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 to it needs to be tested first.
Let’s understand Progressive Testing/Increment Testing in more elaborately way by going little bit deep into it. This Increment Testing is considered as sub testing technique which comes under Integration Testing. Actually this testing acts as an approach/strategy to perform integration testing on software product rather as direct testing activities.
After completion of Unit Testing over each individual components of the software, then the Integration Testing is performed to ensure proper interface and interaction between components of system. Incremental testing or Progressive testing is treated as 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 as Incremental Testing.
Working of Incremental Testing :
- Unit testing is performed on each unit of system and after passing unit test it is kept in isolation.
- Each units are tested independently with required parameters to compensate for integration testing with other components.
- Units are assembled and integration testing is performed incrementally.
Incremental Testing Approaches :
- Bottom up approach –
In Bottom-up approach all components are combined one by one from bottom level to top level until all components are integrated.
Top down approach–
In Top down approach all components are combined one by one from top level to bottom level until all components are integrated. Stubs are used to replace need for essential components.
- Functional approach –
In Functional approach testing is carried out horizontally means integration is done based on functionality. That’s why it is also named as Functional Increment.
- Hybrid approach –
In Hybrid approach both Top down approach with Bottom up approach is followed. In this we exploit advantages of both Top down approach and Bottom up approach.
Key points of Incremental Testing :
- Increment testing involves execution of integration tests over each of components.
- To fulfill requirements of other necessary units or components drivers and stubs are used as substitute.
- But stubs may increase complexity of software.
- It is easy to detect defects/faults in small subsystem as compared to large subsystem.
- It is time consuming process, implantation requires lot time.
- Incremental approach gives advantage in early detection of any defects than that of non-incremental approach.
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