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Software Testing 101: Types of Testing in Software Engineering

Every engineer knows the importance of using diverse types of testing in software development. Here, we'll mention some of the most important testing strategies you should know.

Every project that involves software engineering is unique, and thus requires a unique testing process. If your main goal is to deliver quality software products on time within a defined budget, your Quality Assurance (QA) teams must combine various testing types. Expert QA engineers should strive to learn about the product in depth and complete several rounds of testing to eliminate potential bugs and ensure premium quality.

Any development project today includes a combination of testing strategies. In every phase of development, QA and developers collaborate to ensure that code is working as expected to guarantee a high calibre software solution. 

At Softjourn, we know how important testing is. That's why this article will take you through the distinct types of testing in software engineering. We'll share some of our insights on the software testing process and explain some of the best test strategies for your software development project.

The Importance of Quality Assurance, Control, and Testing

The Importance of Quality Assurance, Control, and Testing

We can say that QA focuses on providing continuous and consistent improvement of software products so that Quality Control (QC) can monitor whether the product behaves as expected. QA focuses on preventing any omissions that could affect the software’s functionality.

A graphic illustrates how Quality Assurance, Quality Control, and Testing work in tandem to resolve errors in software development.

QA, QC, and testing all go hand-in-hand to create a superior software product.

QC is a process that verifies software quality and whether all requirements were met. It focuses on the whole product and not on specific elements, as it aims to assess a software product’s functionality.

Once a software product passes through both the QA and QC phases, it's time for testing. Testing is a hands-on approach that aims to thoroughly examine the source code and solve errors . Applying different types of testing in software development aids in the detection of errors. This allows the development team to remove those errors quickly.

Types of Testing Strategies in Software Engineering

Types of Testing Strategies in Software Engineering

What is Software Testing?

Software testing is a process used to evaluate the functionality of a software application. It is performed with the intent of producing a quality product that meets specified requirements and is defect free.

One of the best ways to test software is by simulating a user's actions on an app interface. Structural features of any software are hard to manage as it relies mostly on the expertise of the developers who created the code. On the other hand, software functionality can only be verified through QA, QC, and testing.

Organizing software testing is not as simple as it might sound. To achieve success, use three distinct phases: planning, execution, and reporting.

In the planning phase, all team members meticulously lay out all relevant testing activities. This phase's main objective is to educate the team on the software's purpose and all of its functions. Also, the team needs to evaluate the possible risks as well as the outcomes they wish to achieve.

Test Strategies

A good test strategy is a key factor that often determines a product's quality. Testers and test team leaders decide on the approach according to product requirements and potential problems that a certain software type might have.

The team also collaborates to create a test strategy document to align all activities, create viable deadlines, and coordinate with other developers. With documentation, the final product will be on point, and the process to make it will help everyone stay on track. There are several distinctive test strategies a team can decide to use:

  • Analytical
  • Model-based
  • Methodical
  • Process
  • Dynamic
  • Consultative or Directive
  • Regression-averse

While every strategy has its pros and cons, some lean towards prevention while other methods are reactive. For example, analytical test strategies lean towards prevention as they are involved in identifying early-stage defects. That way, your QA team can solve simple problems in the first stages of product development.

Reactive strategies are also important as they pick up problems that slip by in the beginning. As software structure grows more complex, locating the origin of a problem becomes harder to figure out. Reactive tools might help you in that regard.

Choosing the Right Strategy

Because there are many areas to consider, it is not always easy to decide on the best testing approach. A QA team must consider the risks involved in the process, as it is not the same to develop an update for a well-established app versus build a new product.

It is also important to weigh all of the QA team's skills and whether they're able to create a unique approach. If not, make sure to choose a strategy they understand and know how to execute.

Different Types of Software Testing

Distinct Types of Software Testing

Mistakes are a common thing for every software engineer. However, some errors might come with a high cost. And with specific types of software testing, they could be eradicated. Since every software product should meet particular requirements, all its functions and features should deliver.

Before releasing any software, every development team has to check its performance and quality. In general terms, we can divide all types of testing in software engineering into three groups:

  • Testing by Aims
  • Testing by Execution Method
  • Testing-by-Testing Level

Types of Testing by Aims

Types of Testing by Aims

Functional Testing

Every development project is unique due to its prioritization and testing activities. If you want to deliver quality software in a timely manner, QA teams ought to combine various approaches and testing types.

Every QA engineer knows how important functional testing is, regardless of the type of software they're creating. In functional testing, the QA team runs the system against functional requirements and analyzes the output. If the outcome is different compared to expected values, that means that there's more work to be done.

Functional testing typically uses the following set of actions:

  1. Outlining the functions that software has to perform
  2. Data input
  3. Definition of the expected outputs
  4. Execution of the test
  5. Comparison of expected and received outputs

A functional test focuses on design specifications and the functionality of the software solution. It assesses its practicality, features, performance, user-friendliness, and spots defects that might change its quality.

Confirmation Testing

When a QA team spots a bug and reports it, developers need to fix it so the software will get an updated version. Then, it's time to re-execute the test case that failed. That way, the QA team can confirm that everything works well. Confirmation testing should be performed on all testing levels since it is one of the best ways to validate software functionality. It is important to ensure such testing is executed in exactly the same way as it was the first time, using the same inputs, data, and environment to not introduce any new variables. 

Regression Testing

Another useful functional testing type is regression testing. Once new changes have been implemented, the testing team uses a regression test to check what effect the change had on the software. A QA specialist can select some test cases and partially or fully re-execute the core software functionality units. Test cases that show any defects deserve the most attention.

Smoke Testing

QA teams conduct smoke testing between development and full-scale testing. Some call it build verification testing since the development team sends the project build to QA to check whether the code is crash-proof. One way to do this is to thoroughly analyze the basic functions to discover potential problems. Smoke testing results are used to decide if a build is stable enough to continue with other testing phases and whether to announce a production release.

Sanity Testing

QA performs sanity testing only when they don’t have enough time to run all test cases. When you need to check all crucial elements of your code and deliver it fast, sanity testing is shallow but can give you a basic overview of the product's functionality. Sanity testing should not be used regularly. It is useful in scenarios where only minor changes are done or if something needs to be delivered urgently.

However, if your software fails a sanity test, it will be rejected by the testing team to save time as well as money. When the product passes the sanity test, the QA team can accept and continue other testing phases.

Exploratory Testing

One of the most commonly used testing models in Agile methodology is exploratory testing. It allows QA engineers to create individual tests and simultaneously test design and execution. When it is time to discover what software can do and if it can perform functions without bugs, unscripted tests are among the best solutions.

Since scripted testing has many limitations, exploratory tests are all about improving the test design and offering innovative solutions for software problems.

Nonfunctional Testing

Different software testing methodologies are necessary to ensure a software product’s quality. That's why both functional and nonfunctional tests are essential for product development. Proper testing will guide your team toward the best solution, and keep them in compliance with product documentation and requirements.

When QA engineers start nonfunctional testing, they're usually looking for validation of the nonfunctional aspects of the software, including:

  • Performance
  • Usability
  • Security
  • Compatibility
  • Compliance
  • Localization

Types of Testing by Execution

Performance Group (Performance Testing, Stress Testing, Stability Testing)

All types of performance testing aim to verify the responsiveness as well as the stability of the system under a heavy load. Depending on the number of processes happening, the QA team can run a number of performance tests.

Load testing is used to check how software behaves under an increasing workload. Stress testing focuses on finding the limits of the system as it analyses how it manages an excessive workload. Spike and endurance tests try to measure the system's response to sudden changes in workload amounts and its reactions to continuous work over a certain period.

UI/UX Testing

When a product gets its design, a UI/UX expert should check the efficiency and user-friendliness of the software. Since this is one of the nonfunctional types of testing, its focus is on functionality from an average user's perspective. This type of testing is quite different from others as it analyses interaction between a software product and its users.

This type of testing is a key part of the business analysis process, and it is often conducted right before a product launch. If there's any logical mistake or if the design doesn't deliver, this test will reveal it and provide a chance to fix it.

Usability Testing

The goals of any usability test are to identify any issues, uncover opportunities for improvement, and learn more about user behavior. That's why users are a key component of the process. They're given the app while developers assess how it performs. Users also need to give their feedback on the interface, design, features, and ease of use.

Usability testing has two basic types: qualitative and quantitative tests. While the quantitative usability test focuses on getting insights on how people use the app, the quantitative approach concentrates on metrics that describe the user experience.

Security Testing

Security testing is one of the types of testing in software engineering that inspects software security features. If the app is prone to attacks, hacks, or data leakage, a QA team can alert developers to secure it better.

The basic security concepts that your app has to include are confidentiality, authentication, authorization, non-repudiation, and integrity.

Compatibility Testing

Another useful nonfunctional test conducted by the testing team is compatibility testing. Usually, the best time to do compatibility testing is during full-scale testing as it ensures that the app will work on diverse types of devices.

When it comes to apps, it's instrumental for them to work on any operating system and all browsers. A QA specialist should always run several compatibility tests on different operating systems and all of their versions. This way, a team can validate user engagement and retention to ensure that every user feels good about using the app on their tablet, computer, or phone.

Localization Testing

The process of adapting a product to a different language or region is known as localization. Localization testing is customizing several important aspects of your software to work well in other parts of the world.

Here are key areas that localization testing checks:

  • Time and date formats
  • Keyboard layout
  • Currency
  • Color schemes, symbols, and icons

The main idea of localization is to configure the product to become more appealing to its target audience. Your team can also internationalize the product's design to make it understandable to various people from diverse cultures.

Balancing Functional Testing and Nonfunctional Testing

While functional testing types check whether all functions and features are operating properly, nonfunctional testing checks other aspects of the software like reliability, design, security, and performance.

Once software passes all functional tests, the testing scope could be extended with relevant nonfunctional tests. Which nonfunctional tests are performed should be determined by the QA team, taking into account the application type, its architecture, regulations, and all the devices used to run it.

When you start with testing activities, one of the best ways to start is functional testing. Once you have your software up and running, you can continue with nonfunctional testing. This type of testing in software engineering is only relevant for certain application types, specific architectural complexity, and various regulations.

Should you want to supervise the testing scope, your test teams can decide to use risk-based testing, especially if they already have all potential problems or malfunctions in mind.

Types of Testing by Execution Method

Manual Testing

Manual tests are useful for validating the functionality and usability of a product without using any tools for automation. This type of software engineering testing can determine whether your software follows requirements and specifications. Every test scenario comes with detailed test cases that assess the software's execution and test whether it delivers. It is recommended that a new application must be manually tested before implementing automated testing methods. 

A pie chart depicts different manual testing concepts.

Any type of software testing can be executed both manually and through automation.

Automated Testing

Automated testing is an approach when automated testing software is used to execute test cases.

Subsequent development cycles will need the same test suite performed, often repeatedly. Test automation gives QA testers the ability to record a test suite and replay it as required. This reduces the amount of human intervention needed. While automation can improve the ROI of testing, it is not intended to eliminate manual testing entirely. Automated testing is simply meant to reduce the number of test cases needed to be done manually.

Automated testing can perform checks at the unit level, API level, and UI level.

On the unit level, all software components should be tested individually. On the API level, the development team has to check the integration of several software components. Lastly, the test team will employ automation tools to simulate users' actions to see how the software will respond on the UI level.

Automated Testing vs. Manual Testing

Automated Testing vs. Manual Testing

Every time you encounter software with a lot of test sessions and just a few iterations, it might be a strong candidate for automated testing. Also, automated testing is a better solution if you're working on various user interface scenarios. When you're working with complex functions, automated testing might take up a lot of your time and project resources.

On the other hand, manual testing is more applicable in situations where specific responses are needed. For example, if changes were made to a function and only that function needs to be validated; or if those specific changes need to be validated against the whole of the system. 

Depending on what you need to validate in your software, both testing types could prove themselves useful.

Types of Testing-by-Testing Level

Types of Testing-by-Testing Level

Every software, from basic to a multilayer solution, is complex as it is made from a number of functional components. That's why it is so important to test every component or integration to get the best results. Diverse types of testing in the software department cover four elements of software:

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

Every team that works according to Agile software development uses this approach iteratively. All of these levels can be applied everywhere, from the smallest units to the complete product. Every unit has to be verified individually and within the rest of the system. If the software shows satisfactory results on all of the stages, the last one will be an acceptance test that indicates if the product is ready for the market.

Unit Testing (Code Level)

Units are the smallest functional parts of any software system. That's why this type of software testing checks every single unit to make sure they meet all requirements. These tests have to be performed by engineers in the earliest development stages, as they can show any problems or malfunctions while the code is still in the making.

Integration Level Testing

Among the diverse types of testing in software development, integration testing is important as they are verifying the combined functionality of the individual units and their group interactions.

There are two approaches to integration testing: from the bottom-up and top-down. The bottom-up approach starts with lower-level unit testing and later moves up to higher-level modules. The top-down method takes a reverse approach since it checks all the complex combinations first, and later focuses on smaller code units.

System Testing

Once the software functions as a whole, system testing is necessary to verify its functions and quality. System testing must be performed by a skilled testing team who use it in an environment that resembles real situations. Using various methods of testing is pivotal so that potential faults within a software product can be revealed with enough time for the development team to address them before the product is delivered to clients. 

Acceptance Testing

The last stage of the testing process is acceptance testing. This ultimate step allows the development team to check whether the software complies with all user requirements. What's more, the team can assess whether the software is ready to be shipped to the client at this stage. In this type of testing, the testing team is checking the overall system, not its components. It is of immense importance to examine the overall system's quality, content, UI, and see whether there are any performance issues.

In some cases, acceptance testing might have alpha and beta phases where developers give the software to actual users to see how it will behave.

Conclusion

Testing methodologies sometimes sound easy to create and execute, but most are quite complex. QA teams must demonstrate not just technical knowledge and experience, but also business and industry insight that will help evolve the end product. Proper testing is instrumental in developing a new product.

Recent studies show how small problems can quickly grow into big business problems that are very hard to solve in the late development stages. That's why some developer teams insist on doing developer-based testing rather than leaving it solely to QA. There's no “correct” solution when it comes to testing strategies. Now that you’ve read our article about different types of testing you can decide what will best serve your customers.