Software testing is essential to maintaining your organization’s systems. Without routine testing, bugs, functionality issues, and security vulnerabilities are much more likely to appear. These issues can affect everything from the customer experience and your employees’ productivity to the reputation of your business (security vulnerabilities can lead to significant data breaches that won’t reflect well on your company).
Testing can help identify problems that need to be addressed right away as well as potential issues that can cause problems in the future. Unfortunately, there is no single test that you can run that will cover all your bases. To ensure that all of your systems are functioning properly without any kind of issues, you will need to run a variety of different software tests. Different tests achieve different goals, but they will all contribute to maintaining and improving your systems across your organization.
Principles of Software Testing
The main goal of software testing is to ensure that all customer requirements are met. Whether the application is customer-facing or for internal use, the whole point of testing is customer experience. Because constant exhaustive testing is not always possible, determine your system’s optimal amount of testing based on the software’s risk assessment. Testing is something that needs to be planned ahead of time.
The Pareto rule states that 80 percent of all software errors come from 20 percent of its components. Start testing small parts of the software, then expand your testing to larger parts.
Software testing is classified into three different categories: testing levels, testing methods, and testing types. Testing levels are the different types of testing that a software goes through at different stages of development, and include the following:
- Unit Testing – Unit testing involves testing individual units of a software. A programmer will run a unit test by testing an individual unit or a group of interrelated units by using a sample input and then observing the corresponding outputs to identify defects.
- Integration Testing – Integration testing observes how units work together. The goal is to take the units that were previously tested and to test the output against a group of combined components.
- System Testing – System testing tries the software on different operating systems. It is done using the black box testing method since the tester only has to focus on the required input and output without having to focus on the internal structure. System testing involves several other types of testing, including security, recovery, stress, and performance testing.
- Acceptance Testing – Acceptance testing is performed once the software has been completed to determine if its quality is acceptable for delivery and that it meets all business requirements.
These are the main testing levels. There are many different types of software tests that can be executed at every testing level. The way that these tests are executed is referred to as the methods of software testing.
Methods of Software Testing
There are several types of software tests along with countless testing applications that you can run. The methods of testing refer to the ways in which the tests are conducted. The following are five of the main methods of software testing:
- Black Box Testing – Black box testing is a method in which the individual testing the software does not need coding expertise, nor do they need to have knowledge of the software’s internal structure. Instead, black box testing allows the user to rely on the testing software with various inputs. They can then validate the results against the expected output.
- White Box Testing – White box testing requires knowledge of the software’s internal working. It’s typically used by software developers in unit testing to perform code and test statements, data flow path, decisions, and branches within the software being tested. The white box testing method is sometimes referred to by a number of other names, including glass box testing, transparent box testing, and clear box testing.
- Gray Box Testing – Gray box testing combines black box and white box testing methodologies by testing a piece of the software against its specifications in addition to using knowledge about the software’s internal structure. Both software development and testing teams can use this testing method.
- Agile Testing – Agile testing is a method in which the software is tested as it is coded. This allows for iterative coding and testing and ensures that major problems aren’t found with the code late in the development process (which can otherwise result in significant delays). Agile testing is an essential step in agile software development.
- Adhoc Testing or Exploratory Testing – Adhoc testing, also known as exploratory testing is a testing method designed to discover defects missed by existing test cases. Adhoc testing can be executed without reference to existing test design documents or test cases and is a more informal and unstructured method that can be executed by any stakeholder. However, a comprehensive understanding of the domain and the workflows of the software are required of whoever is performing the test in order to find defects.
Unit Level Testing or Component Level Testing
The common software tests used to test the individual components of an application are many. Just to name a few, there is:
- Active Testing – A test where test data is introduced and the execution results are analyzed. Active testing is generally performed by the testing team.
- Assertion Testing – Assertion testing is done by testing teams to ensure that the conditions confirm the product’s requirements.
- API Testing – API testing targets the code level of a software. However, it is usually run by the quality assurance team and not the developer.
- Basis Path Testing – Basis path testing is used by testing teams to define test cases.
- Branch Testing – Branch testing is performed by the developer using the white box testing method to test every branch in the software’s source code at least once.
- Mutation Testing – Mutation testing refers to the modification of a software’s source code in minor ways. This allows testing teams to test parts of the code that are rarely accessed during the execution of standard tests.
- Loop Testing – Loop testing is done to test the validity of the software’s loop constructs. It is a white box testing technique meant to help fix loop repetition issues, identify problems with loop initialization, identify performance or capacity bottlenecks, and more.
- Code-Driven Testing – Code-driven testing involves the use of testing frameworks that allow developers to run unit tests. This allows the developer to determine whether parts of the code are acting correctly under different circumstances.
- Boundary Value Testing – Boundary value testing allows quality assurance teams to find existing defects at boundary values (extreme ends of the input values).
- Equivalence Partitioning Testing – Quality assurance teams will often perform equivalence partitioning testing to remove test cases that are deemed redundant within a specific group that generates the same output but not a defect. They do this using a black box testing method to divide the software unit’s input data into partitions of data.
- Configuration Testing – Performance testing engineers use configuration testing to identify the optimal configuration of hardware and software. They will also determine the effect of modifying or adding different resources to the hardware or software, such as memory, CPU, and disk drives.
- Context-Driven Testing – Context-driven testing is a form of agile testing in which new testing opportunities are evaluated if they come up when potential information is revealed.
- Decision Coverage Testing – Decision coverage testing involves testing every condition and decision of the software by setting it on true/false. This type of testing is commonly executed by automation testing teams.
- Dependency Testing – Dependency testing is when the requirements for pre-existing software, configuration, and initial states that an application might have are examined to ensure proper functionality.
- Dynamic Testing (Static Testing, Validation Testing) – Dynamic testing is performed by testing teams to test the dynamic behavior of the software’s code. This typically involves static testing, in which the code is manually checked for errors, and validation testing, in which the software is tested to ensure it satisfies the specified business requirements.
- Formal Verification Testing – The quality assurance team will perform formal verification testing to test the correctness of the intended algorithms underlying a system using formal methods of mathematics.
- Fuzz Testing – The objective of fuzz testing is to identify coding errors and security vulnerabilities in the software. This is done by inputting “fuzz,” which is invalid or random data, into the system. The testing team will then monitor the system for various exceptions, such as if the built-in code fails or the entire system breaks down.
- Modularity-Driven Testing – Modularity-driven testing involves the creation of independent scripts that represent the software’s modules, functions, and sections. These smaller scripts are then used to build larger tests.
- Negative Testing – Negative testing is a testing technique used to check a software’s performance under unexpected conditions. This is done by monitoring how the software performs under negative conditions, such as a hacking attack or the input of a wrong data type.
- Path Testing – Path testing is a white box testing method performed by the development team to find every possible executable path in the software. This is done using the source code and helps the team to identify any faults that might exist within a piece of code.
- Regression Testing – Regression testing is a full or partial selection of previously executed test cases that are performed again to ensure that the software’s existing functionality is working properly. Regression testing is typically done when new code changes are made to ensure that these changes haven’t affected the software’s existing features.
- Statement Testing – Statement testing is a white box testing method used by the development team to ensure that each statement in an application is executed at least once during the testing phase.
- Smoke Testing – Smoke testing is used after the software is built to make sure that the application’s functionalities work properly. Smoke testing is done prior to functional testing or regression testing. This allows the development team to reject software that’s badly broken before the quality assurance team wastes their time testing it.
- Structural Testing – Software developers perform structural testing to make sure that each program statement is capable of correctly performing its intended function. The technique is executed using the white box testing method.
- Upgrade Testing – Upgrade testing is performed by the testing team to make sure that assets created with older versions of the software can be properly used.
- Volume Testing – Also known as “flood testing,” volume testing is done to judge the software’s ability to handle a huge volume of data. By performing volume testing, you can identify load issues, identify bottlenecks, and make sure the system is ready for real-world use.
Integration Level Testing
After testing individual units of a software, units will need to be combined so that they can be tested as a group. This is known as integration level testing. We’ve summarized some of the more common integration level tests:
- Top-Down Testing – Top-down testing, also referred to as thread testing, is typically done at the early stage of the integration testing level. Top-down testing is done by the testing team to test the key functional capabilities of a specific task by beginning at the user interface and then using stubs to test from the top down.
- Bottom-Up Testing – Bottom-up testing involves developing the module at the lowest level first. Other modules that go towards the main program are then integrated as well as tested one at a time.
- Hybrid Integration Testing – Hybrid integration testing combines bottom-up and top-down testing.
- Big Bang Integration Testing – Big bang integration testing is done by the testing team once everything is ready to integrate individual program modules.
- Interface Testing (User Interface Testing, GUI Testing) – Also referred to as user interface testing or GUI testing, interface testing is performed by both testing and development teams to determine whether different systems and components are capable of correctly communicating to each other.
- System Integration Testing – System integration testing is performed by the testing team to evaluate the behavior of all hardware and software systems that have been integrated together into one complete system.
System Level Testing (End-to-End Testing)
These system level tests are run regularly on existing software that has already been completed and integrated:
- Age Testing – Age testing is used to determine how effectively a system can perform in the future.
- All-Pairs or Pairwise Testing – All-pairs testing, also called pairwise testing, is used by the testing team to test all of the potential discrete combinations of input parameters in a system.
- Automated Testing – Automated testing is automatically performed by an automation tool without the need for manual input. Automation tools can be used to automatically enter test data, automatically compare test results, and automatically create test reports. Both condition coverage testing (which tests the execution of each condition by making it true and false) and domain testing (which ensures that the software only accepts valid input) are generally automated.
- Compatibility Testing – Compatibility testing is performed by the testing team to evaluate how well a software runs in a particular environment. There are many types of compatibility tests, such as backward compatibility testing, which determines how newly developed applications behave with previous versions of the test environment. Browser compatibility is commonly run as well to identify whether your application runs properly on different browsers.
- Benchmark Testing – Benchmark testing is run by testing teams to determine how systems perform in a given configuration. A benchmark needs to be quantifiable so that the system can be routinely tested against its own previous results.
- Binary Portability Testing – Binary portability testing is performed by testing teams to determine how portable an application is across platforms and environments.
- Breadth Testing – Breadth testing is done by testing teams to test the full functionality of a software without testing its features in detail.
- Compliance Testing – Compliance testing is generally performed by third parties outside of the organization to determine whether the system was developed in accordance with specific guidelines, procedures, and standards.
- Conformance Testing – Conformance testing is done by testing teams to ensure that the implementation of the system complies with the specifications and conditions on which it is based.
- Conversion Testing – Conversion testing is done by quality assurance teams to test whether a system is able to successfully convert data from an existing software.
- Fault Injection Testing – Quality assurance teams use fault injection testing to evaluate how the system is able to handle exceptions.
- Error-Handling Testing – Error-handling tests are executed by testing teams to evaluate how effectively a software is able to process erroneous transactions.
- Destructive Testing – Destructive testing is done by quality assurance teams to identify a system’s points of failure. This is done by making the software fail intentionally so that the structural performance of the application can be better understood.
- Gorilla Testing – When performing full testing, quality assurance teams will often run gorilla tests as well, which allows them to thoroughly test one particular module to check how robust the application is.
- Globalization Testing – Globalization testing is performed to ensure that the software will function correctly no matter what language it’s in or what territory it’s in. Localization testing is a similar test in which a localized version of the software is tested for the culture or locale it’s meant for.
- Install/Uninstall Testing – Install/uninstall testing is done by the software testing engineer and the configuration manager to evaluate how easy it is for users to either install or uninstall the program.
- Internationalization Testing – Internationalization testing is run by the testing team to ensure that the software remains functional when used in different languages and locales.
- Inter-System Testing – Inter-system testing is conducted by testing teams to evaluate the interconnection between applications.
- Manual Scripted Testing – Manual scripted testing differs from automated testing in that the testing team designs and reviews the test cases before running them.
- Model-Based Testing – Model-based testing involves checking the run time behavior (which can be described as the actions, conditions, input sequences, and more) of a software being tested against the predictions made by a model. Model-based testing is essentially a lightweight and formal way to validate a system.
- Operational Testing – Testing teams use operational testing as a way to evaluate a system or component in its operational environment right before it’s released to production.
- Passive Testing – Passive testing is done by the testing team to evaluate a running system without introducing special test data.
- Parallel Testing – Parallel testing is performed by the testing team when a new application is replacing an older application. The objective is to ensure that the new version has been installed correctly and that it is running properly.
- Penetration Testing – Penetration tests are simulated attacks done to evaluate the security of the system. Most of the time, penetration tests are performed by third parties outside of the organization.
- Performance Testing – Performance testing is done by a performance engineer to evaluate the function of a software. Performance testing typically involves a variety of tests, including load testing, stress testing, spike testing, and endurance testing.
- Qualification Testing – Qualification testing is done by the developer to ensure that a new software meets its specified requirements by testing it against the specifications of an older version of that software.
- Ramp Testing – Ramp tests are run by the testing team or the performance engineer by continuously raising the input signal until the software breaks down.
- Recovery Testing – Testing teams use recovery testing to evaluate how effectively a software is able to recover following a crash, failure, or other severe issues.
- Requirements Testing – Requirement testing is simply done to make sure that all requirements are correct, consistent, complete, and unambiguous. The quality assurance team will then be able to design the proper number of test cases from those requirements.
- Security Testing – Both third party testers and in-house testing teams can perform security testing. This is done to ensure that the system is capable of protecting its data and maintaining its intended functionality. Types of security testing include vulnerability testing, security scanning, penetration testing, risk assessment, security auditing, and more.
- Sanity Testing – Sanity testing helps testing teams determine whether a new software version is performing at an acceptable level so that it’s worth the time and effort to perform major testing efforts.
- Scenario Testing – Scenario testing (also referred to as test condition or test possibility testing) is a type of software testing that involves the creation of test scenarios to study the end-to-end functionality of a software. It allows for an easier way to test more complicated systems.
- Scalability Testing – Scalability testing is done by the performance engineer to determine the software’s ability to scale up, whether it’s due to an increase in data volume, transactions, or user load, to name a few examples.
- Stability Testing – The performance engineer will conduct stability testing to determine how capable an application is of functioning continuously over time using all of its features without failing.
- Storage Testing – The testing team will run storage tests to determine whether the software will store its data files in the correct directories and that it is capable of reserving the proper amount of space to avoid unexpected termination due to a lack of sufficient space.
- Workflow Testing – Workflow tests are run by testing teams to check whether the software’s workflow process reflects the business process accurately.
Acceptance Level Testing
Last, are the acceptance level tests. These ensure that the software being designed is acceptable for production. Tests commonly used to evaluate the acceptability of a system follow:
- Alpha Testing – Alpha testing is conducted to identify any bugs in the software before it’s made available to actual users, whether they are employees or the public. Alpha testing is done prior to the completion of the software but near the end of its development. Both the developers and the quality assurance team typically perform alpha testing. The developer will look for bugs, crashes, missing documents, and missing features, while the quality assurance team will perform additional alpha testing within an environment using both black box testing and white box testing.
- Usability Testing – Usability testing, also referred to as accessibility testing, determines how easy the application will be for the end-user to use. Usability testing is generally conducted by actual end users.
- Beta Testing – Beta testing is the final form of testing done to detect bugs and other defects before the software is launched. It’s executed by releasing the “beta” version of the software to a limited number of end users and receiving feedback on the software’s quality.
- Concurrency Testing – Concurrency testing is performed to determine if there are any defects that occur when multiple users are logged in to the software at the same time and are performing the same action.
Testing is the Foundation of Quality
It can’t be overstated how important the quality of your software is. Poor quality systems can not only affect your employees’ ability to perform their tasks as well as your customer experience, but they can end up affecting the functionality of other systems and applications being used throughout your organization. Software testing is absolutely critical at every stage of a software’s life, including development, integration, and deployment.
Need help structuring your requirements from your testing team? Consult with our experts today.