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Everything You Need To Know About Integration Testing

By TechDogs Editorial Team

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Overview

If you’re a sports fan you probably have a favorite player. If not, you surely must be hearing or reading a lot about certain players, whether online, in the news or amongst peers. Those few players who are always the center of attention and are considered amongst the top ones? (We’re not taking names!). Those few are dubbed GOATs (Greatest Of All Time). Sure, they have awesome stats, style and exude championship traits. Any team would want them, right? That’s why there are always rumors or extensive coverage about them moving to another team.

However, there’s no assurance that they would perform the same with another team. Realistically, there’s just one way to determine that. See if they link up well with the rest of the team. If they do, awesome; that was the plan! However, if they don’t, then adjustments might have to be made to how they contribute.

The equivalent of this method of testing software is known as Integration Testing. Integration Testing aims to find whether individual units perform as they’re meant to when working with other units. Read on to find out how it's done and why it’s an important process!

When Nick Fury was putting the Avengers together, he had one major worry. Would they be able to work together? He observed them individually on the job. However, would their immense personalities and varying characteristics match up well? He had brilliant individual units but as a team, they could have adverse effects. Sure enough, they didn’t play well together in the beginning but with the right push, they were able to work together.

Similarly, software applications consist of multiple units, modules or components. Most often these individual units are coded by different programmers with varying styles. While the units may carry out their functions correctly individually, they may misbehave when integrated with other units. The purpose of Integration Testing is to figure out:

If individual units or modules link and communicate with each other properly.
If there is no loss of data between exchanges.
If the modules retain their intended functions when integrated.

Tests are carried out after individual modules are built and after the system is built. However, modern software applications are quite complex with multiple sub-systems and testing is required at multiple stages. In the article, we’ll cover why Integration Testing is crucial.

What Is Integration Testing?

Software Applications are made up of various modules, units or components. The application could be a small, simple one with few modules or a big, complicated one with many. Either way, testing is vital and should go through the four main stages regardless of its size:

Unit Testing

Individual modules are tested when they’re completed. Using the team sports metaphor, this would be the equivalent of testing individual players to check their stamina, skills, endurance etc.
Integration Testing or Integration and Testing (I&T)

This is carried out to determine if each module works as it was meant to when combined with other modules, whether directly connected or not. The overall purpose of this is to determine if the modules interact well and are technically sound. The equivalent is whether players perform at their required level when mixed with other players from the squad.
System Testing

When all the modules of the project are in place, a test is conducted to determine whether the entire system functions properly and meets its requirements. This includes checking interactions with external systems and third-party tools. Just like ensuring that players and management adhere to the mission and vision of the team.
Acceptance Testing

This is done to ascertain if the software is fit for launch. Essentially, it’s a quality assurance (QA) test which could be in the form of beta testing, application testing or end-user testing. As per the above example, this would be a practice match played to test if the entire team and management are good enough to compete at the desired level.

TechDogs:-"What Is Integration Testing?"A GIF Of Tony Stark

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That’s how modules feel when they know they’re being tested with other modules during Integration Testing! The point of doing Integration Testing is to ensure that sub-systems function properly and developers can solve problems if any before they become an expensive and time-consuming reparation process.

Now, let’s see how the Avengers, we mean Integration Testing came about.

A Brief History Of Integration Testing

Obviously, Integration Testing isn’t as old as software testing, though it found its way in soon. As software applications grew and became more complex, so did the techniques and approaches toward Integration Testing (as well as for overall testing).

In 1958 Gerald M. Weinberg formed the first team for testing for Project Mercury, the first human spaceflight program of the United States.
In 1968 at the NATO Software Engineering Conference the iconic question “Is the product tested to ensure that it is the most useful for the customer in addition to matching functional specifications?” was asked.
The first mention of integration came in 1978 when William Howden spoke of a method in functional testing where the designs of programs should be considered as integrated collections of functions.
In the initial years, software developers followed the traditional waterfall methodology. This meant that they performed certain functions only when they got to that stage of the plan. Since the programs weren’t as complex as the ones we have today, this process worked fine. Even though overall development time was considerably longer.
In 2000, Integration Testing took its next leap when Martin Fowler, in his article titled Continuous Integration, described a practice where work was frequently integrated and tested. Since then, Continuous Integration (CI) and Continuous Development (CD) changed the way software developers test modules. They tested what they had available rather than waiting for complete systems or sub-systems and used dummy code for what was missing. Since it was a continuous process, modules were added when they were ready.

Cut to the present where the use of cloud technology to generate quicker and more accurate test results is prevalent. Although manual testing is still prevalent in the cloud environment, a shift to automated testing tools is on the horizon.

How Does Integration Testing Work?

Unit Testing is the testing of individual units or modules and is usually a straightforward process. Integration Testing, however, is a lot trickier. It’s the testing of multiple units, modules or components when combined. Since modules have varying hierarchal levels based on their functions, there are different methods of testing how they interact with each other. The methods of Integration Testing are as follows:

Big Bang Integration Testing

This is when all the modules of the system are tested together. This approach is suitable for smaller systems. The difference between Big Bang Integration Testing and System Testing is that the former focuses on whether the execution of the integrated modules is technically sound or not. The latter focuses on whether the integrated modules serve the required business purposes.
Incremental Integration Testing

In this approach, modules that are logically related to each other are tested together. This continues with other related modules until all are integrated and tested. In this technique, testing can commence with incomplete or missing modules (stubs and drivers).

This method is further divided based on the flow of direction of testing:

Bottom-Up

here lower-level modules are tested first leading upward to higher-level modules, integrating them as their levels are reached. This method makes it easier to find where a fault lies.
Top-Down

the testing begins at higher-level modules moving downward, essentially in the actual flow of the system. Since the more important modules are tested first, errors in bigger functions are spotted and rectified earlier sooner.
Hybrid Integration Testing

this combines the bottom-up and top-down approach, where higher-level modules are tested with lower-level modules and vice versa. It is also known as Sandwich Testing.
Stubs and Drivers

Sometimes certain modules aren’t available or are missing. So, instead of delaying the test, a dummy code is written. This is a simple code that executes the functions of the missing modules. Based on the function of the dummy code, it is termed as a ‘Stub’ or a ‘Driver’. For the most part, stubs are used in the top-down approach and drivers in the bottom-up approach.

That was interesting, right? What’s more interesting is how much we rely on Integration Testing – read on to find out!

Why Is Integration Testing Important?

Unit Testing provides answers to whether individual modules work correctly and most often, they do. However, sometimes their performance differs when integrated. Integration Testing provides a better understanding of where a problem lies. It helps prevent loss of data between module exchanges and smooth integration of third-party tools. Detecting such errors earlier in the testing process helps pinpoint where the error lies, essentially reducing reparation time and costs.

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Suffice it to say, Integration Testing is a crucial step in the development process of any software application. Without knowing if modules function correctly together or not, an application could end up with numerous bugs leading to losses in business.

So, how does this help developers and businesses?

What Are The Benefits Of Integration Testing?

Integration Testing provides an organization with a realistic view of the work done toward a project and its overall quality of it. Its primary benefits include:

Comprehensiveness

Developers get a better understanding of individual and integrated modules and a preview of the final system and its overall quality.
Efficiency

Testing multiple modules simultaneously provides a quicker, more efficient, practical and cost-effective understanding.
Bug Detection

The detection of faults in code or other issues happens in the initial testing phase and the exact problem areas can be identified.
Quicker Changes

Quite often the client requirement changes multiple times in the development process. Integration Testing provides an early glimpse into where changes need to be made to suit the updated requirement.

Although Integration Testing is the norm today, there is a lot of innovation happening in this domain.

Read on to know what to expect in the future!

The Future Of Integration Testing:

In the last few years, the Agile method of software development has brought up the concept of Continuous Integration (CI) and Continuous Deployment (CD). This coupled with QAOps (Quality Assurance Operations) allows the testing team close interaction with the development and operations teams. The benefits are quicker testing, reduced resolution time and better quality. With the introduction of automated tools Integration Testing will become even faster.

Nowadays, the norm of software development lies around cloud and quantum computing with the inclusion of AI being inevitable. Although software testing hasn’t fully embraced AI, huge strides have been made in its research. Going forward, the integration of AI in testing will provide quicker, continuous, accurate and detailed reporting. We can’t wait!

Conclusion

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If Nick Fury could test the Avengers before he needed them, he would have been a lot less desperate. Although, in the end, together they ensured the planet was safe...? What if he had the chance to test the team beforehand? He probably could have prevented the doorway for Thanos’s miscreants!
Either way, as far as software applications go, Integration Testing is a major checkpoint when building a system. Modules may function well individually but together may cause errors. Thus, to avoid a painful and pricey reparation process, developers must perform Integration Testing.

Frequently Asked Questions

What Is Integration Testing?

Integration Testing is a crucial phase in software development aimed at ensuring that various modules, units, or components of an application function correctly when integrated with each other. Just like how individual players in a team need to collaborate seamlessly, Integration Testing verifies that different modules interact properly and retain their intended functionality when combined. This testing phase is essential for detecting issues such as data loss between exchanges and ensuring the technical soundness of the integrated system.

Why Is Integration Testing Important?

Integration Testing plays a vital role in software development by providing insights into how individual modules behave when integrated, which may differ from their performance in isolation. By detecting integration issues early, such as data loss or incompatible interactions, developers can address them promptly, reducing the risk of costly reparation processes later on. Integration Testing ensures the smooth integration of third-party tools and helps developers pinpoint and resolve errors efficiently, ultimately improving the overall quality and reliability of the software.

How Does Integration Testing Work?

Integration Testing employs various methods to test the interaction between modules. One approach is Big Bang Integration Testing, where all modules are tested together, suitable for smaller systems. Incremental Integration Testing, on the other hand, tests related modules together, either bottom-up or top-down, gradually integrating and testing until all modules are integrated. Hybrid Integration Testing combines aspects of both bottom-up and top-down approaches. Additionally, stubs and drivers, which are dummy codes, are used to simulate missing modules, ensuring testing continuity.

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Tags:

Integration Testing Testing Integration Unit Testing System Testing Acceptance Testing Modules Components Software Development Programming Big Bang Top-Down Bottom-Up Incremental Hybrid Testing Stubs Drivers

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