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What Is Embedded Software Testing

Anna Khrupa by Anna Khrupa on 06/9/2022

What Is Embedded Software Testing

Embedded Testing is soft- and hardware validation and verification to ensure the entire system is defect-free. That’s the embedded testing definition, but this kind of testing also ensures that the newly-created system meets the end user’s requirements and faultlessly without bugs and glitches. 

In the process of software development, the procedures are often the same: first, the requirements are collected, then the system is designed, and finally, the code is written. The last but not the least important step is testing. 

But what differs embedded testing from software testing? The latter is realized to verify the developed product behavior and is carried out on client servers, the web, or mobile apps. At the same time, embedded testing is performed on the embedded systems and is mostly manual. After ensuring the software is error-free and functions as it was initially expected to, the documentation with all the checked requirements is issued. 

Embedded Systems: What Are They? 

To answer the question “What is embedded system testing?” in detail, we should first define embedded systems. They are the electronic devices in which software and hardware are coupled to accomplish various tasks such as retrieving, processing, storing, and controlling data in variable electronics-based systems. They contain integrated computing mechanisms that perform those specific functions. The users are often not even aware of these inbuilt devices. 

That’s why testing embedded systems differs from traditional software testing in many aspects. So, let’s check how it’s realized. 

How to perform Embedded Software Testing

Since there are minimum 4 reasons for testing, like finding bugs, reducing risks, cutting the development costs down, and performance improvement, variable activities are carried out. However, the mechanism is much like testing software: 

  1. The software is provided with certain input data, 
  2. The piece of it is executed, 
  3. The state of the product is observed. 
  4. The results are checked and compared to the requirements and expected outcomes. 

At the same time, the system must not crash and operate faultlessly. 

In the context of embedded software testing techniques, we can speak about the 2 prevailing ones during the test-driven development: Black Box and White Box Testing. 

Test-driven development is an agile development method where test units are written before the code. However, hardware is often developed simultaneously with software, and often several iterations of the hardware require the consequent changes in software, meaning several rounds of checking. It motivates the developers to plan and understand the specification in detail before the coding, which makes the code more optimized with fewer defects. 

As a result, the problems with integrated testing are minimized. Thus, TDD offers high test coverage and leads to modular design with basic modules of high quality.

In the context of black box testing, a complete verification of all input values results in a sometimes infinite number of test cases. However, they must be measured down and applied along with equivalence partitioning and boundary-value analysis. These techniques are very efficient since they cover each partition of equivalent data in which the input values are divided at least once. 

The White Box testing technique, also known as Clear Box or Glass Box testing, presupposes the structural coding part as well as infrastructure checking. Its primary focus is on strengthening security and improving design and usability. The tester chooses the inputs to execute the certain paths’ flow through the code, and also determines the proper outputs. 

The Most Common Types of Embedded Software Testing

According to system type and general usage in the software industry, we consider five embedded software testing types or levels. They are the following: 

Unit testing 

Every software contains units or components, and unit testing in this case is intended to check whether the code of each unit performs as it’s expected. Software unit testing is realized during the development phase and is led by a developer. It’s usually accomplished in a peer-review model after all the specifications of the software are set, and module test cases are possible to implement. The code of each unit (it may be an object, a module, some function, method, process, or procedure) is then being isolated and its accuracy verified. 

Integration testing 

Integration testing comprises 2 sections in fact — the testing of software and the software/hardware integration. It can also incorporate the interaction between the software and peripheral devices that are built-in. 

The distinguishing feature here is a real environment for testing that is created in parallel with the software to run it. The process cannot be carried out in a simulated condition. The majority of experts consider embedded integration testing a critical task. 

Unit testing of the system 

This step presupposes testing of the modules in a full framework that includes complete software codes, RTOS (real-time operating system), and certain pieces related to a platform like tasking mechanisms, communications, interruptions, and so on. Here, the point of control protocol is rather a message sent/got through the RTOS message queues, then a call to a function or an invocation method. 

Thus, the resources of the system are checked to evaluate its ability to support the execution of the embedded system. 

Integration testing for the system 

This process comprises testing of the entire system, with all its subsystems and components, within a single node. The network communication protocols and RTOS are combined and utilized as the PCOs (Points of Control and Observations). More than that, a virtual tester can also play the role of a node. 

Validation testing for the system and subsystems 

This type of testing is aimed at making sure the entire system that is embedded, and the subsystem, are perfectly and completely implemented. The key purpose is to check whether the external entity meets the product’s functional requirements. It’s vital to remember that the external entity can be either a person, a telecom network device, or both. 

Final Thoughts

The reliance on the hardware environment makes the embedded testing rather a challenging task compared to regular quality assurance. Still, such testing is an excellent way to provide and guarantee security in software solutions and applications for aviation, medicine, railway transport, and much more. That’s why it’s crucial to implement embedded testing to improve software and hardware performance, to reduce risks to both users and companies that utilize embedded systems in their equipment, as well as to bring down the costs of software development and maintenance.

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