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Top 25 SDET Interview Questions

By sharing the skills and attributes of a developer as well as a tester, SDETs are highly skilled professionals who are competent in Software Development as well as Quality Engineering.

This means that a Software Development Engineer in Test is certainly in high demand in organizations cutting across sectors. Consequently, the desire to ace SDET Interviews has emerged as an aspiration of a majority of tech personnel.

A carefully drawn list of SDET Interview Questions can certainly be of huge help if you, too, are desirous of making it through an SDET Interview.

In this blog, we will focus on some of the key areas that are usually touched upon in SDET Interview Questions. We will also try to look at some of the Amazon SDET Interview Questions as well as Apple SDET Interview Questions. Accordingly, this article provides you with a valuable list of SDET Interview Questions and Answers, which can certainly be helpful to you as an SDET aspirant.

If you wish to read about the professional roadmap that one can opt for as he aspires for an SDET career, refer to our blog on How to Become a QA Automation Tester.

Basic SDET Interview Questions

What is the difference between SDET and Manual Testers?

This is one of the most common SDET Interview Questions.

sdet interview questions vs tester interview questions

Explain the difference between Severity and Priority.

Severity pertains to the effect that a specific defect in the form of a bug can have on a customer’s business. It measures the degree of impact that the issue will have on the system. Severity can be critical, major or minor.

Priority pertains to how important it is to fix the bug. Depending upon the degree of potential severity, developers assign priority to different defects, which are then sought to be resolved in a definite order. Thus, priority is essentially the order in which the bug is addressed. Priority can be high, medium, or low.

What is Exploratory and Ad hoc Testing?

  • Exploratory Testing: Under this type of testing, the tester does not have knowledge of the requirements and they carry out the test simply on the basis of exploring the functionalities of an application. Exploratory testing is executed by domain experts.
  • Ad hoc Testing: This type of testing falls under the informal category. It is executed without any prior documentation, planning, or adherence to any specific test design technique. It is conducted randomly when testers have a good amount of knowledge about the Application Under Test (AUT). There are no expected results, business requirement documents, or test cases.

What are the professional responsibilities of an SDET?

This is yet another of the classic SDET Interview Questions. The roles and responsibilities of a SDET include:

  • As an SDET Engineer, SDET happens to be involved in data design, product design and user interfaces
  • As a customer spokesperson, SDET strives to understand the requirement for a product from the perspective of the customer, and since they are involved at every stage of its development till its final release, they are the best advocate who can justify the need of the software
  • Automation solutions: SDETs are required to build high-quality and robust test automation solutions for performance, functional, and regression testing
  • Functional and non-functional testing: SDETs contribute to both functional and non-functional areas of testing. This means that they pay attention to the functionality as well as other aspects as the security of the application, the absence of any hacks that might be misused, and so on
  • Important channel of communication: SDETs are responsible for investigating customer products that are referred by the technical support team.
  • Designing: SDETs are also involved in architectural design discussions and help in providing effective feedback
skills required during an sdet interview

What is Alpha and Beta Testing?

  • Alpha Testing: This testing is conducted by testers in order to identify the presence of any bugs before the application is released into the live environment.
  • Beta Testing: Technical Beta testing is conducted by the end-users in a real environment who happen to be the actual users of the application.

What is Risk-Based Testing?

Risk-based testing refers to the type of test that involves testing the functionalities of a product on the basis of the priority of the deliverables. The criterion of business requirement is taken as the yardstick which helps in determining the priority of all functionalities of a product.

Accordingly, the high-priority functionalities which are supposed to have the highest business impact are tested first. These are followed by medium and low-priority functionalities. This testing is usually undertaken when there is lack of time for testing all the functionalities.

Explain Code Inspection.

Code Inspection can be regarded as a formal kind of review which provides safeguard against the development of a possible defect at a later point. It permits the programmer to take the help of a group in reviewing their source code. This group analyzes the code and questions the programmer on the logic of the code. This kind of prior review helps in verifying code standards and provides a check against common programming errors.

sdet interview questions about code inspection

What are the qualities of a good bug report?

The elements of a good bug report are:

  • It should elaborate on a single problem and should provide precise, clear and relevant information
  • It should provide a descriptive summary of the bug
  • Along with providing environment information, it should include the steps for reproducing the bug
  • It should also provide information on the real and expected behavior of the bug

What is the difference between Quality Assurance and Quality Control?

The difference between Quality Assurance and Quality Control is largely in terms of the fact that the former emphasizes upon the process of quality; while the latter emphasizes upon the quality of the output.

Quality Assurance is a preventive strategy which lays stress on planning, documenting and agreeing upon a definite set of guidelines which are necessary for ensuring quality. It is undertaken at the beginning of a project and the objective is to obstruct defects from entering into the solution in the first place.

Quality Control is a reactive strategy that includes all activities aimed at determining the quality of the delivered solutions. It helps in verifying the conformance of the output quality with the specified quality standards.

difference between Quality Assurance and Quality Control

What is Fuzz Testing?

Fuzz Testing is the process of identifying security loopholes and coding errors as well as locating hackable software bugs. It is carried out by injecting a large amount of random, incorrect and inadvertent data into the system in order to make it crash and then identify if anything breaks into the system.

Senior SDET Interview Questions

If the proper documentation for testing does not exist, what will you do?

There might be a situation wherein proper documentation is not available for test cases and still the tester is required to execute the test case. In such a situation, the tester might refer to some earlier mail provided by the client which describes all the requirements clearly.

Additionally, he might also refer to the screenshots where the details of the changes are mentioned or any verbal communication with the client which would help to understand the exact functionality of the changes needed.

How can a tester decide that a product is ready to be moved into the live environment?

The decision to move a product into the live environment is a crucial one. It is jointly undertaken by testers, developers as well as the higher management. Thus, they do take certain things into consideration in order to ensure that the product delivery is bugless.

  • Validation of bug reports handed over by the testers. It specifies the way in which the bug got resolved and whether retesting was performed by the tester
  • Validation of the entire set of test cases, which were written by the tester for that specific documentation and functionality
  • Execute automated test cases to make sure that new functionalities do not hamper the existing ones
  • Validation of test coverage report, which is important to ensure the coverage of all developing components
software development lifecycle

If the tester demands a specific bug report format, what can he do?

If the tester is asked for a specific format of the bug report, he can follow a conventional approach wherein the report contains the following elements:

  • Bug Summary
  • Reproduce Steps
  • Expected and Current Behavior of One Specific Bug

Explain the difference between Code Walkthrough and Code Inspection.

Code Walkthrough can be regarded as an informal review that is undertaken in an informal meeting. The author describes the work product to his supervisor or his peers in order to acquire feedback. The purpose is to check the validity of the product. It is often considered to be a static method of quality assurance.

Code Inspection is a formal review undertaken to ensure a product’s compliance with specific requirements and standards. It is initiated by the project team, involves fixed meetings, and compares the product with specific documents, code, and artefacts. It includes systematic and structured testing, which improves a software product’s availability, maintainability, and reliability.

How do you test text boxes without changing their backgrounds?

This can be performed without passing any data like:

  • Special Characters
  • Size of the Text Field
  • Alphanumeric Values
  • Minimum/Maximum Characters
  • Text Format

SDET Coding Interview Questions

How to reverse a string in Java?

A String can be reversed in Java by adopting different ways like:

  • Using StringBuilder Class
  • Using StringBuffer Class
  • Convert String into Character Array and use For Loop
  • Using Array List

Differentiate between Array and ArrayList in Java.?

Write a program to swap two numbers without using their temp variable.

The program to swap two numbers without using the temp variable is shown below:

public class swap{
public static void main (String args[])
int x = 50;
int y =60;
System.out.println(?Numbers before swapping?);
System.out.println(? number x is ? + x);
System.out.println(?number y is ? +y);
// Swapping numbers
x= x+y;
System.out.println(?Numbers after swapping?);
System.out.println(? number x is ? + x);
System.out.println(?number y is ? +y);

Write a program to reverse a number in any language.

The program to reverse a number in any language is given below:

public class reverseNumber {
public long reverse(long num)
long temp=0;
return temp;
public static void main(String args[])
long n= 342619;
reverseNumber inp = new reverseNumber();
System.out.println(?Given number is ?+ n);
System.out.println(?Reverse of given number is ?+inp.reverse(n));

Amazon SDET Interview Questions? Apple SDET Interview Questions

While Amazon is an e-commerce giant, Apple happens to be one of the world’s largest technology companies by revenue. Acquiring a job in either of these two companies is definitely a dream aspiration for many.

Similarly, these two companies have openings for SDETs, as well. If you, too, happen to be someone who is looking to make it through an SDET technical interview in these companies, the Amazon SDET Interview Questions and the Apple SDET Interview Questions mentioned here would definitely be of huge help.

Determine if two binary trees are identical.

This happens to be one of the typical SDET Interview Questions as part of the technical round.

As part of the problem statement, you will be provided with the roots of two binary trees. Identical trees happen to be those which have the same data and layout at each node. You should also remember that having the same data, doesn’t necessarily make the trees identical. It is important to consider their structure as well.

The given problem can be addressed recursively. The base case of recursion for framing the solution for this is if two compared nodes are null or one of them is null.

Thus two trees (Y and Z) are identical if:

  • Data on their roots is same or both roots are null
  • The left sub-tree of Y is identical to the left sub-tree of Z
  • The right sub-tree of Y is identical to the right sub-tree of Z

You can proceed with simultaneously using depth-first traversal on both trees and then keep comparing the data at each level.

identical binary trees

Write an efficient program to convert a binary tree into its mirror.

You will be provided with the root node of a binary tree and you must swap the left and right children for each node. The objective is to make use of bottom up mirroring and depth first traversal in order to mirror the nodes of a binary tree.

You can do a post order traversal of the binary tree. This would require you to swap the left and the right child for every node. Depth-First Traversal/Search (DFS) can be used in order to ensure that before returning from a node, all its children have been visited (and mirrored).

Find the palindrome substrings of a given string.

In case of this problem, you will be required to find all non-single letter substrings that are palindromes. For each letter in the input string, you can begin with expanding to the left and right while checking for even and odd length palindromes. You have to move to the next letter if you see that a palindrome does not exist. We can begin by expanding one character to the left and the right and compare. If both happen to be equal, you print out the palindrome substring.

Determine if the sum of any three integers in an array is equal to the given value.

In order to solve this problem, you will be required to sort the array. You will be required to fix one element e and find a pair (a, b) in the remaining array so that required_sum ? e is a+b.

 You can begin with the first element e in the array and try to find such a pair (a, b) in the remaining array (i.e., A[i + 1] to A[n-1]) which satisfies the condition: a + b = required_sum ? e. If you happen to find the pair, it means that you have found the solution: a, b and e. Consequently, you can stop the iteration.

On the other hand, if you do not find the pair, then you will have to repeat the steps for all elements e at index i=1 to n-3 until we find the specific pair which meets the condition.

Write an algorithm for reversing words in a string.

The objective of this question is to reverse the words in a string which is a sentence (an array of characters). You need to take note of the way in which the words are separated by whitespaces. The solution for this problem usually follows two steps. First you will be required to reverse the string. Then you will be required to traverse the string and reverse each word in its place.

Write a program to clone a directed graph.

The objective of this problem would be to clone a directed graph and print an output graph using depth first traversal and hash table. As you receive the root node of a directed graph, you can begin by cloning the graph by creating a deep copy. Consequently, the cloned graph will have the same vertices and edges.

You can begin with creating a copy of each node while traversing the graph, through depth first traversal. Each of the completed node can be stored in a hashtable so that there would be no need to revisit the nodes which exist in the hashtable. The hashtable key will be a node in the original graph, and its value will be the corresponding node in the cloned graph.


By the end of this blog, I am pretty sure that you must have acquired a fair idea of some of some of the most important topics which are continuously referred to as a part of SDET Interview Questions.

This list of SDET Interview Questions and Answers is definitely by no means exhaustive. However, it has been carefully curated to guide you and even give you a sense of SDET interview rounds at companies like Amazon and Apple. The Apple and Amazon SDET Interview Questions will help you gauge the kind of expectations from you as a potential SDET.

An SDET job is one of the most in-demand jobs within the tech industry as organizations are increasingly looking to hire SDET unicorns who serve as all-rounders by embodying the skills of a developer as well as a tester

We at Syntax Technologies provide you with an outstanding opportunity to acquire expertise in the field. Read more about our QA Automation Training course here:

sdet interview questions preparation

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