ISTQB Test Types: Functional Testing

• Test type: Group of test activities with specific objectives aimed at specific characteristics of a component or system, according to the ISTQB Glossary.

Test Type Categories

• Functional testing
• Non-functional testing
• White-box testing
• Change-related testing

Functional Testing

• Evaluates if a component or system satisfies functional requirements.
• Determines what a system does, focusing on specific functionalities.
• Searching for flights or calculating employee pay are examples.
• Functions are typically described in business requirements, functional specifications, use cases, epics, and user stories.
• Black-box testing is related where testing is based on an analysis of the specification of the component or system

Functional Testing Perspectives

• Requirements-based uses a specification as the basis; table of contents is a good starting point, needs prioritization.
• Business-process-based relies on knowledge of business processes, and user scenarios as a basis.

Non-Functional Testing

• Evaluates that a component or system complies with non-functional requirements.
• Tests quality characteristics at all test levels.
• Performance, load, stress, usability, maintainability, reliability, portability, and security testing are included.

White-Box Testing

• Testing is based on an analysis of the internal structure of the component or system.
• Also known as clear-box, code-based, glass-box, or structural testing and primarily looks at the implementation.
• Is most often used as a way of measuring thoroughness
• Is often applied at the component and component integration testing levels.
• At the component integration level, testing is based on the architecture.
• Good tool support is available at the component level, and typically includes coverage measurement.

Confirmation Testing

• Performed after fixing a defect to confirm that a failure caused by that defect does not reoccur.
• A new software version is tested again post-defect fix confirmation
• Also known as re-testing.

Regression Testing

• Executes previously run test cases to verify that software modifications or environment changes have not caused unintended adverse side effects and that the system still meets requirements.
• A regression test suite or pack is common.
• Regression tests are executed whenever the software changes as a result of fixes, new, or changed functionality.

Functional Tests at Each Level

• Component testing: How the component calculates compound interest.
• Component integration testing: How account information from the UI is passed to the business logic.
• System testing: How account holders can apply for a line of credit.
• System integration testing: How the system uses an external microservice to check an account holder’s credit score.
• Acceptance testing: How the banker handles approving or declining a credit application.

Non-Functional Tests at Each Level

• Component testing: Time or number of CPU cycles to perform a complex interest calculation.
• Component integration testing: Checks for buffer overflow (a security flaw) from data passed from the user interface to the business logic.
• System testing: Portability tests on whether the presentation layer works on supported browsers and mobile.
• System integration testing: Reliability tests evaluate robustness if the credit score microservice does not respond.
• Acceptance testing: Usability tests for accessibility of the banker's credit processing interface for people with disabilities.

White-Box Tests at Each Level

• Component testing: Achieves 100% statement and decision coverage for all components performing financial calculations.
• Component integration testing: Coverage of how each screen in the browser interface passes data to the next screen and to the business logic.
• System testing: Coverage of sequences of web pages that can occur during a credit line application.
• System integration testing: Coverage of all possible inquiry types sent to the credit score microservice.
• Acceptance testing: Coverage of all supported financial datafile structures and value ranges for bank-to-bank transfers.

Change-Related Tests at Each Level

• Component testing: Automated regression tests for each component are included in the continuous integration framework and pipeline.
• Component integration testing: Confirmation tests for interface-related defects are activated as the fixes are checked into the code repository.
• System testing: All tests for a given workflow are re-executed if any screen changes.
• System integration testing: As part of continuous deployment of the credit scoring microservice, automated tests of the interactions of the application with the microservice are re-executed.
• Acceptance testing: All previously failed tests are re-executed after defects found in acceptance testing are fixed.

Explore ISTQB test types, focusing on functional testing. Learn how to evaluate if a system satisfies functional requirements. Understand perspectives like requirements-based and business-process-based testing to improve your testing strategies.