Software System Integration Testing Purpose & Performance

The more complicated your program is, the more likely it is to encounter bugs that allow it to run as intended. This is why software quality assurance and running tests are some of the most important parts of software development. Various tests are performed to evaluate different types of software and their effectiveness. One such test is software integration testing. Let us look into what it is, its purpose, and how to perform it.

What is software system integration testing?

System Integration Testing, or SIT, is a software quality assurance process that tests how compatible two or more systems are. It is a crucial step in ensuring that multiple systems run in sync without facing any game-breaking issues. This testing method is especially important for large, complicated software with many moving parts. 

Objectives of software integration testing

The objectives of running SIT are

• Ensure compatibility of software systems.
• Meet user requirements
• Control data flow
• Find and squash bugs
• Test control flow

How to perform software system integration testing

There are a few methods to perform software system integration testing, with the data-driven method being one of the easiest ways. Once exchange occurs between two software systems, the behavior of the data in each layer can be observed to identify characteristics. There are three main states of datasets. They are as follows:

1. Data State within the Integration Layer

To perform SIT in this layer, basic knowledge of tools such as schema, DTD, XML, and WSDL is needed. The integration layers act as a bridge between data import and export.

Here’s what to do to run this test.

• Cross-check data properties in this layer with the BRD (Business requirement document) /FRD (Functional requirement document) /TRD (Technical requirement document)
• Cross-check web service requests using XSD and WSDL
• Run unit tests to check data mappings and requests.
• Review middleware logs

2. Data State within the Database Layer

Performing SIT within the Database layer requires the expertise of SQL and stored procedures. Here are the steps to perform this test:.

• Check if the data from the integration layer has reached and been committed to the database layer.
• Cross-check the table and column properties with the BRD/FRD/TRD.
• Cross-check the constraints and data validation rules according to specifications.
• Check procedures for any processing data.
• Review server logs.

3. Data State within the Application Layer

Here’s how you perform this test on the application layer.

• Check if all the data is visible in the UI.
• Validate data properties.
• Execute positive and negative test cases.

Software Integration Entry and Exit Criteria Testing

Entry and Exit Criteria are two essential aspects of System Integration Testing. Let us look deeper into them.

Entry Criteria

• Unit testing should be conducted for every component to ensure they are in a stable condition for integration.
• The testing environment, which includes hardware, software, databases, and networks, should be suitable for running tests.
• The datasets should be suitable for simulating real-life scenarios.
• All the test plans should be reviewed to ensure accurate results according to real-life situations.
• The interface between systems should be defined, implemented, and accessible for running tests.
• Test scripts and tools should be prepared and ready to use.

Exit Criteria

• All approved test cases should be executed.
• All defects and unintended functions should be fixed and adjusted according to requirements.
• The planned test coverage should be properly executed.
• Performance metrics such as response time and resource utilization should be up to the mark.
• The results should be examined and approved by relevant stakeholders.
• All findings, results, and modifications should be properly documented.

Software System Integration Testing Techniques

Here are a few integration testing techniques you can use for your software.

Incremental testing

For incremental testing, each module is tested separately and then tested again after incrementally connecting or disconnecting them from each other till the final product is formed. In this method, programs are divided into a hierarchical structure. This allows for identifying issues in smaller groups, making it easier to take corrective action. Interfaces are tested when the program is in full assembly. There are two ways to conduct incremental testing. They are:

Bottom-Up Integration Testing

As the name suggests, bottom-up testing starts by testing the modules at the “bottom.” These modules are assembled to create clusters that perform specific functions of the final product. A driver is created to test input and output cases.

If the tested cluster has no issues, the driver is removed, and it is connected to the next layer of the hierarchy. The process continues until the whole application is tested this way. In this method, the UI is tested last. This can be an issue as problems in the UI cannot be found earlier, and if issues arise, they can be hard to fix.

Top-Down Integration Testing

You can probably tell that top-down testing will be the opposite of bottom-up testing. Here, the UI is tested first. After which, the modules are tested. The top module layer is tested first with the lower level modules simulated with “stubs”, a sort of replacement that helps the implemented modules function.

These stubs are replaced with the intended modules after each layer is tested till the whole application is complete. They can be conducted either in a horizontal or vertical layer first manner. One issue with this testing method is that some time may be spent on creating stubs that are not essential to the final products.

Sandwich Testing

Sandwich testing can be considered to be a combination of the bottom-up and top-down approaches discussed above. Here, the system is divided into three layers, with the middle layer being considered the target layer. Testing is started from both layers, converging into the target layer.

In this method, both the top and bottom layers are tested at the same time. One disadvantage of this approach is that individual modules are not tested as much as the previous two methods.

Big Bang Integration Testing

Big Bang integration testing involves testing each and every module on its own and integrating all of them to create the final application, and testing it by itself. This testing is suitable for simple structured programs where only one of SIT is required. The main issue of this technique is that it can be difficult to find the root cause of any problem as virtually only the final product is tested for functionality issues.

Software Integration Testing Challenges

Lack of standard tools

SIT is a tool that tests the compatibility of different systems. All of them have different infrastructures, designs, and technologies. With systems that are built on fundamentally different bases, sometimes from different time periods, it can be difficult to find a standard tool that can evaluate different modules. As a result, a good amount of effort and time has to be spent to properly run SITs.

More test cycles

With more complex programs with a lot of different systems, a lot of issues will inevitably pop up that will require revisions and testing. Not to mention, one or another program may come with updates that can affect one or more integration points. So rigorous testing on different modules and integrations will need to be done, increasing the number of test cycles.

Time-consuming process

Whether you run manual or automated tests, feedback loops will be significantly delayed. Manual testing will naturally require more time to ensure every system runs properly, so feedback will come in less frequently. 

In the case of automated testing, due to a lack of standardized tools, the programs will need a lot of time and expertise to set up. So developers may spend a lot of time scripting tools instead of bugs. By the time the automation tools are ready, developers will have spent a lot of resources that could have been spent on finding and fixing bugs.

Lack of support and high maintenance

Once again, with no standardized tools, a lot of testing programs will need to be created with open-source tools. Due to how specific the combination of various modules can be, there will be a lack of community support and information, making it difficult to troubleshoot problems. So maintenance will require a lot more effort than for any standard programs.

Software System Integration Testing Best practices

SIT can be performed either manually or by automation. Here are the best practices provided for each method.

Manual testing:

• Understand the structure and hierarchy of the program
• Plan test strategies and devise practical test cases
• Collect and create test data that represent possible scenarios
• Document findings and errors systematically
• Retest program after modifications of defects
• Record performance metrics

Automated testing:

• Automate test cases that focus on integration points between each system
• Cover all interfaces
• Ensure simulation of real-world scenarios.
• Keep track of different parameters during tests
• Automate end-to-end tests to make sure that the data is processed correctly
• Run automated tests to find issues after revisions

SIT is a very important testing method that will ensure your software is running smoothly. It is pretty much a necessity when integrating different systems built on different infrastructures. We hope this guide will help you understand its necessity and how you can implement it for your software. We hope that your apps run smoothly and satisfy you and your customer’s expectations.