Integration Testing Big Bang, Top Down, Bottom Up & Hybrid Integration

In both approaches, top-down and bottom-up integration testing, the top-down generates more redundant results and leads to additional efforts in the form of overheads. Equally, the bottom-up approach is challenging but more efficient than the top-down approach. Integration testing is usually done simultaneously with development.

top-down testing

High-level modules are tested first and then low-level modules and finally integrating the low-level modules to a high level to ensure the system is working as intended. It is sub divided into Big Bang Approach, Top Down Approach, Bottom Up Approach and Sandwich or Hybrid Integration Approach (Combination of Top Down and Bottom Up). This process is carried out by using dummy programs called Stubs and Drivers.

Main target layer in the middle, another layer above the target layer, and the last layer below the target layer. The top-down approach is used on the layer from the top to the middle layer. The bottom-up approach is used on the layer from the bottom to middle. Incremental Testing is performed by connecting two or more modules together that are logically related.

What Is Unit Testing? Everything That You Need To Know About Unit Testing

Verifying if the individual units are communicating with each other properly and working as intended post-integration is essential. Integration Testing is a level of software testing where individual units are combined and tested to verify if they are working as they intend to when integrated. Integration testing is an approach where different components or modules of a software application are tested as a combined entity.

Top Down Integration Testing

The main objective of integration testing is to ensure that the entire software system works flawlessly when it is put together. During the unit testing phase, if any critical aspects are overlooked, they are highlighted and, in turn, can be corrected before the final launch. Regarding automated testing, Selenium is the most widely-used framework for integration testing. If you start with integration testing, don’t waste time setting up expensive in-house test infrastructure.

What is Integration Testing? A Simple Guide on How to Perform Integration Testing

Make sure you have properly outlined all components to ensure the successful completion of tests. Today, we’ll look at what integration testing is, the various types of integration testing, and provide you with a how-to guide to explain the process. At different companies, different roles may be responsible for writing and running the integration tests. It all depends on each company’s hiring policy, as well as the engagement model for software delivery and the developer-to-tester ratio in the team. Thus, both the software developer and the systems integration or test engineer can be in charge.

Top Down Integration Testing

Its simple onboarding process makes it easy to perform mobile app and web testing. LambdaTest supports automated testing tools like Selenium, Cypress, Playwright, Puppeteer, Appium, Espresso, and XCUITest, among others. In most cases, it happens in parallel with the development process, which is the most efficient approach. In the top-down integration testing, if breadth-first approach is adopted, then we will integrate module M1 first, then M2, M6.

It works on the core principle of testing the combined smaller units as a single big piece. For this, we need only two things – know the module dependencies and the steps to move ahead. In the top down integration testing approach, we first test the data records, then the data records integrated with Profile Page, and then all three. Top down integration testing is a type of incremental testing where we move from top to down and keep integrating modules as we move ahead.

The only thing we need to remember here is to draw the diagram with logical modules only, i.e., the modules that will get connected in the application. This technique follows the control flow or architectural structure to test it from top to bottom. Unit testing is performed on the top module alone, followed by integration of the lower modules. In this way, all the modules are integrated and tested simultaneously. Bottom-Up integration testing, on the other hand, starts with testing the

lower-level components first, ensuring they function correctly in isolation.

Top Down Integration Testing

It is a combination of Top-down and Bottom-up approaches therefore it is called Hybrid Integration Testing. The top-down approach starts by testing the top-most modules and gradually moving down to the lowest set of modules one-by-one. Testing takes place from top to down following the control flow of the software system.

  • Hope the things that you have learned here today will help you as you head out on your software testing journey.
  • Within that process, integration testing stands out as the most important.
  • As there is a possibility that the lower level modules might not have been developed while top modules are tested, we use stubs instead of those not ready modules.
  • It is an important part of the testing cycle that makes it easy finding defects when two or more units are integrated.
  • If you are new to software testing, be sure to also read the Beginners’ Guide for Software Testing.

Integration testing is a primary phase of the software testing process when testing is done at the development stage. Both have their advantages, but top down performs better and is the most common approach used in integration testing when scenarios are correct. The top-down testing technique is the most commonly used Integration Testing Type.

You can encounter multiple challenges while implementing integration testing. If all the steps are followed properly, that it ensures that the customer can complete a purchase successfully and the order is recorded correctly in the system. If you work in ecommerce, you need component integration testing to make sure all parts of the shopping work together smoothly. You need to make sure customers can log in, search for items in your inventory, add them to their carts, then securely pay for their purchases.

Top Down Integration Testing

To assess the functionality of the modules en masse, you must first test the modules separately. When it comes to the Top-down method, the main feature is that testing begins with the higher-level components of the software and gradually progresses towards the lower-level ones. This approach is especially advantageous when some system parts have priority over others.

The four levels of software testing are as shown in the image below. These terms (stub & driver) come into the picture while doing Integration Testing. While working on integration, sometimes we face a situation where some of the functionalities are still under development. So the functionalities which are under development will be replaced with some dummy programs.

This process ensures that individual software components create a cohesive, functioning system. Integration testing focuses on testing the interactions between software modules to ensure they work together as intended. This means that you won’t know if there are any interaction issues in the lower-level modules. Sometimes companies employ independent testers to do it for them.

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