Progressive Testing in Software Testing

Progressive Testing is also known as Incremental Testing. In Software Testing Incremental Testing refers to test modules one after another. When in an application parent-child modules are tested related modules need to be tested first.

Let’s understand Progressive Testing/Increment Testing more elaborately by going a little bit deeper into it. This Increment Testing is considered a sub-testing technique that comes under Integration Testing. This testing acts as an approach/strategy to perform integration testing on software products rather than direct testing activities.

After completion of Unit Testing over each component of the software, then  Integration Testing is performed to ensure proper interface and interaction between components of the system. Incremental testing or Progressive testing is treated as a partial phase of Integration testing. First, it performs Integration testing on standalone components thereafter it goes on integrating components and performs integration testing over them accordingly. As the components are integrated in an incremental manner that’s why also it is termed Incremental Testing.

Working of Incremental Testing

• Unit Testing: To make sure that every unit performs as planned and satisfies its requirements, it is independently tested, usually with the use of automated testing frameworks. Units are considered to be operating correctly in isolation if they have completed their unit tests.
• Parameterized Testing: To cover a range of situations and edge cases, units are evaluated with different input parameters during the testing process. Given that many inputs may cause the unit to behave differently, this helps to guarantee that testing is robust and complete.
• Isolation: The units are maintained in isolation, which means they haven’t been integrated with other system components until they pass unit tests. As a result, testing individual units may be done with greater focus and control because interactions with other components don’t complicate matters.
• Testing for Incremental Integration: Following testing and verification, individual units are progressively included into larger system components or subsystems. Testing the relationships between units, integrating them incrementally, and finding any compatibility or integration problems as they appear are all part of incremental integration testing.

Progressive Testing Approaches

1. Bottom-up approach – In the Bottom-up approach all components are combined one by one from bottom level to top level until all components are integrated.
2. Top-down approach – In Top top-down approach all components are combined one by one from the top level to the bottom level until all components are integrated. Stubs are used to replace the need for essential components.
3. Functional approach – In the Functional approach testing is carried out horizontally means integration is done based on functionality. That’s why it is also named Functional Increment.
4. Hybrid approach – In the Hybrid approach both the top-down approach and with Bottom approach are followed. In this, we exploit the advantages of both the Top-down approach and the Bottom-up approach.

Key Points of Progressive Testing

• Increment testing involves the execution of integration tests over each of the components.
• To fulfill requirements of other necessary units or components drivers and stubs are used as substitutes.
• But stubs may increase the complexity of software.
• It is easy to detect defects/faults in small subsystems as compared to large subsystems.
• It is time time-consuming process, implantation requires a lot of time.
• The incremental approach gives an advantage in the early detection of any defects over that of the non-incremental approach.

Best Practices for Implementing Progressive Testing

• Prioritize Test Cases: Test case prioritization should be done by taking into account factors like risk, criticality, and business effect. It reduces the possibility of problems that could affect the software’s overall quality.
• Feedback Loop: To promote cooperation and communication between the development and testing teams, set up a feedback loop. Motivate developers to take part in testing and to quickly report on test findings.
• Start Early: In the software development lifecycle, start testing as soon as feasible. This lowers the possibility of costly repairs later in the process by enabling the early detection and correction of flaws.
• Automate Testing: Try to automate as much testing as you can, particularly repetitive activities and regression tests. Improved test coverage, early defect discovery, and faster test execution are all made possible by automated testing.
• Track and Measure: Keep a close eye on the status of testing, test coverage, and defect metrics. Utilize this information to identify areas in need of development and to help you decide which tests should come first.