser, device, and operating system being used.
- Attachments: Screenshots, error messages, or other relevant files that can help reproduce or troubleshoot the bug.

// Example Bug Report

Title: Incorrect pricing on products page
Description: When visiting the products page and sorting by price, the sorting algorithm seems to be incorrect. I clicked on sort by price in ascending order, but the product at the top of the page had a higher price than a product in the middle. This behavior seems inconsistent and confusing for buyers.
Expected Result: Products should be sorted by price in the order specified.
Actual Result: Products are not sorted correctly and the ordering seems random.
Severity: High
Environment: Google Chrome Version 91.0.4472.124, Windows 10, Dell Latitude Laptop
Attachments: screenshot of products page, error message received

Do's and Don'ts for a Good Bug Report

When reporting bugs, it is important to provide clear and detailed information so that developers can replicate and fix the issue effectively. Below are some do's and don'ts to consider when writing a bug report:

• Do: Provide a specific and descriptive title for the bug report.
• Do: Include step-by-step instructions on how to reproduce the issue.
• Do: Provide information on the browser or device you were using.
• Do: Include screenshots or videos to help illustrate the issue.
• Do: Test to see if the issue occurs consistently or intermittently.
• Don't: Assume that the developer knows what you're talking about - provide as much detail as possible.
• Don't: Use technical jargon or acronyms that may not be familiar to everyone.
• Don't: Be rude or unprofessional in your bug report.

Roles and Responsibilities of a Software Development Engineer in Test (SDET)

A Software Development Engineer in Test (SDET) is responsible for creating and maintaining automated test cases that ensures the quality and reliability of software products. Some of the main roles and responsibilities of an SDET include:

- Developing and implementing test plans, test cases, and automation scripts - Collaborating with software developers, quality assurance engineers, product managers, and other stakeholders to identify and resolve issues - Conducting code reviews and making suggestions for improving code quality and test coverage - Participating in design and architecture reviews to ensure that new features are testable and scalable - Identifying opportunities to improve testing processes and strategies to reduce defects and improve overall software quality - Providing input into the development of new testing tools and technologies - Analyzing test results to identify trends and patterns, and making recommendations for further improvements - Staying up-to-date with industry trends and best practices in software testing and quality assurance.

Overall, an SDET focuses on ensuring that the software is thoroughly tested in an automated way and meets the established quality standards before being released to users.

Understanding Severity and Priority in Software Testing

Severity and priority are two important factors in software testing that are used to assess the impact and urgency of defects or issues found in the software application. Severity refers to the degree of impact that a defect has on the system's functionality or performance, while priority refers to the level of urgency with which the defect should be addressed.

Severity is typically measured on a scale of 1-5, with 1 being the most severe and 5 being the least severe. Defects that are characterized as level 1 are critical and have the potential to cause major system failures, while level 5 defects are minor cosmetic issues that do not impact system functionality.

Priority, on the other hand, is a measure of how quickly a defect needs to be resolved. Priority can be set by considering factors such as the business impact, the number of users affected, and how critical the system is to business operations. Issues that are assigned a high priority need to be addressed immediately, while those with lower priority can be deferred until other higher-priority issues are resolved.

It is important for testers to differentiate between severity and priority when reporting defects or issues to development teams, to ensure that critical issues are addressed in a timely manner and that less critical issues do not negatively impact overall system functionality.

Pseudocode:

def report_defect(severity, priority, description):
    if severity == 1 or priority == "High":
        notify_development_team(description, urgency_level="High")
    elif severity == 2 or priority == "Medium":
        notify_development_team(description, urgency_level="Medium")
    else:
        notify_development_team(description, urgency_level="Low")

Understanding Alpha Testing and its Objectives

Alpha testing refers to the phase of software testing that occurs before it is released to beta testing. The objective of alpha testing is to discover and fix any issues or bugs in the software while it is still in the development stage.

During alpha testing, a limited group of testers are given access to the software to use and provide feedback on its functionality and user experience. This testing typically takes place in a controlled environment and can involve both manual and automated testing methods. The feedback gathered during alpha testing helps to improve the software and prepare it for beta testing and ultimately release to the general public.

Objectives of alpha testing include identifying and fixing issues, ensuring the software meets its intended functionality, improving the user experience, and reducing the likelihood of bugs or issues occurring after release. Properly conducted alpha testing can save time and resources in the long run by identifying and addressing issues before they become widespread problems for users.

Understanding Beta Testing and Its Types

Beta testing is a type of software testing that enables real users to test the software and provide feedback before its official release to the public. It allows developers to identify and correct issues that may arise during usage and ensure that the software meets the expectations of the users.

There are three types of beta testing:

1. Closed Beta Testing: A select group of users test the software before it is released to the public. This allows for a more controlled testing environment and feedback can be collected from a specific target audience.

2. Open Beta Testing: The software is released to the general public for testing. This allows a wider range of users to test the software in different environments and provide feedback.

3. Beta Testing in the Wild: This type of beta testing involves releasing the software to a small subset of users without any instructions or support. This type of testing is useful for identifying issues that may not have been anticipated during development.

In conclusion, beta testing plays an important role in ensuring that software meets the expectations of the users by identifying and addressing any issues prior to release.

SDET Interview Question for Experienced: Alpha Testing vs Beta Testing

In software testing, Alpha testing is a type of pre-release testing carried out by the development team. It is executed in a lab environment and is supervised by the customer or an independent test team. This is usually done before beta testing.

On the other hand, Beta testing is performed by the end-users or customers at their own site. It is typically done after the completion of alpha testing. It is intended to find out the issues that were not found by the development team during alpha testing.

The main difference between these two types of testing is that alpha testing is done in-house while beta testing is done externally. Additionally, alpha testing aims to find defects before the product's release, while beta testing helps in identifying the remaining defects.

Popular Software Testing Tools and Their Key Features

1. Selenium: Open source automation tool that allows testing of web applications across different platforms and browsers.

2. JMeter: Open source load testing tool that measures performance and load test functional behavior of web applications.

3. Appium: Open source automation tool for testing native, hybrid, and mobile web applications for both iOS and Android platforms.

4. SoapUI: Open source testing tool that evaluates API functionality and performs web service testing.

5. TestComplete: Commercial automation tool for testing desktop, mobile, and web applications.

6. HP Unified Functional Testing (UFT): Commercial automation tool that allows testing of functional and regression tests for desktop, mobile, and web applications.

7. IBM Rational Functional Tester (RFT): Commercial automation tool for testing Java, Windows, web-based, and .NET applications.

Some of the key features of these tools include cross-browser compatibility testing, load and performance testing, mobile and web automation testing, and functional and regression testing. These tools have become vital in the software industry for delivering high-quality software products with improved efficiency and reduced costs.

Understanding Performance Testing and Load Testing and Their Differences

Performance testing and load testing are two important processes within software testing. Performance testing is the process of evaluating the responsiveness, speed, reliability, and stability of a software application under a certain workload and determining if it meets the required performance criteria. It helps to assess if the system is working well or not, in terms of stability and speed in relation to user requests and responses.

On the other hand, load testing is a type of performance testing that focuses on assessing the system's behavior under a high load. Load testing checks how the system performs within the specified limits of the hardware capacities, by subjecting it to the anticipated load during peak operating times. Load testing is performed to ensure that the system can handle the expected load and provide users with satisfactory performance quality.

Therefore, the main difference between performance testing and load testing is that performance testing is focused on testing the system's evaluation under specific performance criteria, while load testing is mainly focused on measuring how the system performs under a specified high load to ensure it can handle it.

// Code Example - Performance Testing 
test("checks if the application meets performance criteria", () => {
  // simulate a specific workload 
  // evaluate the response time 
  // check the stability of the system 
  // compare the results with requirements 
  // assert if the application meets the performance criteria 
});

// Code Example - Load Testing 
test("checks if the application can handle the anticipated load", () => {
  // simulate a high load 
  // assess how the system behaves under load 
  // determine the maximum load capacity 
  // compare the results with the specified limits 
  // assert if the application can handle the expected load 
});

Expert Opinions on Determining Product Readiness for Live Environment

The following are some expert opinions on how a tester can determine whether a product is ready to be used in a live environment:

1. Conduct thorough testing: A tester should conduct extensive testing of the product's functionality, usability, performance, security, and compatibility with various systems. This will help in identifying any defects or issues that could impact the product's performance in a live environment.

2. Use automation tools: Automation tools can help in conducting repetitive and time-consuming tasks such as regression testing, load testing, and performance testing. Automation can also help in detecting issues that are not visible to manual testing.

3. Involve end-users: It is important to involve end-users in the testing process to get feedback on usability and functionality. This will help in identifying any issues that end-users may face while using the product in a live environment.

4. Review test results: A tester should review all the test results to identify any patterns or trends in defects. This will help in prioritizing the defects based on their severity and impact on the product's performance.

5. Use real-time monitoring: Real-time monitoring can help in detecting any issues that occur in a live environment. This will help in addressing issues immediately before they impact the end-users.

In conclusion, a tester should conduct thorough testing, use automation tools, involve end-users, review test results, and use real-time monitoring to determine whether a product is ready to be used in a live environment.

Understanding Risk-Based Testing

Risk-based testing is an approach where the testing effort is focused on the areas of the product or software that present a higher level of risk. The main goal of risk-based testing is to identify and prioritize the features or functions of the product that are crucial to the user, business, or system requirements. This approach helps ensure that the most critical parts of the product are thoroughly tested, reducing the probability of defects, failures, and critical impacts.

Risk-based testing involves the following steps:

1. Identify and analyze all the potential risks related to the product or software under test. 2. Prioritize the risks based on their impact, likelihood of occurrence, and severity of consequences. 3. Define the testing scope and objectives based on the identified risks. 4. Plan, design and execute the tests that best cover the high-risk areas of the product. 5. Monitor and control the testing process to ensure that testing meets objectives and goals.

By using risk-based testing, testers can optimize testing efforts, reduce costs and improve the quality of the software products. They can also ensure that the software meets the expected requirements, functions properly, and provides a satisfactory user experience.

Equivalence Partitioning and its Working

Equivalence partitioning is a software testing technique that involves dividing input data into groups. The purpose of this technique is to reduce the time and effort required for testing while still providing sufficient coverage. The premise of this technique is that if a software program works correctly for one input group, it will work for other inputs within the group. Additionally, if one input group causes the program to fail, all other inputs within the same group will also fail.

Let's consider an example of a login screen for a web application that requires an email address and a password. The email address must be a valid format, and the password must meet specific criteria to be considered valid. We can use equivalence partitioning to divide the input data into three groups:

1. Invalid email addresses, such as an email address without '@' or domain in the end, are grouped together.
2. Valid email addresses that are registered but incorrect passwords are grouped together.
3. Valid email addresses with correct passwords are grouped together.

So by merely testing one input value from each of these groups, we can get sufficient test coverage. Suppose we test a valid email address with an incorrect password and the program displays an error message. In that case, we know that all other inputs within that group (valid email address with an incorrect password) will also lead to an error. By using equivalence partitioning, we can ensure that we test the critical inputs without wasting time and resources on unnecessary testing.

Creating Automation Strategy for a Product without Automation Tests

When creating an automation strategy for a product that doesn't have any automation tests, we need to follow the steps mentioned below:

1. **Analyze the product:** We need to analyze the product thoroughly to determine the most critical areas that need to be automated.

2. **Choose the right framework:** Depending on the technology used in the product, we need to select the right automation framework that would work for the application.

3. **Create a Test Plan:** Based on the analysis, we need to create a test plan that covers all the critical areas of the product that need to be automated.

4. **Select the right Automation tools:** Based on the selected automation framework, we need to choose the right automation tools that would best suit our requirements.

5. **Write Automation Scripts:** With the tools in place, we can go ahead and write automation scripts to automate the selected areas of the product.

6. **Execute Automation Scripts:** Once we have written the automation scripts, we need to execute them to ensure that they work as expected.

7. **Integrate with CI/CD pipelines:** We can then integrate the automation scripts with the CI/CD pipeline to ensure that they are run automatically every time there is a new build.

8. **Monitor and Maintain:** Finally, we need to monitor the automation scripts and maintain them to ensure that they continue to work as expected.

By following these steps, we can create a robust automation strategy for a product that does not have any automation tests.

Would You Sacrifice Thorough Testing for a Quick Product Release?

As an artificial intelligence language model, I do not have personal preferences or beliefs. However, from a professional standpoint, it is not recommended to compromise on the thoroughness of testing for the sake of releasing a product quickly. Thorough testing ensures the reliability, performance, and security of a product, and releasing a product with known issues or bugs can lead to negative consequences such as loss of customer trust and revenue. It is always better to take the time to test a product thoroughly before releasing it to the market.

Testing Technique for Urgent Hotfix Deployment

If a crucial hotfix must be deployed urgently, the most appropriate testing technique would be regression testing. Regression testing involves testing the software to ensure that any new changes or fixes do not have unintended consequences or negatively impact existing features. It is the most suitable technique in such a scenario since it focuses on identifying any defects that may have been introduced because of the changes made. With this technique, the testing team can quickly determine if the hotfix is effective and if any other issues have been introduced into the software as part of the fix. Additionally, exploratory testing can also be used to complement the regression testing process by allowing the testing team to rapidly identify and report any issues that might have been missed in the regression testing process.

Understanding Fuzz Testing and the Types of Bugs it Detects

Fuzz testing, also known as fuzzing, is a software testing technique that involves providing invalid, unexpected, or random data inputs to a software application. The main aim of this technique is to find vulnerabilities or software bugs that may cause the system to crash or fail under certain circumstances.

There are several types of bugs that can be detected through fuzz testing, including memory leaks, buffer overflows, null pointer dereferences, and format string vulnerabilities. These bugs can pose significant security risks, as they can potentially be exploited by malicious attackers to gain unauthorized access to a system or cause it to malfunction.

It is important for software developers to employ fuzz testing as a part of their software testing process to ensure that their applications are robust and free from vulnerabilities that may cause any threat to the users or the system. By detecting and fixing bugs before software deployment, software developers can save resources and reduce the risk of potential security breaches.

Understanding Test Scripts and Differentiating between Test Case and Test Script

A test script is a set of instructions for testing a particular feature or functionality of a software application. It outlines the steps that testers need to take to perform a series of checks, and the expected results that they should see if the application behaves correctly.

A test case, on the other hand, is a set of requirements that need to be tested, along with the inputs, actions, and expected outcomes required to verify that these requirements are fulfilled.

The key difference between the two is that a test case is a more abstract concept, while a test script is specific to a particular test scenario. In other words, a test case outlines the overall requirements that need to be tested, while a test script provides detailed instructions for testing one portion of those requirements in a structured and repeatable way.

Difference between Walkthrough and Inspection

Walkthrough and Inspection are two different techniques used in software testing. Walkthrough is an informal process, whereas inspection is a more formal process.

In a Walkthrough, the developer guides the participants through the code, giving them an overview of the code and its functionality. The purpose of a walkthrough is to identify defects in the code and to obtain feedback from the participants. The participants are usually team members, and the walkthrough can be conducted at any stage of the software development process.

On the other hand, Inspection is a formal process in which a team of reviewers examines the code in detail. Inspection typically involves a structured process and follows predefined rules. The purpose of an inspection is to identify defects in the code and to ensure that the code meets the project requirements. The participants in an inspection are usually experts in the domain, and the inspection is typically conducted at the end of the code development.

In summary, while both walkthrough and inspection are used to identify defects in the code, the main differences between them are their formality, the level of detail, and the timing.

Understanding White Box Testing and Black Box Testing

White box testing and black box testing are two testing techniques used in software development to ensure software quality.

White box testing: It is also known as clear box testing, glass box testing or structural testing. White box testing is performed on the internal logic and structure of the code, as the testers have complete knowledge of the code and are able to understand and test each and every line of code. The main goal of white box testing is to verify the code's functionality and ensure that it conforms to the design specifications.

Black box testing: It is also known as functional testing or behavioural testing. Black box testing is performed on the external interface of the software - the inputs and outputs - without considering the internal code structure, design or implementation details. The testers do not have any knowledge of the internal workings of the software. The main goal of black box testing is to check whether the software fulfills its intended requirements and specifications.

Differences between white box testing and black box testing:

White box testing	Black box testing
Tests internal workings of software	Tests external interface of software
Testers have complete knowledge of code	Testers have no knowledge of code
Verifies code functionality and conforms to design specifications	Verifies whether software fulfills intended requirements and specifications
Appropriate for unit testing and code coverage	Appropriate for system testing and user acceptance testing

In summary, white box testing focuses on the internal workings of the software, while black box testing focuses on the external interface and user experience with the software. Both techniques are important for ensuring the overall quality of the software.

Swap Two Variables Without Third Variable

// Initialize variables x and y
int x = 5;
int y = 10;

// Print initial values of x and y
System.out.println("Before Swapping");
System.out.println("Value of x: " + x);
System.out.println("Value of y: " + y);

// Swap values without third  variable
x = x + y;
y = x - y;
x = x - y;

// Print swapped values of x and y
System.out.println("After Swapping");
System.out.println("Value of x: " + x);
System.out.println("Value of y: " + y);

In the above code snippet, two integer variables named 'x' and 'y' are initialized. The values of these variables are swapped without using a third variable. Finally, the new values of 'x' and 'y' are printed.

Reverse Number Program

// This program takes an input number from the user
// and reverses the digits of the number.

#include <iostream>
using namespace std;

int main()
{
    int number, reverse = 0, remainder;

    cout << "Enter any number: ";
    cin >> number;

    // reversing the number
    while (number != 0)
    {
        remainder = number % 10;
        reverse = (reverse * 10) + remainder;
        number /= 10;
    }

    cout << "The reverse of the number is: " << reverse << endl;

    return 0;
}

In this program, we take an input number from the user and store it in the 'number' variable. We then use a 'while' loop to continuously extract the last digit of the number using the modulus operator and add it to the 'reverse' variable. Once all the digits have been extracted, we print the 'reverse' variable which contains the reversed number.

Checking the balance of pairs and ordering of characters in an Expression

The following program checks whether the expression string has balanced pairs and ordering of (), [], and "" characters or not.

def is_balanced(expression):
    stack = []
    for char in expression:
        if char in ["(", "[", "\"", "'"]:
            stack.append(char)
        elif char in [")", "]", "\"", "'"]:
            # if stack is empty and current char is closing brackets, return false
            if not stack:
                return False
            # check if current char is closing of opening bracket
            if char == ")" and stack[-1] == "(":
                stack.pop()
            elif char == "]" and stack[-1] == "[":
                stack.pop()
            elif char == "'" and stack[-1] == "'":
                stack.pop()
            elif char == "\"" and stack[-1] == "\"":
                stack.pop()
            else:
                return False
    # if stack is not empty, return false
    if stack:
        return False
    return True

expression = input("Enter the expression: ")
if is_balanced(expression):
    print("Expression is balanced")
else:
    print("Expression is not balanced")

Program to Print Factorial of a Given Input Number

#include <stdio.h>

int main() {
    int input, factorial = 1;

    printf("Enter a positive integer: ");
    scanf("%d", &input);

    // calculate factorial of input number
    for (int i = 1; i <= input; i++) {
        factorial *= i;
    }

    printf("Factorial of %d is %d", input, factorial);
    return 0;
}

Explanation:

The above program prompts the user to enter a positive integer and then calculates its factorial using a for loop. The variable "factorial" initially has a value of 1, and its value is multiplied by each integer from 1 to the input number, giving the final result of the factorial. The value of the factorial for the given input is then printed as the output.

Determining the Existence of a Triplet in an Array that Equals the Given Value

function isTripletExist(array, value) {
  let len = array.length;

  // Sort array in ascending order
  array.sort(function (a, b) {
    return a - b;
  });

  for (let i = 0; i < len - 2; i++) {
    // Initialize left and right pointers
    let left = i + 1;
    let right = len - 1;

    while (left < right) {
      if (array[i] + array[left] + array[right] === value) {
        console.log("Triplet is", array[i], ",", array[left], ",", array[right]);
        return true;
      }
      else if (array[i] + array[left] + array[right] < value) left++;

      else right--;
    }
  }

  return false;
}

// Example
let arr = [1, 4, 45, 6, 10, 8];
let val = 22;
let result = isTripletExist(arr, val);
console.log(result);//Expected output: true

This function takes two parameters: an array of numbers and a target value. It returns a Boolean value indicating the existence of a triplet that sums up to the target value in the given array. If such a triplet exists, the function prints out the triplet and returns true. Otherwise, it returns false.

The function first sorts the input array in ascending order using the `Array.sort()` method. This sort is important to ensure that the left and right pointers remain in the correct order.

Then, the function loops through the array from 0 to `len-2`. For each array element `array[i]`, the function initializes left and right pointers such That `left=i+1` and `right=len-1`.

Finally, the function compares the sum of the triplet `(array[i],array[left],array[right])` with the target `value`. If the sum is greater than the target value, the right pointer is decremented by 1. Otherwise, the left pointer is incremented by 1.