System Integration Testing: How to Do & Best Practices

This blog offers an exhaustive overview of System Integration Testing, including its purpose, process, and best practices. Through this blog, you will better understand System Integration Testing and how to validate the interactions between system components and the outside world. Now let’s start with a short definition of SIT!

What is System Integration Testing?

System Integration Testing (SIT) is a crucial software testing technique to assess individual modules’ seamless interaction and functionality within a larger system. The development team conducts SIT at the end of the software development cycle to ensure optimal performance of the combined system and meet the client’s expectations.

This testing approach comprises a black box, smoke, and regression testing. By identifying any issues caused by integrating new components or changes to existing ones, SIT helps to ensure that the entire system functions efficiently.

Why System Integration Testing?

System integration testing is essential for achieving a successful and high-quality product, as it helps ensure that all the individual components of the system are working together correctly.

Who Performs System Integration Testing?

A Quality Assurance (QA) professional typically performs system integration testing. 

In some cases, the development team can also perform the tests. 

Depending on the complexity of the system and its components, additional resources may be needed to ensure a complete end-to-end test.

Example of System Integration Testing

Here’s an example scenario of system integration testing:

Let’s consider a hypothetical e-commerce platform that consists of several modules:

• User Authentication Module: Handles user login and registration.
• Product Catalog Module: Manages products available for sale.
• Shopping Cart Module: Allows users to add/remove items from their shopping cart.
• Payment Processing Module: Facilitates secure payment transactions.

During system integration testing, we want to ensure that all these modules interact correctly and fulfill the overall business requirements of the e-commerce platform.

Example Test Scenario:

Test Case: Login, Look for a product, Add Item to Shopping Cart and then buy it.

1. Preconditions:
   1. The user is logged in.
   2. Products are available in the catalog.
      
2. Test Steps:

a. Navigate to the product catalog.

b. Select a product and click the “Add to Cart” button.

c. Verify that the product is added to the shopping cart.

d. Check if the shopping cart displays the correct product details and total price.

e. complete the payment process for the product.

3. Expected Results:
   1. The selected product is successfully added to the shopping cart.
   2. The shopping cart reflects the correct product details and total price.
   3. The payment should be successful and needed emails and notifications should be sent to the buyer and the seller.
      
4. Test Data:
   1. Valid user credentials for login.
   2. Sample products available in the catalog.
      
5. Test Environment:
   1. Ensure all relevant modules (User Authentication, Product Catalog, Shopping Cart) are deployed and accessible.
   2. Mock or simulate the Payment Processing Module to avoid actual financial transactions during testing.
      
6. Test Execution:
   1. Execute the test case manually or automate it using testing frameworks.
   2. Record any deviations from expected results and report defects as necessary.
      
7. Post-conditions:

The notifications should be sent correctly to the buyer and the sender. Above example illustrates, with one test case, how system integration testing ensures that different modules – User Authentication Module, Product Catalog Module, Shopping Cart Module, Payment Processing Module – function correctly together.

Understand System Integration Testing Using a Real-world Scenario!

System Integration Testing (SIT) is a type of testing in which a complete system is tested for functionality. This involves integrating individual components tested separately to ensure they work together as expected. 

Let’s consider the development of an e-commerce website to understand SIT better.

1. Define the system and its components. The first step is to define the e-commerce website system and its components. In this case, the system consists of a web application, a database server, a payment gateway, and a product catalog.
2. Identify interfaces. The next step is to identify the interfaces between these components. For example, the web application sends and receives data from the database server, communicates with the payment gateway for transactions, and fetches product information from the catalog.
3. Create a test plan. The third step is to create a comprehensive test plan that outlines the objectives, scope, resources, schedule, and test cases for the SIT phase. This plan should define what you intend to test, including data flows, interactions, and expected outcomes.
4. Prepare test data. The fourth step is to prepare test data that simulates real-world scenarios. For example, create user accounts, sample products, and various payment scenarios. Ensure the test data covers a wide range of situations users might encounter.
5. Set up a test environment. The fifth step is to set up a dedicated test environment that mirrors the production environment as closely as possible. Install the web application, database server, payment gateway, and product catalog with the necessary configurations.
6. Define test cases. The sixth step is to create detailed test cases that cover various integration points. For example, create test cases to validate user registration, product search, adding items to the cart, and completing a payment transaction.
7. Execute test cases. The seventh step is to execute the defined test cases systematically. Start with simple scenarios and gradually move to more complex ones. Log the results, including any defects or issues you encounter.
8. Monitor and analyze results. The eighth step is to monitor and analyze the test results continuously. Pay attention to any failures, unexpected behavior, or issues that arise during the testing process. Document all issues with detailed information.
9. Debug and resolve issues. The ninth step is to work closely with developers to debug and resolve integration issues as they arise. This may involve code changes, configuration adjustments, or communication protocol fixes.
10. Re-test and regression testing. After resolving issues, re-test the system to ensure the integration problems have been successfully fixed. Also, perform regression testing to confirm that new changes have yet to introduce defects in existing functionality.
11. Final validation. The eleventh step is to validate the entire system to ensure all integration points work as expected. This validation should include end-to-end testing of common user scenarios.
12. Documentation. The twelfth step is to document all the test results, including successful integrations, resolved issues, and any workarounds implemented. This documentation is essential for future reference and for sharing information with stakeholders.
13. Sign-off. The thirteenth step is to obtain sign-off from relevant stakeholders to signify the completion of SIT.
14. Handoff to User Acceptance Testing (UAT). After successful SIT, hand off the system to User Acceptance Testing (UAT) for further validation by end-users. UAT focuses on ensuring that the system meets business requirements and user expectations.

Granularity of SIT

Granularity in System Integration Testing (SIT) refers to the level of detail and scope of testing within a software system. It represents how finely or broadly you focus your testing efforts on various components, interfaces, or interactions within the system. The choice of granularity depends on the specific testing objectives and the complexity of the tested system.

Different Levels of Granularity in SIT

There are three main levels of granularity in SIT:

• Fine-grained (Component-Level) SIT

Testing is highly detailed at this level, focusing on individual components or modules in isolation. It involves verifying the functionality of each component independently.

• Moderate-grained (Interface-Level) SIT

At this level, you test interactions between different components or modules. It focuses on verifying that components communicate and exchange data correctly through their interfaces.

• Coarse-grained (End-to-End) SIT

Coarse-grained SIT involves testing the entire system or a significant portion of it. It evaluates how all components work together to deliver a complete user experience.

Mixed Granularity SIT

In practice, you may use a combination of granularity levels. For instance, you might perform fine-grained testing for critical components, interface-level testing for interactions between less critical components, and coarse-grained testing for end-to-end scenarios.

Choosing the Right Granularity for SIT

The right granularity for SIT depends on several factors, including:

• The complexity of the system being tested
• The specific testing objectives
• The availability of resources
• The time and budget constraints

Generally, starting with a coarse-grained approach and then refining the testing as needed is a good idea. This will help you identify the most critical testing areas and allocate your resources efficiently.

Benefits of Granularity in SIT

There are several benefits to using granularity in SIT:

• It helps to identify and address integration issues early in the development process.
• It ensures that individual components and their interactions work correctly.
• It provides a holistic view of the system’s behavior.
• It helps to allocate testing resources efficiently.
• It contributes to a more robust and reliable software system.

Advantages of System Integration Testing

Let’s look at a few advantages of system integration testing now.

1. Improves reliability by detecting and fixing defects early
2. Validates system performance, scalability, and usability
3. Supports effective cooperation between development and testing teams
4. Provides a complete view of system functionality
5. Increases customer satisfaction and devotion by delivering high-quality products.

Disadvantages of System Integration Testing

SIT is an essential part of the software development process but has some drawbacks that must be considered.

1. Cost: System integration testing can be costly and laborious due to the intricacy of the systems under examination and the requirement for specialized equipment and personnel.
2. Resource Consumption: System integration tests consume many resources, including humans, time, hardware, and software. When managing several systems at once might be challenging.
3. Risk of Data Loss: Integration tests may lead to data loss if not conducted correctly or if one of the tested systems contains a fault.
4. Difficulty in Troubleshooting: In case of a problem arising during system integration testing, it can be challenging to pinpoint the exact cause due to its potential connection with multiple systems or components.

We spoke about the upsides and downsides of system integration testing. Yet, it depends on your familiarity and skill in conducting the many tests relevant to your product.

Prerequisites of System Integration Testing

Below are some recommendations for what to do before you start executing your system integration tests:

1. Have a clear understanding of the business requirements.
2. Make sure the team and stakeholders are on the same page about the expectations from the integration tests.

How to Do System Integration Testing?

System integration testing’s main objective is ensuring the system’s various elements work together and deliver accurate results. The team should take the following steps to execute system integration testing:

Step 1 – Plan the System Integration Test: Planning the system integration test helps identify the objectives of the test, the components of the system that need to be tested, the types of tests to be conducted, and the expected results.

Step 2 – Identify the Test Environment: The second step involves identifying the test environment. It is essential to ensure that the test environment is similar to the production environment to ensure that the tests represent the actual system.

Step 3 – Execute the System Integration Test: This step involves connecting all the components of the system and running tests to ensure that the system is functioning as expected.

Step 4 – Analyze the Test Results: The fourth step involves analyzing the test results. This involves comparing the results of the integration test to the expected results.

Step 5 – Document the Test Results: We all know documentation is essential in all the steps. This step involves creating a report outlining the test results of identified issues and suggestions for further testing or changes.

Step 6 – Make Required Changes: This step involves fixing the reported bugs and implementing the reported suggestion to ensure the system functions as expected.

Step 7 – Retest the System: The seventh step, retesting the system, is essential to ensure that the changes have been made correctly and that the system functions as expected.

System Integration Testing Techniques

Here are the four methods you may use to do system integration testing:

• Top-Down Testing Method: This technique starts with the highest-level module and works through the lower-level modules. It requires the integration of modules in a top-down fashion so that higher levels of modules are tested first.
• Bottom-Up Testing Method: This technique starts with the lowest-level modules and works through higher-level modules. It requires the integration of modules in a bottom-up fashion so that the lower-level of modules are tested first.
• Sandwich/Mixed Testing Method: Sandwich integration testing is a hybrid integration testing method that combines top-down and bottom-up integration testing methods. In sandwich integration, sub-modules are tested in addition to the top-level modules, while the top-level modules are integrated with the sub-modules for testing.
• Big Bang Testing Method: This technique involves testing all the modules together. The modules are integrated and tested simultaneously.

Read about the Differences Between Top-Down and Bottom-Up Integration Testing

System Testing Vs. System Integration Testing

Look at the below table for the differences between System and System Integration Testing.

System Testing	System Integration Testing
It is performed after unit and integration testing.	It is performed after unit testing and is a subset of integration testing.
System testing tests how the whole system behaves.	SIT tests the integration of all components of a system.
System-level errors are identified using system testing.	Interface compatibility issues are identified using SIT.
It tests how the system reacts to external interfaces.	It tests data sharing between different components of a system.
It focuses on end-to-end system functionalities.	It focuses on interactions between components of a system.

When to Automate your System Integration Testing?

System Integration testing should be automated when the System integration tests are complex and require a lot of data setup and verification. Because we know Automation can

• Save time,
• Reduce errors, and
• Make it easier to run tests regularly.

Automating integration testing also makes detecting bugs and regressions in the system easier.

Top 3 Tools to Automate System Integration Testing

Selecting suitable integration testing tools is necessary to implement the integration testing process effectively. The following three tools are among the most popular for Integration Testing:

Testsigma

Testsigma offers automation capabilities to help you quickly set up automated integration tests. Some of its top features are:

1. Testsigma is a no-code test automation tool that supports test case creation in simple English; test cases are as easy to create as writing sentences in English. In addition, it also lets you record your test steps.
2. It lets you automate web, mobile, APIs, and desktop tests from the same place. Thus your integration tests covering all these platforms can be executed easily.
3. It provides a wide suite of features that allow users to create test cases, set up test environments, run tests, analyzes results, and generate reports.
4. Testsigma also allows users to integrate with bug-tracking systems, so any issues discovered during testing can be tracked and addressed quickly.
5. The platform is designed to make it easier for teams to collaborate on projects.
6. By using automated tools like Testsigma, businesses can start saving time and money from day.

TOSCA

TOSCA stands for “Topology and Orchestration Specification for Cloud Applications” and was developed by Tricentis, an Austrian software company. This software testing tool assists in creating automated tests for various applications. Some of its top features that can improve integration testing are:

1. Supports automation of tests for complex systems.
2. Tosca is compatible with various applications, including Salesforce, SAP, Web, PowerBuilder, DotNet, Mainframe, and Mobile Devices.
3. A model-based approach to simplify test case creation and management
4. A collaborative framework for testers to communicate seamlessly
5. Generates detailed reports and metrics

Ranorex

If you’re in the market for an integration testing tool, then Ranorex is worth considering.

Some of its top features that can help improve your integration testing efforts are:

1. Its cross-browser testing capabilities
2. Support for multiple platforms, including Windows, iOS, and Android.
3. Intuitive interface with drag-and-drop functionality.
4. Support for testing complex scenarios involving third-party APIs and databases.
5. Generates detailed reports of each test run for easy identification of issues.

Best Practices of SIT

Integration testing should be conducted following certain best practices to ensure satisfactory results. These include:

For manual testing

Before you start the test execution:

• Understand the architecture of the system and its components.
• Plan the test strategy and prepare the test cases.
• Design a test environment that accurately reflects the production environment.
• Create test cases to test the integration of each system component with the others.
• Create test data to cover various scenarios.

Once the preparation is done:

• Execute integration tests as per the test cases
• Log defects.
• Monitor the performance of the integrated system.

Before wrapping up, make sure you:

• Re-test after defect resolution.
• Retest for regression after change requests.
• Document the test results.
• Record the performance metrics.

For automated testing

• Choose to automate test cases that focus on integration points between different systems.
• Make sure that all automated test cases cover all interfaces.
• Give priority to test cases that simulate real-world scenarios.
• Also, keep track of the performance parameters during the tests.
• Automate end-to-end tests to ensure that data is being processed correctly.
• Execute the automated test cases frequently to ensure no bugs emerge after new fixes.

Read all about Integration Testing

Wrapping up

In conclusion, System Integration Testing is a necessary stage in software development. It ensures that all the different components of the system work together seamlessly and efficiently. By carefully studying all tests and documents, the system can be launched confidently, knowing it will work as intended. Ultimately, system integration testing helps ensure the success of software projects and end-users satisfaction.

Automating the integration test cases is recommended when they are too complex to be executed manually or repeatedly. Testsigma is a tool that can help automate system integration tests easily as it supports the automation of web, mobile, desktop, and API tests from one place. Also, it’s a no-code test automation tool that lets you start your test automation within minutes. Thus, it is well-suited for agile methodologies for software development.

Frequently Asked Questions

What are the 5 system integration methods?

1. Big Bang Integration
2. Incremental Integration
3. Top-Down Integration
4. Bottom-Up Integration
5. Sandwich Integration

What is system integration testing in Agile?

Agile is when software development happens in multiple iterations, and at the end of every iteration, a usable product is developed. Thus, for agile – the system integration testing will have to be executed at the end of every such iteration.

What is System Integration Testing vs. UAT?

System Integration Testing (SIT) is a type of software testing that verifies that all of the components of a system work together as one unit. It differs from User Acceptance Testing (UAT) in that SIT focuses on the system as a whole, ensuring that all of the different parts of the system are working together correctly. In contrast, UAT focuses on the user experience and how the system behaves when used.