What is System Testing? [Definition, Process, Types]

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What is System Testing? [Definition, Process, Types]

Sameeksha Medewar
Last updated on July 21, 2024

    Companies and organizations carry out numerous types of software testing on their products before releasing them to the market. In general, software testing assures that a certain software product is in compliance with the predefined specifications, meets the quality standards, and has no errors.

    Each type of software testing has a specific goal to accomplish that ultimately improves the quality of the final product. Among all, system testing is one of the most popular types of software testing. In the hierarchy of the software testing levels, this type of testing comes after unit and integration testing.

    Unit testing evaluates each unit or module of the software product individually to verify its correctness. On the other hand, integration testing logically combines the tested units or modules and tests them as a group. It identifies inconsistencies between the two software modules or units when integrated.

    System testing takes the input as integrated components from integration testing and tests them as a whole system to make sure that the system meets the specified requirements.

    Through this article, we will help you expand your knowledge of system testing, its types, advantages, and disadvantages.

    So, let us begin our discussion!

    What is System Testing?

    System testing is a type of software testing that takes integrated components as input and tests the system as a whole in accordance with its specified requirements. The primary goal of this type of testing is to identify errors within the integrated components as well as within the system as a whole.

    Generally, any computer system is a combination of software and hardware. A piece of software is just an element of the computer system. Initially, the software is developed in units and then integrated with other software and hardware to create a full-fledged computer system.

    In other words, a computer system is a group of software applications that perform specific tasks. However, only software applications are not sufficient for a computer system to function. Instead, they must be interfaced with compatible hardware.

    Therefore, this type of testing involves a series of multiple tests to determine the working of a full-fledged computer system against the functional requirements, non-functional requirements, or both.


    The following are the characteristics of system testing:

    • A team of dedicated testers performs this type of software testing after integration testing and before user-acceptance testing.
    • This type of software testing is the first testing technique that tests the software product as a whole in the software development life cycle (SDLC).
    • It verifies whether the complete system functions as expected and meets the pre-defined functional specifications.
    • It also validates the complete system for its architecture and business requirements.
    • This type of testing comes under black-box testing.
    • It may include both functional and non-functional testing since it tests the complete system against functional requirements, non-functional requirements, or both.

    What Does System Testing Verify?

    This type of software testing involves:

    • Verifying a completely integrated software product, along with its external peripherals, to ensure that all the components work well with one another and with the system as a whole. It is end-to-end testing.
    • Providing various inputs to the system and checking the actual outputs with the desired ones.
    • Testing the system from the users’ perspective for its behavior.

    Moreover, this type of software testing primarily focuses on the following parameters while testing the software products:

    • External interfaces
    • Security
    • Recovery
    • Performance
    • Installability
    • Usability
    • Load or stress
    • Documentation
    • The smooth interaction of users and operators with the system
    • Complex functionalities

    In a nutshell, we can say that system testing tests the behavior of the software product from the end users’ perspective, along with the assurance that it meets the customers’ expectations. It does not require knowledge of the system’s internal structure and implementation details. Therefore, it is a type of black-box testing.


    To have a better understanding of system testing, let us take an example of car manufacturing. The car manufacturers do not produce cars as a whole. Initially, they manufacture each component of the car independently, such as seats, breaks, mirrors, steering, car frames, etc.

    Once they develop all the essential components, they test them independently to check whether they function as intended, which we can refer to as unit testing in the context of software testing.

    Later, they assemble the tested components or parts of the car and check whether the assembly of components has created any inconsistency or not, and we refer to this as integration testing.

    After assembling all the components together, the car is not yet ready. Instead, the manufacturers check the car as a whole against the predefined requirements, such as whether it runs smoothly, the color of the car is as expected, how many miles the car can cover in an hour, how it runs on a sloppy, straight, and bumpy roads, and many other aspects. This is referred to as system testing.

    Why System Testing?

    Here are a few significant reasons for performing system testing:

    • It ensures that the software product meets the quality standards.
    • This type of software testing assures that the software product complies with functional, non-functional, and technical requirements that the clients or end-users specify at the onset of development.
    • A team of professional testers carries out this type of testing in an environment similar to the production environment. Therefore, developers and stakeholders can identify or predict the end users’ reactions to the product.
    • It helps in reducing the issues and bugs in the product even after production.
    • Since it tests end-to-end functions of the software product, it guarantees the 100% performance of that product.

    When to Perform System Testing?

    The following are certain scenarios where testers perform system testing either manually or using tools:

    • After performing unit and integration testing.
    • Before carrying out user-acceptance testing.
    • On the integration of all software modules.
    • When the entire software product is developed as the Software Requirements Specification (SRS).
    • When the test environment is ready.

    Entry-Exit Criteria for System Testing

    Entry Criteria

    The entry criteria provide the prerequisite items that the testing team has to complete before starting to test. The following are the entry criteria for system testing:

    • The software product should have passed the exit criteria of integration testing.
    • The test plan should be approved and signed off.
    • The testing team should keep the test cases ready for execution.
    • They should execute all the test scripts or test cases.
    • All the non-functional requirements should be available, and the testing team should have created the test cases for the same.
    • The testing environment should be ready.

    Exit Criteria

    The exit criteria are the prerequisite items that the testing team has to finish before the testing process ends. Here are the exit criteria for system testing:

    • The testing team should execute all the test cases.
    • There should be no priority, security, or critical bug present in the system in the open state.
    • The testing team should submit the exit report.

    System Testing Process

    The process of system testing varies from organization to organization and project to project. Here are some common steps involved in system testing:

    • Create a Test Plan: The first step in any testing process is to create a detailed test plan. In this step, the test manager is responsible for defining the scope and goals of testing, selecting the test strategy, deciding between manual or automated testing, defining the entry and exit criteria, and assigning roles and responsibilities to the testing team.
    • Test Case Creation: The actual process of testing starts from this step. Here, the testing team creates multiple test cases based on the use cases and functional, non-functional, and technical requirements.
    • Select Test Data: After the team creates test cases, they concentrate on collecting the required test data. Generally, test data is a set of inputs to be fed to the system to produce the actual results.
    • Test Case Execution: Once they collect test data, they start executing test cases. Also, the testing team records the result of the execution of each test case.
    • Bug Reporting and Fixing: If the team encounters errors or bugs while executing test cases, they record all of them in a document and report it to the development team. The development team works on fixing errors and bugs and sends the modified code for retesting.
    • Repeat the Test Cycle: The above cycle repeats until the testing team finds no bugs or errors in the software product.

    Types of System Testing

    There are around 50 different types of system testing. The following is the list of some popular types of system testing that most software development companies use:

    • Usability Testing: This type of testing ensures that the software product is easy to use and meets the specified requirements.
    • Load Testing: This type of testing ensures that the software product functions as intended without any glitches under real-time loads.
    • Regression Testing: Regression testing ensures that the changes made in any part of the source code do not result in bugs or errors. Moreover, it assures that old bugs will not appear again with the addition of new modules to the software product.
    • Functional Testing: The testing team performs functional testing to check if there is any missing functionality in the software product. In addition, the team prepares the list of additional functionalities to be added to the product to improve its quality, while performing functional testing.
    • Recovery Testing: Recovery testing assures that the software product is capable of recovering itself from all possible system failures and crashes. Moreover, it confirms the reliability, trustworthiness, and accountability of the software system.
    • Security Testing: This type of testing evaluates the security features of the software product to ensure the protection, authenticity, confidentiality, and integrity of data.
    • Migration Testing: Migration testing is performed to ensure that the software product can migrate to a new infrastructure from the older one without any errors or issues.
    • Hardware/Software Testing: Often referred to as HW/SW testing, this type of testing ensures that the hardware configuration is compatible with the software product to run it without any errors. In simple terms, it makes sure that the interactions between software and hardware do not result in any issues.


    Here reached the end of our discussion on system testing. It is a type of software testing that tests a fully-integrated software system based on the functional and non-functional requirements to assess and monitor its behavior. A team of skilled professionals carries out system testing on the software product after integration testing and before user-acceptance testing.

    In addition, this type of testing ensures that the system as a whole works as expected and meets the end users’ expectations. It ensures the delivery of high-quality software products.

    We hope you found interesting information about system testing in this article. If you have any doubts regarding this article, you can post them in the comments section below.

    Frequently Asked Questions

    1. What are the four levels or stages of software testing?

    The four levels or stages of software testing are as follows:

    • Unit testing
    • Integration testing
    • System testing
    • User-Acceptance testing

    2. What is the end goal of system testing?

    The end goal of system testing is to ensure that the system behaves as expected in a particular environment. Also, it mitigates the risks associated with the behavior of the software product.

    3. When to perform system testing?

    Since it is the third level of software testing, the testing teams perform it after integration testing and before user-acceptance testing.

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