In a world where businesses have to tackle ever-rising consumer expectations, achieving top-notch product quality becomes compulsory! Today, most companies invest heavily in conducting software testing that involves a wide variety of testing. The software sector is expected to grow at an annual CAGR of 7.37% during 2021-26. It means that the market volume for the software sector will be equal to $800,00 million by 2026. 

Such accelerated growth in the sector enforces companies to pay extra attention to building bug-free, flawless, and errorless devices and software. As per a survey published by Statista, CIOs and senior technology experts say that almost 23% of their annual IT budget was allocated to testing and quality assurance. 

Software testing is a method to figure out whether a software product meets the desired expectations and requirements or not. It also ensures that the final product is free of errors and functions well. Some varieties of software testing allow you to test every unit of source code; hence, it helps you determine whether your application, website, or software is ready to use. 

On the other hand, a few testing solutions enable you to test different software modules. How does that benefit you? It helps your business reduce the post-launch cost of bug fixing or during the early stages of development. This article will talk about the basics of software testing and shed light on its two essential types: Unit testing and Integrated testing. Moreover, it will also discuss the critical differences between these two crucial kinds of software testing.

Software Testing: An Overview

If you ask to define software testing, the introductory part of this article has already cleared that portion. However, if the idea is still vague to you, let’s understand it through a simple example.

Suppose you want to buy a car. You will go out to the market to pick one that suits your needs and budget. Now assume that one model catches your eye and suits your pocket as well. What is the first thing that you will do to confirm your choice? Well, you will ask for a test drive (even the company’s sales department will offer one themselves). A test drive will help you understand the critical factors based on which you will decide to buy a car. You can check the comfort level, handling, braking system, etc., and provide your feedback for further improvements in the vehicle.

Software testing is similar to a test drive. The only differences are that in place of a car, the product tested is software, and instead of users, the testing team of a company does this job. The testers run a performance check, look for the areas that can improve, and fix the bugs ruining its functioning. The ultimate objective is to identify bugs and loopholes hindering the users’ requirements and expectations. For this purpose, several methods and tools (both manual and automated) are available in the market. This article will discuss the two most prevalent ones.

Unit Testing and Integration Testing

Consider the same example of a car test drive mentioned above. There are two ways to test the car and make up your mind to purchase it. The first is to evaluate each car segment separately, such as its wheels, seats, brakes, etc. Another method is to check the car as a single entity, like how its pick-up is or how comfortable it is while driving.

The same concepts apply to software testing as well. A software product combines different modules that different development teams might have created. When developers themselves test a single module (or a unit of code), it is known as unit testing. However, if those different modules are combined and tested by the testers, the process is known as integration testing. Let’s discuss these two in detail.

Unit Testing

Unit testing is a process of evaluating individual components of codes; developers usually carry these out. Unit tests, also known as test cases, consist of different segments that work in unison to perform a specific role.

Unit Test Vs. Integration Test

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Unit testing has nothing to do with the user interface or the user-end functions of the software application. That is because there is no interaction of the unit tests with the underlying APIs.

One of the unique things about a unit test is that it does not involve the end-user as the target audience, which is common in other forms of testing. Unit testing does not focus on usability and other non-functional aspects of the software. However, it is still essential to ensure and authenticate that the user requirements are appropriately met. Moreover, it minimizes the cost of bug fixes and the risk of software failures as the developers identify the errors in the early phases of the software development lifecycle (SDLC). 

How Does a Unit Test Work?

Performing unit testing is not a tough grind. All you need to do is to add test cases referring to specific errors that are pretty common and easily identified during production usage. The qualitative aspect of the unit testing depends on how critically you examine and implement the test cases. Mostly, unit testing is executed in the critical parts of software, such as login, registration, payment, etc.

The ultimate goal of a unit test is to check the structure, stability, and performance of the code written by the developer. The better the code quality, the greater the results are shown by the software.

Integration Testing

Regarding integration testing, it is a process of combining different units (or modules) of programs and testing them as a group. These modules are logically integrated and examined with the help of test drivers and test stubs.

The principal focus of integration testing is on data communication and networking. That’s why it is also regarded as thread testing or string testing. The testers performing integration testing consider by default that a software comprises several modules coded by different developers. It is like a motorbike; the designer constructs the basic structure of the bike, the mechanics build the parts, the assembler assembles them, and the painter is responsible for its embellishment. However, the quality analyst examines the entire motorbike as a single entity by checking all the checkpoints related to quality assurance.

How Does Integration Testing Work?

One can perform integration testing in two ways:

  • Top-down method
  • Bottom-up method

The top-down method deals with testing the macro components first. It looks at the bigger picture and focuses on the general parts at the beginning and specific constituents later. However, the bottom-down method follows an entirely different approach. It primarily focuses on software’s particular features and micro details before moving to its general attributes.

Unit Test Vs. Integration Test: How They Are Unlike in Kind?

You should know that both unit and integration testing come under functional testing, requiring proficient testers to analyze the code and identify errors. Even both of these methods use somewhat similar tools to test software. However, they are still pretty different in how they are tested and what is tested.

As mentioned above, a unit test involves testing a single segment of a code, while an integration test deals with the complete testing of all the code modules. A unit test ensures that an individual code component does what it is supposed to do. On the other hand, integration testing makes sure that all the code components are interacting and functioning perfectly with each other. Here is the list of key differences between these two types of functional testing:

Unit Testing Integration Testing
Unit testing examines the behavior of the single component of a software. Integration testing examines the combined behavior of all the modules integrated together to form the software.
Unit testing has a narrow scope as it only covers and checks a unit segment under test. Integration testing has a broad scope as it covers the entire software application under test.
There are no dependencies on the code outside the individual segment tested in the case of unit testing. There is a massive dependency on other outer systems like assigned hardware, databases, etc., as the whole software is under test in the case of integration testing.
It is the initial testing that needs to be done by the developer. It takes place in the early stages of the SDLC. Integration testing is generally carried out after unit testing and prior to system testing by a qualified team of testers.
It begins with the module specification. It begins with the interface specification.
Identifying errors in a unit test is easy as you only need to examine a single code segment. Identifying errors in an integration test are challenging as the entire software application comprising all the modules is under examination.
The cost of maintenance in unit testing is affordable. The cost of maintenance in integration testing is expensive.
Unit testing is a white-box testing approach. Integration testing can be both white box and black-box testing.

Wrapping Up

No user wants a software application that is not up to the mark. Similarly, no developer wants to develop or sell software with errors and loopholes. That’s why testing plays a crucial role in the SDLC.

Integration testing ensures that everything is aligned and properly working in the overall system after integrating all the modules. However, when you still face issues while (or after) performing integration testing, you need to go for the unit testing to get specific details of the bugs and fix them. Therefore, the bottom line is that although these two methods are unlike each other, you need both to successfully test a software application and get one that accomplishes milestones. 

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