Digital Skynet - 4 Levels Of Software Testing | Digital Skynet

4 levels of software testing

April 15, 2019
#SoftwareDevelopment #QA

It’s not groundbreaking to claim that software testing is crucial to its development. But what do you know about the process of quality assurance?

It’s logical to assume that it happens after the code is written to see if it work properly. But is it that simple? Or is it simple at all? You can write a book, for example, send it to an editor, and after some time get the finished result. Software QA is more involved than that. When it comes to software it a complex process that may take longer than the initial coding itself with the project going back and forth between testers and developers on its way to completion. Let’s dive in and look at that important task in detail.


What Is Software Testing?


According to the ANSI/IEEE 1059 standard, software testing is a process of analyzing a software item to detect the differences between existing and required conditions (i.e., defects) and to evaluate its features.

Software testing is not just a simple search for bugs though. This is a complex process aimed at determining the quality of a software product in line with expectations and customer requirements. Testing in software development is extremely because bugs and errors could potentially be expensive or even dangerous. For example, in April 2015, the Bloomberg terminal in London crashed due to a software glitch and affected more than 300,000 traders in the financial markets. It forced the government to postpone a 3 billion pound debt sale.

On a smaller scale, think of the potential users who choose another app to yours because of a random review that mentioned a bug. Whatever the case may be encountering bugs is never pleasant. They stand in the way of you doing what you want, they take up your time to go around and they are quite simply annoying.

So how do you minimize the risk of facing them? Software testing process has 4 levels and each level has a specific purpose:

  • Unit testing
  • Integration testing
  • System testing
  • Acceptance testing

Let’s take a closer look at each one of them to see how they make the software product better.


1. Unit Testing


Unit testing is a level of the software testing process where individual units of software are tested. A unit (also sometimes called component) is the smallest functional part of a program or application. The unit cannot function on its own and requires to be in combination with other units. But that doesn’t mean they can’t be tested separately. In fact, they are the smallest possible testable elements of code. So, why do you need to test them in such a way? They allow you to quickly check whether the code change has led to errors in the already tested parts of the program. It also facilitates the detection and elimination of such errors.
Developers write tests for each non-trivial function or method. However, testing automation tools become more and more refined. They save a lot of time when you need to make a lot of small changes and can provide feedback almost instantly. However, even though a unit is small by its nature, it still can result in major bugs, so completely eliminating human oversight is never advised.

2. Integration Testing


Integration testing is the next level after unit testing. This is a stage of the software testing process where a group of interacting modules is tested together. The purpose of integration testing is to ensure that the modules function successfully in conjunction with each other. This testing level is designed to find interface defects between the modules and functions.

There are several approaches to integration testing:

  • Bottom-up Integration Testing:

Testing takes place from the bottom up. The lowest level modules are tested first, moving up to the higher-level modules. It finally culminates in integrating the high-level modules to a low level to ensure the system is working as intended. Drivers are used as a temporary module for integration testing.

  • Top-down Integration Testing:

Top-down integration testing is a technique used to simulate the behavior of the lower-level modules that are not yet integrated. Stubs are the modules that act as a temporary replacement for a called module and give the same output as that of the actual product.


3. System Testing


System testing is a level of the software testing process where the application is tested as a whole. At this stage, the entirety of the code is tested in an environment similar to the one where the finished program will be deployed. The goal at this level is to evaluate whether the system has complied with all of the requirements specified at the start of the development.

As you can see, we are moving up in complexity as we go through the levels of software testing. Gradually increasing the number of code components in a test, eventually reaching the entire system, helps to detect the bugs and defects early on. Going straight to the system testing is a recipe for disaster since you often have no idea which one of many units was the cause for the error.

There are two approaches to system testing:

  • Requirements based - for each one of the requirements, test cases are written to verify that this requirement is met.
  • Use case based - it takes as a foundation the scenarios and patterns of how end-users will interact with the finished product. For each specific use case, one or more scenarios can be defined. Test cases are written for each of these scripts to be tested.

4. Acceptance Testing


Acceptance testing is a formal testing process that checks the compliance of the system with the requirements and is conducted with the aim of:

  • determining whether or not the system meets the acceptance criteria;
  • deciding whether or not the needs of the end-user, the client and/or the product owner are satisfied.

During this stage, the client will test the system to find out whether the application meets the needs of their business. It can often be performed by external unbiased teams in order to ensure that subjective judgment doesn’t get in the way of the actual functionality of the app. If the system passes this test, then it is ready for release.


Where Our Software Testing Process Begins


The work of Digital Skynet is in line with Agile methodologies. We conduct tests throughout all of the development stages. The software testing process in our company begins at the stage of customer requirements analysis. Right out of the gate we must determine whether or not the initial customer requirements are at all realistic. This is the first step in the Software Testing Life Cycle (STLC). You can read about it in more detail in this article.

So, why do our QA-engineers start their work at the stage of requirements analysis? In the early stages, it is easier to find bugs and fix them before they snowball into bigger errors. When requirements are determined and clear, the development can begin. Each one of the developers checks their part of the code. Then, our QA-team checks the code again. We believe that frequent code-reviewing helps to avoid bugs and improve the quality of the code.


Wrapping Things Up


Rigorous software testing at all stages of development makes the end-product more stable, subsequently leading to better user experience and more benefits for our clients. The four levels of testing help us ensure that you are satisfied with our work.

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