Integration Testing Types & Techniques in Software Testing

Integration Testing Types & Techniques in Software Testing

In software development, integration testing is essential in ensuring that all system components function correctly and work together seamlessly. Critical bugs can go unnoticed without proper integration testing, leading to significant issues in production environments. This blog talks about Integration testing and Types of Integration testing.

One example of a bug found in production due to the absence of integration testing is the infamous Equifax data breach in 2017. The breach resulted from a vulnerability in the Apache Struts framework that Equifax used for their web application. This vulnerability was publicly announced, and a patch was released, but Equifax failed to apply it promptly.

This bug was not caught in testing due to the lack of comprehensive integration testing. Equifax had unit testing in place, but the absence of thorough testing between the web application and the Apache Struts framework made the vulnerability slip through the cracks. Ultimately, this bug led to the exposure of sensitive information of millions of users, causing significant financial and reputational damage to Equifax.

This incident highlights the importance of integration testing to ensure that all system components work together securely and reliably before deployment to production.

What is Integration Testing in Software Testing?

Integration testing is a software testing technique that aims to verify that when an application’s components are integrated, they all work as expected. This way, we also test the individual functionality of a component and also how the individual components interact with each other. Integration testing is done after completing unit and functional tests.

Integration testing involves testing the integration of various modules and external systems, such as the operating system, file system, and hardware. The main objective of integration testing is to detect defects that may arise due to integration issues and ensure that the system operates seamlessly.

As illustrated in the figure above, integration testing broadly follows two distinct approaches: top-down and bottom-up. There are many types of integration testing approaches; we will discuss all of them below.

Integration Testing Techniques

Blackbox Testing

In Integration testing, black box testing checks how well a system works without looking at its internal structure and design. Instead, the tester looks at how it responds to different inputs, like when you press certain buttons or type certain words.

Black box testing

This Testing ensures the system meets the needs of whoever uses it and finds any mistakes in its design. The test cases come from what the system should do, and then the tester creates scenarios based on that.


A typical example of black box testing is testing a website’s search function. The tester would not examine the code or algorithm used to generate search results. Instead, the tester would input various search queries and analyze the resulting outputs to ensure the search function works as intended.

Whitebox Testing

White Box Testing, referred to as Structural Testing or Clear Box Testing, is a form of software testing that examines the internal functioning of an application. It checks the source code, control flow, and data flow to ensure they all work together correctly. To do this test, you must know what’s happening inside the app and what code was used to make it.

White box testing

This type of Testing primarily aims to validate the application’s internal logic and ensure it works as expected. It’s usually done to ensure the app works correctly when different parts are assembled.


Take this code as an example

In software engineering, WhiteBox testing is a process that focuses on verifying all decision branches, loops, and statements present in the code. WhiteBox test cases are used to exercise the statements to achieve this objective.For example, let’s say we write code that tests the above piece of code for the below data:

  • x = 1, y = 1

  • x = -1, y = -3

We see that for data set#1, the output would be “Correct.” While for data set #2, the output would be “Incorrect.” Thus, we are able to traverse all lines of code with these data sets. Writing such tests for the purpose of interaction with the code is called white box testing.

Types of Integration Testing

The following outlines the five categories of Integration Testing types:

Big Bang Testing

So, what is Big Bang Testing? Essentially, it’s a method where all the individual components of a software system are integrated and tested at once. Instead of testing each component separately, they’re thrown into the mix to see how they work together. It’s like throwing all the ingredients into a blender and hoping for the best.

Now, you might be thinking, “Wait a minute. That sounds chaotic and risky.” And you’d be right. Big Bang Testing can be risky if not done properly. But when done correctly, it can save time and resources too.

The image below shows how to do it. Integrate all the modules from ‘Module 1’ to ‘Module 6’ simultaneously before testing.

Big bang integration testing

Here are some advantages and disadvantages of this Testing.


  1. Big Bang testing can save time and money since all tests can be done simultaneously.

  2. It provides a good overview of the system’s functionality and performance.

  3. It helps reduce the risk of missing out on any issue during Testing.

  4. Big Bang testing can be done quickly, meaning you can get your product to the market faster.

  5. It can help identify problems before the product goes live.


  1. This Testing is challenging to isolate and troubleshoot individual issues.

  2. It can be costly and time-consuming if there are problems.

  3. It can be challenging to coordinate with multiple teams and departments.

  4. Determining whether the system is ready for launch can be difficult.

  5. It can be tough to make sure all tests are done correctly.

Incremental Testing

It’s a software development approach that involves testing small pieces of code as written instead of waiting until the entire program is finished. Let me give you an example. Say you’re building a new website.

Instead of writing all the code for the entire site and testing it all at once, you might break it down into smaller pieces. So, you might start by writing the code for the homepage and then testing it to ensure it works properly. Then, you move on to the next page and do the same thing. Continue the entire test.

The below figure depicts how Integration testing can be divided into Incremental/Non-incremental Testing:

Incremental Testing


  1. Incremental Testing lets you break up the testing process into smaller chunks, so you can get results quicker and find issues faster. This means you can spot problems and figure out how to solve them more quickly.

  2. Developers can focus on adding features during the testing cycle rather than doing the same tests repeatedly.

  3. It allows users to test new features or changes to existing features in an isolated environment.

  4. We ensure the quality of building the application.


  1. This Testing requires a significant amount of planning and coordination.

  2. It may require additional resources to be available for the testing cycle.

  3. This Testing is not suitable for large projects that require extensive Testing.

  4. It can be challenging to identify and fix defects on time.

Stubs and Drivers

Alright, let’s talk about stubs and drivers. Don’t worry if you’re unfamiliar with the terminology; we’ll break it down.

First, a stub is a small piece of code that mimics the behavior of a larger component. It’s essentially a stand-in for the real thing, allowing us to test other parts of our code that depend on that component.

Drivers are used in integration testing and can be considered a “placeholder” for system parts that are not yet developed. They simulate the behavior of the missing components so that other system parts can be tested.

Stubs test individual parts of a program from the top down, while Drivers allow Testing from the bottom up.

Below is the figure for Stubs and Drivers:

stubs and drivers

Advantages of Stubs and Drivers

  1. Stubs and drivers help to test individual components in isolation from the rest of the system.

  2. They provide a way to test code before integrating it with other modules.

  3. They help to reduce the time taken for development by simulating the behavior of other components.

  4. Help to reduce the risk of bugs caused by integration issues.

  5. They can test the system before it is ready for integration.

Disadvantages of Stubs and Drivers

  1. Stubs and drivers can be challenging to create, maintain and debug.

  2. They can be time-consuming to develop and maintain.

  3. Stubs and drivers can introduce their bugs into the system.

  4. They can be challenging to update or modify if the system changes.

  5. It may not be able to simulate the behavior of other components accurately.

Bottom-up Integration Testing

Bottom-up integration testing is where we start by testing the most minor components of our software first and then work our way up to the larger ones. It’s like building a house from the bottom up – we start with the foundation, then the walls, and finally the roof.

Let me give you an example to make it easier to understand. Imagine creating a mobile app with features like login, messaging, and newsfeed. In the bottom-up integration testing approach, you would start by testing the login feature independently.

This means you would create a test environment that simulates a user trying to log in, and you would make sure the login works as intended. Once you’re confident that the login feature is working correctly, you will test the messaging feature, and it goes on.

Below is the figure of the Bottom Up Approach:

Bottom up integration testing


  1. It is cost-effective and easy to implement.

  2. It helps spot problems early on in the making process.

  3. Since tests are done at the component level, it is easier to identify and debug problems.

  4. It gives an excellent way to check if different parts are working together correctly.


  1. It takes a lot of time because you must test each part individually.

  2. This Testing can be tough to figure out where the issue comes from when different parts are combined.

  3. It requires significant resources to manage and maintain.

  4. Maintaining test cases and data for all components can be difficult.

Top-down Integration Testing

Top-down integration testing is when you test the software application from the top (i.e. the user interface) down to the lower levels (i.e. the individual functions and modules).

Let’s break it down and look at an example to understand it better.

Imagine you’re building a website. You start with the homepage and then move on to the individual pages, like the “About Us” and “Contact Us” pages.

Top-down integration testing would involve testing the homepage and ensuring it works properly before testing the individual pages. Once you’ve confirmed that the homepage and individual pages are working together correctly, you can test the components within each page, like the navigation bar and images.

Below is the figure of the Top-down Approach:

Top down integration testing


  1. This testing approach allows testers to identify the issues early in the development cycle and fix them accordingly.

  2. It helps to detect any integration issues between the modules.

  3. This method is cost-effective as it helps detect problems early in development.


  1. It can be time-consuming and costly due to the system’s complexity.

  2. Testing all the scenarios may not be possible due to the system’s complexity.

  3. Determining what’s wrong can be tricky if many parts are involved.

Sandwich Testing

Have you ever wondered how sandwich testing works in integration? Let me tell you; it’s quite an exciting concept.

First, let’s break down what sandwich testing is. Essentially, it’s a type of testing where you’re testing the middle layer of your application, hence the sandwich analogy. This middle layer is where all the different modules of your application come together and communicate with each other.

So, how do you test this middle layer? Well, that’s where integration testing comes in.

By testing your software in this way, you can ensure that all the different layers of code are working together correctly. For example, you might use sandwich testing to test how your software interacts with a database or handles user input. This type of Testing is also called Hybrid Integration Testing.

Below is the figure for Sandwich Testing:

Sandwich testing


  1. Allows for efficient Testing of two unrelated interfaces or components, saving time and resources.

  2. Can detect bugs.

  3. Easy to set up and execute.

  4. It can be used to test different layers of an application.

  5. Easier to debug since the bug is easily identifiable, and the system is unaffected by other components.


  1. Complex setup and configuration required.

  2. It can be challenging to track down bugs if the test fails.

  3. Time and resources may be wasted if the tests are poorly planned and executed.

  4. It may not be able to test all layers in an application adequately.

  5. It can be questioned to maintain and update tests.

When to automate your integration tests

You should think of automating your integration tests if one or more conditions from below are met:

1. You need to execute the same set of integration tests multiple times.

2. Your product is stable enough for test automation. This is because if you automate a product that is not stable, you end up spending more time maintaining the tests.

3. There are test cases that are easy to execute when automated and might be too much of an effort if executed manually.

4. When you calculate the cost of test automation and the efforts that it would save, you see an ROI on test automation.

Testsigma for automating your integration tests

Testsigma has multiple features that make it an ideal tool for automating your integration tests; some of them are mentioned below:

1. It lets you automate your tests for web, mobile, APIs as well as desktop from the same place and while using the same approach.

2. You have the option to customize your tests if you want to extend them.

3. With Testsigma, you don’t need to be an expert in coding – you can author and edit your tests in the same way as you would write and edit simple English sentences.

4. Not only that, Testsigma lets you integrate into device cloud labs and lets you run your tests in parallel.

5. Testsigma is also built-in with extensive support for parallel testing.

6. All of the above and more, with 24×7 support. Testsigma is also available as open-source and free.


It’s essential to do integration testing to ensure all parts of your system work together and function properly. We’ve looked at integration testing types in this blog. When planning out your integration tests, it’s essential to consider both bottom-up and top-down approaches so that all parts of your system are thoroughly tested.

Also, it’s necessary to consider what data will be used for each test and how long it will take to complete each test. By carefully planning your integration tests, you can ensure your system is tested quickly and effectively.

Frequently Asked Questions

What are the two types of incremental integration testing?

  1. Top-Down Integration Testing: This type starts with the top-level components and works through the lower-level parts, one at a time.

  2. Bottom-Up Integration Testing: This type starts with the lower-level components and works its way up through the higher-level features, one at a time.

Which Testing is integration testing?

Integration testing is the second step in checking a software project. It’s when you check each part of the project to ensure it works with all the other parts. This helps to find any problems or bugs that might be hidden so that everything works as it should.

How is Big Bang integration different from standard integration?

The main difference between Big Bang integration and standard integration is the level of risk involved. The Big Bang integration approach has a higher level of risk since all components are integrated at once, making it more challenging to identify and troubleshoot any issues that may arise. In contrast, the standard integration approach – where all integrated systems are tested methodically – is more controlled with a lower level of risk. Still, it can be more time-consuming and require additional resources to ensure each module is integrated correctly.

Test automation made easy

Start your smart continuous testing journey today with Testsigma.