Backend Testing – tools, procedures, interview questions, checklist

The backend is a key part of any software product. In this article, we’ll look at what is backend testing, how it’s tested, what a backend developer does, and what tools are used to verify its reliability and performance.

What is Backend testing (BE)?

The backend is the technological part of a software system that is not directly visible to the user. It includes the server, database and application logic. The server provides communication between the frontend and the database. The database stores the data, the application logic processes requests and performs operations on the data.

Backend testing

Backend testing is an important aspect of software development for several reasons:

  1. Reliability and Functionality: backend testing ensures that the server side of the application works correctly and as expected under a variety of conditions.
  2. Performance: helps identify bottlenecks and optimize code for better performance and speed.
  3. Security: backend testing involves testing the security of the application to avoid potential security risks.
  4. Scalability: it helps to see how well the application can handle the load of users and the growing volume of data.

Backend applications can be tested at different test levels:

  1. Unit tests:
  • They test individual backend components such as functions, classes or modules.
  • They verify that the different parts of the code are working correctly are consistent with the requirements.
  1. Integration tests:
  • They test the cooperation between different backend components.
  • They verify that communication between parts of the system is smooth.
  1. Functional tests:
  • It simulates real application use.
  • It tests whether the backend responds correctly to specific user actions and generates the expected outputs.
  1. Performance tests:
  • These tests focus on backend performance and scalability.
  • They verify how the system handles load and response with different numbers of users.
  1. Safety tests:
  • They verify application security and data security against unauthorized access.

Backend Web Development

Backend web development deals with the development of the server side of web applications. It uses various technologies and frameworks such as Node.js, Python, Ruby, PHP and many more.

Job Position – Backend Developer

A backend developer is a professional responsible for the development, implementation and maintenance of the server side of the software. His tasks include:

  • API design and implementation: creates and manages interfaces for communication between the frontend and backend.
  • Database management: Designs and maintains the database, provides optimizations and data backups.
  • Security: Responsible for securing the application and data from unauthorized access.

Backend testing interview questions

Here are some frequently asked questions and answers about backend testing interviews.

  1. What is backend testing?

Backend testing is the process of testing the functionality of the backend or server-side components of an application. This includes database, application logic and API testing. Backend testing is important to ensure that the application can handle the expected load and traffic.

  1. Can you explain what a database schema is in the context of backend testing?

A database schema is the structure of a database that includes the tables and fields that are inside of it. In the context of backend testing, the database schema can be used to verify that the data being fed into the database are valid and match the expected structure.

  1. How do you envision test cases for backend testing?

There are several different ways to approach backend testing. One way is to think about the different types of data that will be going through your system and how you want to test that data. Another way is to think about the different types of features your system will need to support and how you can test those features.

  1. What are some common types of backend tests?

There are many different types of backend tests, but some of the most common include unit tests, integration tests, and system tests. Unit tests focus on testing the functionality of individual components, while integration tests check how these components work together. System tests, on the other hand, test the system as a whole to see if it meets the requirements.

  1. What tools or frameworks do you use for backend testing?

There are several different options of tools and frameworks for backend testing. Popular options include JUnit, TestNG and Spock.

  1. Why do we need to perform backend testing?

Backend testing is important to ensure that the server side of the application is functioning properly. This includes testing the database, API and all other server-side components. Backend testing can help uncover issues such as performance bottlenecks, security vulnerabilities, and bugs that could affect application functionality.

  1. What skills would you need to become an expert in backend testing?

There are a few key skills that are required for backend testing. First, it is important to have a good understanding of the different backend technologies used, such as databases, servers, and networks. In addition, you need to have a good understanding of the various testing tools and frameworks that are available. Finally, it is important to have good problem-solving skills so you can identify and resolve issues quickly.

  1. What should our team focus on when performing backend testing?

There are a few key areas that the team should focus on when performing backend testing:

– ensuring that the data entered into the system are valid and accurate,

– Testing various API calls to ensure they work properly,

– checking the database to ensure that data is stored and retrieved correctly,

– testing the security of the system to ensure that sensitive data is protected.

  1. Which programming languages are suitable for writing backend tests?

Any programming language can be used to write backend tests, but some languages are more suitable to the task than others. For example, Python is a popular language for writing backend tests because it is easy to read and has a large number of libraries that can be used for testing purposes.

  1. Is it possible to write backend tests without programming knowledge? If so, how?

Yes, it is possible to write backend tests without coding knowledge. This can be done using a tool like SoapUI, which allows you to create and run tests without having to write any code.

  1. What does a typical backend test suite look like?

A set of backend tests typically includes a set of unit tests that test the functionality of the backend code, as well as a set of integration tests that test how the backend code interacts with the rest of the system.

Prepare yourself for the interview and study the most frequently asked questions about backend testing.
Prepare yourself for the interview and study the most frequently asked questions about backend testing.
  1. What is SQL injection?

SQL injection is a type of cyber attack in which a malicious user attempts to insert SQL code into the input of a web form in order to execute a query on a backend database. This can be used to steal data or corrupt the database.

  1. What are the ways to prevent SQL injection attacks?

There are several ways to prevent SQL injection attacks:

– Use parameterized queries instead of concatenating strings to build SQL queries. This will help to ensure that only the intended data is entered into the database.

– Perform input validation for all data entered by the user. This will help to ensure that only valid data is sent to the database.

– Use the white list of allowed characters instead of the black list. This will help to ensure that only the intended data is entered into the database.

  1. How can you tell if there are duplicate rows in a table?

There are several ways to see if there are duplicate rows in the table. One way is to use the COUNT() function. This function returns the number of occurrences of rows in the table. If there are duplicate rows, the COUNT() function returns a number greater than 1. Another way to detect duplicate rows is to use the GROUP BY clause. This clause groups rows that have the same values. If there are duplicate rows, they will be grouped together.

  1. What is the difference between NULL and 0 in SQL?

NULL is a value that indicates that no data is available, while 0 is a value that indicates the absence of a value. In SQL, NULL is used to indicate that the value is unknown, while 0 is used to indicate that the value is known.

  1. Can you give some examples of real-world scenarios where backend testing is used?

Backend testing is used to ensure that the server-side components of the application are functioning properly. This can include database testing, API testing, and application logic testing.

  1. What are the different phases involved in database testing?

There are four main phases in database testing: unit testing, integration testing, system testing and user acceptance testing. During unit testing, individual database components are tested to ensure that they are functioning properly. During integration testing it verifies that different backend components work together as expected. In system testing, the entire database system is tested to ensure that it meets all the requirements. Finally, in user acceptance testing, real users test the system to make sure it is usable and meets their needs.

  1. Can you explain what a database transaction is?

A database transaction is a set of SQL statements that are executed together as a single unit. Transactions are used to ensure the consistency and correctness of the data in the database. For example, if you are transferring money from one bank account to another, you would want to use a transaction to either update both accounts correctly or not update either account. This way you can be sure that the data in the database is correct and consistent.

  1. What is the importance of using databases with ACID properties?

Databases with ACID properties are important for backend testing because they help ensure the consistency and accuracy of stored data. If the database does not have ACID properties, data is more likely to be lost or corrupted.

Backend testing tools

There are many backend testing frameworks, some of which are:

  • Postman: For API testing via HTTP requests.
  • RestAssured: RestAssured is a Java-based library for testing RESTful APIs. It provides an intuitive syntax for making API calls and verifying responses, making it a popular choice for test automation.
  • JUnit, NUnit, PyTest: For writing and running unit tests.
  • Selenium: Although it is more commonly used for frontend testing, it can also be used for backend integration testing.
  • JMeter: It is used for backend performance testing.
  • LoadRunner: Helps with testing application performance, scalability and stability.
  • Gatling: Gatling is another powerful tool for testing the performance of web applications, including backend services. It is known for its effectiveness in simulating a high number of virtual users to stress test backend systems.
  • SoapUI: SoapUI is used to test SOAP and REST APIs. It provides a user-friendly interface for designing and executing tests of backend services.
  • K6: K6 is an open-source load testing tool used to test the performance of APIs, backend services and web applications.

Backend testing vs API testing

  • Backend testing is a broader concept that includes testing of the entire backend, including APIs, databases, server logic, and more.
  • API testing is a specific type of backend testing that focuses solely on testing APIs.
  • Backend testing covers a wide range of components and aspects including databases, server logic, performance and security.
  • API testing deals with API endpoints, request and response validation, authentication, authorization, and error handling.
  • Tools used for backend testing include various testing frameworks, performance testing tools, security testing tools, etc.
  • API testing uses specialized tools designed specifically for API testing, such as Postman and SoapUI.

Backend testing checklist

  1. Unit Testing :
  • Verify that the individual components (functions, methods, classes) of the backend code work as expected.
  • Test boundary cases, invalid inputs for each unit.
  • Make sure that unit tests are independent, isolated and do not depend on external factors.
  1. Integration Testing:
  • Test the integration of different backend components (e.g., APIs, services) to see if they work together seamlessly.
  • Make sure that the data flow and interaction between different components is correct and working properly.
  • Look for possible data inconsistencies when integrating components.
  1. API Endpoint Testing:
  • Verify that each API endpoint is working properly and returns the expected status code.
  • Test different HTTP methods (GET, POST, PUT, DELETE) for each API endpoint.
  • Verify request and response formats (e.g. JSON, XML) conform to API specifications.
  1. Data Validation and Database Testing:
  • Ensure that data is correctly stored, queried and updated in the database.
  • Verify that data integrity restrictions (e.g. unique keys, foreign keys) are properly applied.
  • Test database connections, transactions and rollback changes.
  1. Performance Testing:
  • Perform load testing to ensure that the backend can handle the expected user load without performance degradation.
  • Test backend response time and latency under normal and peak load conditions.
  • Check how the system behaves under load and whether it recovers correctly.
  1. Security Testing:
  • Conduct penetration testing to identify vulnerabilities and potential security risks in the backend system.
  • Make sure sensitive data is encrypted and handled securely.
  • Verify that access control and user authentication mechanisms are effective and secure.
  1. Error Handling:
  • Test error scenarios to ensure that appropriate error codes and messages are returned.
  • Verify that error messages do not reveal sensitive information.
  • Check the error logging mechanisms to make debugging and troubleshooting easier.
  1. Caching and Performance Optimization:
  • Test memory caching mechanisms to ensure they improve performance as expected.
  • Verify that memory caching strategies do not compromise data consistency.
  • Check that performance optimizations are effectively implemented and are improving system response time.
  1. Concurrency and Multithreading Testing:
  • Test how the backend handles concurrent requests and multiple users accessing the system at the same time.
  • Make sure that the backend remains stable and reactive with the current approach.
  1. Compatibility Testing:
  • Test the backend on different operating systems, browsers and devices to ensure compatibility.
  • Make sure the backend works properly with different versions of third-party components and libraries.
  1. API Documentation:
  • Verify that the API documentation is accurate, up-to-date, and comprehensive.
  • Make sure the API documentation includes details about each endpoint, request parameters, response format, and error handling.
  1. Continuous Integration/Deployment:
  • Integrate backend testing into your CI/CD process to ensure automated testing with each deployment of a new application version.
  • Verify that automated backend tests are run as part of the continuous integration process and fail if the tests fail.
  1. Backup and Recovery Testing:
  • Test backup and recovery procedures to ensure that data can be recovered in the event of a failure or data loss.
  1. Logging and Monitoring:
  • Verify that events and errors are logged correctly for monitoring and debugging.
  • Ensure that the logs provide sufficient information to diagnose and troubleshoot problems.
  1. Cross-Functionality Testing:
  • Verify that the backend works properly with other systems, third-party integrations, or external services with which it interacts.
  1. Scalability Testing:
  • Test the ability of the backend to scale horizontally and vertically to handle increased systems loads and traffic.
  1. Disaster Recovery Testing:
  • Verify the ability of the system to recover from catastrophic failures with minimal downtime and data loss.
  1. Legal and Compliance Testing:
  • Make sure the backend meets legal requirements and industry standards (e.g. GDPR, HIPAA).
  1. User Acceptance Testing (UAT) Support:
  • Work with the Quality Assurance (QA) team to provide the necessary backend support during user acceptance testing.

Backend testing is a key step in the software application development process. Properly performed backend tests ensure that server components are reliable, powerful and secure. In this article, we have reviewed various aspects of backend testing and created an extensive checklist for the process.

It is important to remember that backend testing is not an isolated process. Collaboration between development and testing teams, integrating testing into the CI/CD process, and continuously improving testing procedures are key to achieving a successful outcome.

If you’re an IT tester and you speak German, check out our job offers. You might be interested in a job offer. We have great employee benefits and a friendly company atmosphere.

About the author

Michaela Kojnoková

Agile Test Engineer

Po štúdiu informatiky na ŽU a TUKE som sa najviac ponorila do oblasti automatizácie testovania. Okrem toho sa venujem tvorbe webov, databázam, dátovej analytike, umelej inteligencii a strojovému učeniu. Mám rada cestovanie, šport a najviac si užívam čas strávený v prírode s mojimi blízkymi. LinkedIn

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